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Update: Jump to post #163 for some new revelations....

If your not following Wayne's Prius II thread, we found an interesting spot on the efficiency curve for the Prius II. There seems to be a sweet spot right before the injectors cut out on the way to Warp Stealth. The elusive part is that it looks like it's BELOW the loafing zone for highway driving. Basically it's another "drive-to-a-number" technique, but instead of driving to RPM, you drive to IGN.

Google told me that Ignition Advance (http://www.gill.co.uk/products/digital_ignition/Introduction/9_ign_advance.asp) (IGN) has to do with when in the power stroke to spark the fuel. The ECU will slide this number around as you vary the power demand on the engine. Low numbers are better than high numbers. Anyway, for the Prius, the ECU seems to hang out on an IGN of 14 whenever it's feeling really efficient. What RPM and advance of 14 yields varies widely based on speed, which explains some of the odd numbers that jump out on HW segments. What I've seen is that IGN 14 can happen at 1600 RPM in the city and 1200 RPM for the highway.

Here's a clip from Wayne's Prius Thread about SH mode.

EDIT: Added IGN: -10
Dial in IGN as one of your gauges and watch what happens when hold IGN of 14. Here's the decoder:

IGN: -10 = Manditory S1 ICE-on.
IGN: 5 = Fuel Cut or ICE-off
IGN: 10 = Idle
IGN: 13 = Very hard to hold, happens at about 1100 rpm on the HW
IGN: 14 = SWEET SPOT MPG = 1.5 x MPH and on a flat you can hold it for miles unlike WS. I get slightly better numbers with WS P&G, but man this is the closest I've seen! Something else interesting is that IGN 14 is also what my city driving Pulses seem to hit consistently when at 6 bars. It's a whole lot easier to hold an IGN number than an RPM number, and the RPMS seem to self regulate to the IGN number.
IGN: 15 = Close second to IGN 14, and allows for longer distances.
IGN: 16 = Hardly ever saw it at 6 bars, seemed to always be on the way to 17 or 15
IGN: 17 = FE falls off here, and I recommend avoiding 16 and 17. Possible loafing
IGN: 18 = WS Pulse rate. This is a perfect pulse rate if your gonna WS P&G. Pulse at IGN 18, Glide at IGN 5.
IGN: 19+ = Very fuel thirsty, I recommend avoiding these unless your in a "gotta floor it" moment.



I was using my highway segment as a learning session this weekend, so I only spent about 30 miles on SH mode but the numbers looked good. Came out to about 67 mpg for SH. Basically my driving strategy for SH mode was to hold IGN 14 as long as possible. It seemed that on flats, you can ALMOST maintain speed at this state. Might be a fun mode to try on a distance draft or with a strong tailwind. For the terrain and weather (gobs of rain) I was in, speed would slowly bleed off. So I was using SH as my glide state in a highspeed P&G technique. I'd pulse up to 90 kph (56 mph) at my usual 1600 RPM range. This consistently translated to an IGN value of 18, if you want to go off that (which I would recommend). Once at 90 kph I'd come off the throttle and watch the IGN numbers drop till I was at exactly 14. I'd hold this for MILES until I was down to 80 kph (50 mph), then I'd pulse up again.

Now for some more odd stuff. I'm not sure which OBD-II (http://en.wikipedia.org/wiki/OBD-II_PIDs) request SGII is sending down to get IGN, but it would stand to reason that it was requesting "Timing Advance". Problem is, that the Prius reports that it doesn't support this PID. So I'd expect to get a value of -64, but the values it sends back seem valid. Another point of interest is rounding. OBD-II reports timing advance (IGN?) in half degrees. So the scale may look like {12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 15.5}. So if you notice that sometimes 14 is better than other times, you may be dancing between 13.5 and 14 and not know it. The new XGAUGE feature should fix this.

Another odd thing is that a low IGN is supposed to be BAD. According to the SGII manual (http://www.scangauge.com/support/pdfs/SGIIManual.pdf). It's possible that this is simply the result of being on an Atkinson/Miller (Prius) cycle engine instead of an Otto cycle engine.

This stuff is still in very early beta right now, and there haven't been enough confirmations but Wayne and I have both seen rather consistently that IGN 14 on the highway holds FE over 70 mpg for as long as you can hold it. If you can hold IGN 13, go for it. You should see triple digit FE. I don't think 12 is possible, and going for it will likely transition you to a WS glide (IGN 5).

Anyway, next time your driving around, look at what happens (city and highway) when you hit IGN 14.

Please let us know on this thread if you can confirm good HW segments in SH mode.

11011011

How consistent is that 1200RPM sweet spot on the highway? If you think I can pretty much hit it by watching the tach then I'll give it a shot this week. Or should I concentrate more on MPG=MPHx1.5? I do 40mi/day at 55-60mph so this is exactly the kind of thing that interests me.

Replace RPM on your SGII with IGN. Watch IGN and try to keep it at 14. IGN is on page 8 of the ScanGauge Manual (http://www.scangauge.com/support/pdfs/SGIIManual.pdf). If you just watch RPM or MPG you can't hold it, but if you just watch IGN you should be able to hold it for the majority of your highway miles.

It seems a little underpowered to keep your speed consistent so you will loose 1 mph about every minute or so, depending on terrain.

The key is to change your gauge display to display IGN.

11011011

OK. The thing is I haven't been using the SG at all recently but maybe I'll put it on the dash again to give this a shot.

If your using CanView it has Ignition Timing (AKA Ignition Advance; AKA Timing Advance).

11011011

Hi Tim:

___My baton has been passed to you knowing you have that god awful higher speed highway run. Just setup IGN as one of the 4 displays and camp it at 14 once you have reached a high 6-bar state. I will be very interested in reading your take on it given the amount of highway miles you have to run every day? The higher speed comments will be very interesting reading for many of us here?

___Dan, IGN14 is a “Kick @$$ Ride”, isn’t it :D

___Good Luck

___Wayne

Just setup IGN as one of the 4 displays and camp it at 14 once you have reached a high 6-bar state.

For clarification, where does this additional step come in (quoted from the other thread):

There appears to be two modes to 6 bars of SoC for the highway driver .... When you see the quick flashing yellow arrows from the pack and MGSet mimic, back off just a touch and reapply when it disappears. I mean just a touch so that you are not using the pack.

Hi Jim:

___While driving to IGN14, when you reach 6 bars, there will be an initial area where 70 + is not available. 60 + is but not 70. This has to be a lower 6-bar SoC state but I am guessing on this? After a minute or two more of highway charging, the high 6-bar state arrives and that 70 + SHM is available afterwards.

___Good Luck

___Wayne

For clarification, where does this additional step come in (quoted from the other thread):IGN is as a ScanGauge gauge. Just like LOD. Personally I've selected my 4 gauges as RPM, IGN, MPG, WT.

Once you have that on, try to keep IGN between 13-15 whenever the ICE is on. The one time you can "permit" yourself to take IGN above 16 is when you need to get to speed or recover lost speed (from a long IGN14 glide) on the highway.

11011011

Found another IGN indicator. IGN -10 is when your in the mandatory S1 ICE on mode. The cool part is you can now find out when the EV button is "enabled" after the 60 second S1 run. As soon as IGN goes positive, EV is enabled.

11011011

Found another IGN indicator. IGN -10 is when your in the mandatory S1 ICE on mode. The cool part is you can now find out when the EV button is "enabled" after the 60 second S1 run. As soon as IGN goes positive, EV is enabled.

11011011

You guys rock! I want to take mine out on the highway now, but sadly it would still hurt my current tank even if I could hit the 70+. ;) Re: the above, I have (up until now) done this by "S1-limping" up to 12MPH or so, watching the MFD report instantaneous 11, 13, 15... 17... then the sound of the engine changes, MFD flicks up to 25 or so, and S1 is complete (=EV enabled). 'Grats on finding a hard indicator of this.

While driving to IGN14, when you reach 6 bars, there will be an initial area where 70 + is not available. 60 + is but not 70. This has to be a lower 6-bar SoC state but I am guessing on this? After a minute or two more of highway charging, the high 6-bar state arrives and that 70 + SHM is available afterwards.
This much makes sense, but the implication here is that it arrives spontaneously, whereas your other post suggested it has to be provoked with a slight feathering of the pedal. Can you clarify?

This much makes sense, but the implication here is that it arrives spontaneously, whereas your other post suggested it has to be provoked with a slight feathering of the pedal. Can you clarify?It appears to be self regulating. Just park it at IGN14 and hold it till your going to slow, then pop up to IGN18 for speed, then go back to IGN14. Once you have enough SoC IGN14 will give enough power to give you almost zero deceleration at highway speeds.

Another fun thing is to try IGN14 in the city. This is a 1300-1600 RPM pulse, but it moves around a lot so you gotta chase it. Point is, that I think IGN14 is what we've been chasing forever now. It explains the 1600 RPM efficiency I was seeing earlier and it explains the low RPM efficiency Wayne was seeing.

I consider IGN15 a less aggressive form of IGN14 and IGN13 a more aggressive form of IGN14. Wayne seems to be shooting for IGN13 a lot, I'm usually happy with IGN15 or below.

11011011

I am definitely going to be choosing IGN as one of my SGII gauges from now on. I think I'll go do that right now so I don't forget in the morning.

OK guys. Got another 67 HW segment using SHM. I was doing a pulse and glide with my pulse at IGN18 and my glide at IGN14. I only tried SHM for the last half of the trip. There were heavy rain shows and really torn up roads for the first half, so I just set CC and watched IGN dance. What I saw made since, after I thought about it. When I read up a bit on ignition timing, I think that IGN may be the control that changes RPM. So when you accellerate the followinging happens (I think)

You decide you want to go faster
You increase pressure on the gas pedal
The ECU sees the change in throttle position and increases IGN.
The change in Ignition timing causes more power on the power stroke.
The increased power drives the cam harder (and faster)
The increase in power translates to elevated RPM
I'm sure there are a million other things that happen, not the least of which would be the valve timing which I'm totally blind to. But what I did notice on cruise is that RPM followed IGN. IGN always changed one refresh before RPM or at the same time. As a result it's a lot easier to chase IGN on SGII than it is to chase RPM. Primarily because of the lag inherent in SGII. Tapping the actual TACH would give you near realtime numbers, but I still suspect that IGN changes first (if only by milliseconds). I suspect that IGN swing around a lot will cause a lot of inefficiencies. I've even noticed HSD throwing in some power to keep from (possibly) changing IGN. But since I'm lacking any real education in ICE internals, this is all just supposition.

Just watch IGN to RPM and see what happens for you.

11011011

It seemed that on flats, you can ALMOST maintain speed at this state. Might be a fun mode to try on a distance draft or with a strong tailwind.
11011011

Sounds like a good reason to install some drag reduction mods on your Prius. If you could cut your aero drag load down to where you could maintain speed in IGN14 without benefit of tailwind or drafting, you'd have it made.

Found another IGN indicator. IGN -10 is when your in the mandatory S1 ICE on mode. The cool part is you can now find out when the EV button is "enabled" after the 60 second S1 run. As soon as IGN goes positive, EV is enabled.

11011011

Dan & Wayne, what a great thread, and awesome work on the highway technique. IGN as my "stage 1 done" indicator will replace my other crappy methods:

(1) watch for an iMPG "bump" which varies upon terrain
(2) listen to the ICE
(3) continually attempt to EV switch and get repeated & annoying 3 beeps which prompts the wife to say "what the heck is that, one of your new toys?" ;)
(3) or, old reliable........feather accel, whoops assist, back off, feather accel, whoops assist, back off, feather accel, good to go! :)

As luck would have it, I read this thread over the weekend while on vacation in South Padre Island, TX. Then, while the wife was getting her birthday massage on the beach, I took the kiddo out to the absolute perfect training track...........a two lane, completely flat highway on the island north of all development, free of all people/cars, and paralleling the ocean. Wow. With a solid six bars, I held IGN14 at ~70mpg for a solid distance. It's amazing how instrumentation can help you stick what you probably crossed over many times before.

Dan - I'm coming your way! I'll be at La Salsa for the H3C meeting at noon this Saturday. Looking forward to meeting you, and the other interested Houstonians who show up. The 150 mile trip has a nice downhill elevation on the way, so we'll see what "18&14" will yield me when I pull up.

I'll reply in the H3C thread.

Inspired by the two threads going on about this, I hooked up
the Autoenginuity and went out for a bit of data-collection
this afternoon. First of all, here's my data -- *all* of it:
-> http://techno-fandom.org/~hobbit/cars/sweet/loafing.csv
for anyone's statistical pleasure. I collected spark advance,
RPM, engine torque [which I believe is calculated by the hybrid
ECU from motor torque, but who knows], injector time, and speed.
The file has a label line at the top. I didn't include LOD
because I know that my non-upgraded ECU reports it bizarrely
and I can more or less see it via my vacuum gauge and/or the
torque figure. Then I went back and re-read both threads
in parallel with composing this just to make sure I had the
whole picture. What else to do on a nice sunny Labor Day
afternoon? I already got my labor in, smoothing down and
painting six big cinderblocks for use as tent weights.
.
First of all, you guys have been averaging about 50 mph for
this experiment, right? As xcel points out, that's hard to
do on most of our interstates without a good excuse; today
I managed to poke along mostly at less than 55 but with all
the returning Labor Day beach traffic and big-ass pickups
and boat trailers tailgating everyone in sight and diving
on and off the ramps, that wasn't easy. But my usual "test
track", I-95 on the north-shore section, has 4 and sometimes
5 lanes, so it's a little more reasonable there. Still, at
60-ish people tend to just pass, but down closer to 50 there's
definitely a lot more stink-eye goin' on.
.
So on a relatively fresh tank I tried both techniques for a
while; about 25 miles of 14-advance and then another longish
leg back to my usual minimum-1700-RPM and WS routine. I
oscillated between maybe 48 mph and 60 mph; possibly a little
faster than others' experiments. After the 14-degree time
I was sitting at 66.5 mpg average. After the pulse-n-WS
routine I was seeing 66.4. This wasn't a totally controlled
terrain -- I made a big loop on the local highways, rather
than trying a rigorous A/B two-round-trips test. I figured
if there was going to be any significant difference, I'd
see it simply by eyeballing the 5-minute bars and watching
the average drift. What I really wanted to determine was
the conditions that y'all have been talking about WRT this
s'posedly new technique. Besides the .CSV data, I did note
a couple of other things.
.
The 14-deg mode appears to be able to hold about 47 mph
sustained on the flat. Not useful for interstates by itself,
but obviously allows for a longer glide-down. That's
probably just the balance of output power vs. air resistance.
Spark timing seems to advance farther while engine RPM is
increasing, and retard a little on spool-down. Idle is 10
deg as Dan noted. What's rather puzzling is a> why there's
a dip in ignition timing like that around that certain
RPM/torque range -- backing off even farther sends it more
*advanced* again until you actually hit idle, and b> why
retarding the ignition at all would have any hope of being
efficient. Perhaps at very light loads, there's so little
mixture in there that it's not worth lighting it off earlier
since it's done burning before the power stroke is finished?
.
There is a little operational plateau in there with respect
to accel position. In that state I usually saw 14.5 degrees,
the iFCD hovering just under 100 MPG, 8 in-Hg of vacuum, and
4.4 or thereabouts ms injector time. So without the laptop,
my indicators of that state are the vac at 8 and the iFCD just
shy of 100 [sans scangauge, I can back off slowly and guess
when it just went off the top]. [Note that injector time is
usually 6 - 7 ms under most pulse conditions, and about 1.2
ms at idle.] The plateau shows up when wiggling my foot a
little through the 14-deg range -- the vacuum and RPM don't
increase or decrease. What does change just a little is
battery current. At lower demand I see about 5 amps of
charge, and at higher demand [just before vac starts to drop
and spark-timing changes] it goes back to 0. If I'm at 60%
SoC already the time that that 5 amps of "background charge"
happens is fairly short, and then the plateau more or less
disappears. That's when battery current [and the mimic] start
bobbling back and forth. If I've held the state long enough
for this to happen, chances are I'm down under 50 mph by then
and it's high time to pulse again. For what it's worth I
rarely saw 13 degrees, and if I did it was almost impossible
to maintain even if my foot was frozen. Must have showed up
briefly on transitions.
.
This is in keeping with how the Prius does a lot of its
engine management -- certain torque ranges are maintained
under varying demand, simply by shunting a little more
engine output to battery-charging instead of between the
MGs when needed. We see this pretty often at low speed,
too, when SoC is under 60%. If I backed off *too* far in
14-degree mode, the whole system just fell right into WS
by itself. So obviously this is how the Prius handles the
next demand region just above that.
.
So I can't see much MPG difference so far between this and
what I've been doing, but I've got the possible advantage
of being able to manage my WS a little more closely using
the battery-current meter and actually keep it close to
zero for long ones or use a little bit of 'lectric to sustain
speed without re-lighting until I need to. My 5-minute bars
wandered around somewhere between the 50 and 75 lines pretty
much the whole time, without any profound differences stemming
from either glide-mode. What still baffles me is how xcel is
pulling 80 MPG segments out of this where everyone else seems
to be working hard for 70. We're not worthy. No, the
aforementioned cinderblocks were *not* in the car.
.
I will note that holding the iMPG somewhere north of 75 was one
of the techniques I was trying two years ago. It was likely
similar to what's going on here. I couldn't see any profound
differences there either; of course I was doing a lot of that
in winter weather, so nothing was likely to hand me 70 mpg
highway runnin' for free. Bottom line that we've all known is
that the Prius ICE is pretty efficient in general, and the air
resistance curve is a bitch. We also know that trying to truly
steady-state at 55 - 60 mph is likely to see an efficiency drop.
.
But what I'm looking for is a higher "crossover point". If
I'm actually trying to get somewhere, it's nice to put a mile
a minute under the wheels and get the occasional thumbs-up from
a passing SUV instead of fists and fingers from all of them.
.
Side note -- my usual "S1 done" indicator is the change in
engine/exhaust note, which is pretty obvious and should
happen about a minute after startup anyways. I also see
propulsion begin to come from the engine instead of just
the battery, which has been causing me to try to take it
really easy on the go-pedal during that first minute to
avoid pulling the pack way down. 10-amp crawl out of my
road, and then pulse/EVB until it's warm enough for S4.
.
_H*

What still baffles me is how xcel is
pulling 80 MPG segments out of this where everyone else seems
to be working hard for 70.
Which is one reason I'm trying to pin down whether he is inducing it by some simple but very subtle pedal magic.

From the other thread ...

OK, got ignition timing plugged into the CV display. First observation is that it reports an ICE-off value of 19 rather than five. No significant driving observations yet, but hopefully it tracks linearly from there with how SG reports it, i.e., sweet spot = 28. If not, I should be able to duplicate Dan's discovery process easily enough and find the CV equivalent.

... an update: So two measuring devices (Autoenginuity and ScanGauge) are in agreement on IGN reporting, whereas Can-View is not. I might pass this on to Norm (the CV guy), though a lot of what CV reports is based on CAN decoding done by Atilla Vass (http://www.vassfamily.net/ToyotaPrius/index.html). Maybe it's just a simple arithmetic adjustment within CV.

Working on that assumption for the moment, I watched ignition timing on my morning commute today. Top speeds were only in the low 40s, but when I held IGN28 reasonably steady on the flat I was seeing RPM in the 1200-1300 range as reported by Dan and others, and iMPG at least in the 60s. Too short and too slow, though, for any conclusions yet about the SG/CV IGN relationship, but it looks like that might be in the ballpark.

There is a little operational plateau in there with respect
to accel position. In that state I usually saw 14.5 degrees,
the iFCD hovering just under 100 MPG, 8 in-Hg of vacuum, and
4.4 or thereabouts ms injector time.

CV reports injector time, so I'll set that up as another display parameter. EDIT: Just discovered that it's not available on the same screen as ignition timing, so I can't watch the two simultaneously. :(

Hi Dan:

___I saw IGN10 under a no arrow WS glide between maybe 52 and 43 mph on the way down yesterday morning if that helps add to your list?

___Personally, I do not think WS will beat the SHM in my experience given the way the Prius-II acts at a high SoC and while at these ridiculously low RPM’s. When or if I accelerate back up, I never come anywhere near IGN 18 unless needed for an emergency. I stuck to the IGN 13 – 16 and never pulled anything from the MGSet mimic as I instantly lose 1 – 3 mpg from a std. pulse no matter the rate at the time when running that hard an accel. I simply never pull from the MGSet for propulsion other then when in pure EV, EVER! I also tried not to P&G the SHM but maintain a relatively steady state – slower speed pace so as to let the 5-minute bars build and hold in the 72 – 73 mpg range while pulling full highway runs. SHM can be beat in some instances with active management using the iFCD, tach and mimic for some period but the 5-minute bars are not nearly so steady when pushing in that manner the way I am used too nor can the average guy or gal pull this off like half of us here do.

___Basjoos, the Prius is already pretty darn slick with a Cd of 0.26. The HP numbers needed at 50 mph with that low a Cd are miniscule so aero-modding would help only at higher speeds where SHM “may not” be as productive?

___Al and Jim, I cannot hold nor maintain 80 mpg w/ SHM. All the other techniques are needed including a healthy dose of warm up P&G before hitting the Interstate to put together a decent final result. From there, SHM slowly bleeds me until I find one of my favorite WS to Glide transition points along my route and take it down before a std. pulse back up to 50 +. This adds a few tenths only to let SHM bleed me down again until the next spot or traffic jam to really punch up a great 5-minute bar or two and so on and so forth. When I am speaking of bleeding, remember this is in the 80 + mpg segment territory that I am currently running or actively seeking. A 72 – 73 mpg, 5-minute bar just slowly bleeds you is all. Not like a 50 or 60 mpg one which kills me and yes, I have seen those early on with both the Prius-I and II :(

___What SHM offers everyone is a way to drive the Prius to high highway FE without having to actively manage more then one or two variables. They see IGN14 and they hold. It rises; they back off until they lock it in again. It just makes it easier for the average Jane and Joe to finally grab some decent highway numbers out of the Prius-I and II without resorting to the stuff we all have to do to pull the equivalent is all. It is pretty neat to see the Prius-II as large and heavy as it is cruising down the highway with the tach between 1180 and 1280 and while punching out the kinds of numbers most would die for :D

___Finally, there is something else about SHM that I never saw before. The SG-II is over-reporting FE per the iFCD parameter vs. the Prius’ iFCD in real time and usually they are in lockstep or the SG-II is underreporting (WS and even steady state type numbers) just a touch! This was very unusual activity to see the SG-II over-report vs. the OEM FCD in real time while watching both for their tell-tale signs. It was almost like the Prius-II went lean like a lean-burner at IGN14 and the SG-II did not know how to account for it other then think it was a regular instantaneous reading? The FCD was not 4 over actual like the first short and second full tank but under-reporting to top off. I think there are some more secrets buried in this IGN14 yet to be discovered.

___Here are a few pics (2 or 3 will go up in the Prius-II review I will be putting up someday) showing SHM in action. The following 4 pics were taken within 2 + minutes of one another and are in a time sequential upload from two nights ago during my last night into work with the Prius-II. The first pic was taken at 09:23 PM, the second at 09:24 PM, the third at 09:25 PM and the fourth at 09:25 PM.

http://www.cleanmpg.com/photos/data/523/SHM_in_action_-_Prius-II_review.jpg
http://www.cleanmpg.com/photos/data/523/SHM_in_action_2_-_Prius-II_review.jpg
http://www.cleanmpg.com/photos/data/523/SHM_in_action_3_-_Prius-II_review.jpg
http://www.cleanmpg.com/photos/data/523/SHM_in_action_4_-_Prius-II_review.jpg

___Holding onto 80 – 85 mpg on the highway is all but impossible but she bounces around between 65 and 90 during SHM a lot and I for one will take it. I have never seen a Prius-II driver come close to 70 with a mostly highway commute and SHM can possibly allow it if you can remove the warm-up hit with an EBH and plenty of P&G before hitting the interstate.

http://www.cleanmpg.com/photos/data/523/Final_short_tank_segment_-_82_2_mpg_-_Prius-II_review.jpg
Final short tank segment after 110 miles on Monday morning.

___Jerad and Marc, although SHM benefits all Prius drivers out on the highway, it will come nowhere near what your std. P&G offers in heavy traffic, city streets or out in the country. She just doesn’t offer that much on the highway so please do not go burn a half gallon just to see it while you guys are nursing 1K tanks. Wait for the chance when you have to drive the highway and then it will show you what a Prius-II can do without resorting to the usual counteracting of every move of the iFCD. What may be helpful however is while watching the IGN parameter during that last night and last morning yesterday before Cheryl took her back, I saw my std. Pulses lineup with IGN14 almost exactly during a P&G routine with my new found love for 5 or 6-bars of SoC. The following is just to show you what circling O’Hare on Monday morning during the Labor Day Holiday weekend with crazy traffic all-around will allow while running a std. IGN14 pulse but with short pulse durations to conform with 0 - 30 again and again and again.

http://www.cleanmpg.com/photos/data/523/Final_Short_tank_at_O_Hare_-_Prius-II_review.jpg

___P&G still kicks everyone’s @$$ in real traffic no matter what they are driving other then a PHEV/BEV including the 10 best Insight pilots on the planet so make sure you guys are willing to lose some just to see this new technique and parameter including what it can and cannot offer to you at highway speeds is all. When I look back at the Prius-I review and the Prius-II this past week, getting both into this high SoC range and nursing it for all its worth must place them in IGN14 without having known this parameter locks it down afterwards. There are too many similarities in FE and activity of the SoC, iFCD and aFCD’s in both over their 70 + % highway segments and tanks for it not to have been accounted for with a healthy dose IGN14 leading the way.

___Good Luck

___Wayne

___Basjoos, the Prius is already pretty darn slick with a Cd of 0.26. The HP numbers needed at 50 mph with that low a Cd are miniscule so aero-modding would help only at higher speeds where SHM “may not” be as productive?


Even though the Prius starts out will a fairly good Cd, there is still a lot of room for improvement, particularly if you want to try to get 70mpg @ 70mph. For example, I've looked at my Dad's Prius II and noticed it exhausts its hot radiator air under the car just like with any other car and its underpanelling is still very rough with lots of corrugations, gaps and seams, so there is lots of air turbulence under the car. My car has a totally smooth underpanel, exhausts its radiator air through the front wheel wells and the extended low-pointed rounded nose allows mostly laminar air flow under the car with the turbulence coming off the back of each front wheel confined to a channel between the two side skirts I have on each side of the car. And there are many other areas where the Prius aero could be improved as well, even if you don't go as far as installing a boattail. I had a recent discussion at the Gassavers website of possible Prius aero improvements with a Charleston area Prius owner who showed an interest in aero modding his new Prius to improve his mileage.

My CanView observations today agree with Jim's...not sure I saw a value below about 18 today and typically showed mid to high 20s even at ICE rpms in the 1200 range.

Jim, if you send Norm an e-mail let him know we agree on the numbers...I wonder if we're looking at exactly the same things... the CV Ign shows BTNC (degrees)...not sure what that means.

My CanView observations today agree with Jim's...not sure I saw a value below about 18 today and typically showed mid to high 20s even at ICE rpms in the 1200 range.

Jim, if you send Norm an e-mail let him know we agree on the numbers...I wonder if we're looking at exactly the same things... the CV Ign shows BTNC (degrees)...not sure what that means.
Isn't BTDC? As in Before Top Dead Center?

I e-mailed Norm, and here is his response:

"Hi Jim, looking through my notes I see I used the ignition advance as reported by the CAN message as the "number in steps of one-half degree with an offset of 64 to cover negative numbers". In other words it would read from -64 degrees to +64 degrees, although it would never actually reach either of those limits.

I remember at the time having discussions about whether this was true for the Prius or not and we ended up with the current calculation. It is certainly true for conventional vehicles, but there was some evidence to suggest it was different for the Atkinson cycle. I forget why it was such a drawn out argument now....

Basically my advance displayed will be exactly 14 (yes the magic 14) higher than scangauge shows. So if _temporarily_ you aim for 28 instead, see if that does what you want. If it does I can change all the displayed values in all the CAN-view versions to this new value and just ignore why the argument came up in the first place a year ago."

Basically my advance displayed will be exactly 14 (yes the magic 14) higher than scangauge shows. So if _temporarily_ you aim for 28 instead, see if that does what you want. If it does I can change all the displayed values in all the CAN-view versions to this new value and just ignore why the argument came up in the first place a year ago.[/I]"
Well that sorta make sense now with our observations...
I think I'm gonna propose to Norm...he's such a good guy.

Well that sorta make sense now with our observations...
I think I'm gonna propose to Norm...he's such a good guy.Kinda... I think CV is reporting the number of half degrees, and SGII is reporting the number of whole degrees. You want 12.5º - 14.5º or 25hd - 29hd (where hd is half-degrees). The closer to 14º (28hd) the better.

So divide by two instead of subtracting 14...

I think...

11011011

Kinda... I think CV is reporting the number of half degrees, and SGII is reporting the number of whole degrees. You want 12.5º - 14.5º or 25hd - 29hd (where hd is half-degrees). The closer to 14º (28hd) the better.

So divide by two instead of subtracting 14...

I think...

11011011
Makes sense for the value of 28, but not for the ICE-off value of 19.

Makes sense for the value of 28, but not for the ICE-off value of 19.I verified with SGII. I sent 010E using the CMDS. This is supposed to get IGN. To get º past DTC the math is to take the return value, divide by 2, then subtract 64 from the result. So when I sent down 0104, I got back 410E8A. The return value of 0x8A is 138. 138/2 - 64 = 5. Sounds like Norm divided by two and subtracted 50. 138/2 - 50 = 19.

Either way it works out the same for you. Off by 14.

Here's a reference on the math (http://en.wikipedia.org/wiki/OBD-II_PIDs) but I think I got it right.

11011011

Ahh, divide then subtract. Thanks, Dan! I don't know if Norm is following this thread -- I sent him the link -- but I'll e-mail him with your findings and Evan's CV results.

I looked into the RPMs on my SGII when in the SHM state and here is what I saw. Keep in mind, this is rough as it's only been two trips on the highway for about 6mi each way [with the sun in my eyes]

IGN - RPM
18 - 1600+
17 - 1500+
16 - 1400+
15 - 1300+
14 - 1200+
13 - 1100+

It seems to indicate RPM = ((IGN - 2) * 1000)

These numbers seem fairly consistent when maintaining normal driving conditions. Hills will change the RPM a bit, but for the most part this was fairly accurate on my trip. Not sure what others have found though.

Also, I will say that the IGN of 14 and 15 seem to give about MPH * 1.25-1.5 as was suggested originally. I have to say I haven't see 75-90mpg on the highway too often, but I rode in that state for about 3mi today while within 5mph of the speed limit.

I also used the IGN as a guide for acceleration now, instead of RPM. This seems to provide the most accurate means of finding the ideal acceleration point for P&G sessions. I try to keep it inbetween 16 and 18, but to get up to speed quicker 18 is the best bet.

I will do some more research in the next few days. I'm slated to meet with JimboK tonight, so I'll be on the highway a bit longer than a I normally am, and thus can pay more attention to the numbers.

May be mentioned earlier in the thread, but there are some interesting initial IGN numbers during S1....I showed a reading of 3 to 4 (CanView)....so -10 to -11 if sgII? It immediately jumped to the normal range as soon as S2 started and never fell below 19 (5 on sgII) again.

I think I need to read up on what these numbers actually mean mechanically...

Ignition timing is a pretty straightforward thing, and we know
the Prius runs quite retarded in S1 -- late ignition keeps the
mixture burning later and still plenty hot as the exhaust valve
opens, allowing all that hot gas to go down into the catalytic
converter and rapidly bring it up to temp. After that first
minute, it's done and reverts to normal before-top-dead-center
timing which actually lets the engine run right!
.
_H*

I'll have about 700 miles of highway driving from tonight through the weekend, I'll report findings on monday.

I'll have an almost clean 250 mile run on 55 mph roads on saturday, are you suggesting ign 18 to 55 then ign 14 down to 50?

Any other patterns that you would like to see tested?

Hi Sup’d:

___I wouldn’t run IGN18 up to anything other then when something is coming up from behind fast. Take it easy on the accel and the Prius-II will reward you kindly. It did for me anyway?

___A nice tire pressure increase and a fresh change to Mobil1 0W-20 synthetic certainly did not hurt either on this brand new Prius ;)

___Good Luck

___Wayne

I'll have about 700 miles of highway driving from tonight through the weekend, I'll report findings on monday.

I'll have an almost clean 250 mile run on 55 mph roads on saturday, are you suggesting ign 18 to 55 then ign 14 down to 50?

Any other patterns that you would like to see tested?You got it. Feel free to pick whatever pulse entry and glide entry target speeds you want. 55 and 50 are good, so are 60 and 50.

I find best numbers when I let the terrain guide me. This is kinda an art. You see a hill coming up and your half way through your glide. I'll usually break out of my glide and charge (pulse up) the hill so that I hit the top right at my glide entry target speed. That way I get a nice long glide down the end.

Now if that hill has another one right behind it, then I would go down the back side in a WS glide (IGN5) instead of a SHM glide (IGN14). Reason being that your probably gonna have to pulse up the hill anyway, and since WS glides are shorter, you can get a full WS glide before your pulse instead of half of a SHM glide.

I'm trying to use SHM as another highway tool for when I have a long strech that I can glide. Ironically, I don't use SHM on my commute because all the hills are timed perfect for WS glides :o.

So let the terrain dictate whether you use SHM glide, or WS glide. As far as pulse up, I pulse up at 18, I think Wayne uses a less intense pulse.

This is not the gospel though, I'd poke around and figure out what works best for you. My highway numbers are not in the 70's consistently yet, so I'm still in training on this stuff.

11011011

I'm slated to meet with JimboK tonight ....
A little off topic, but Tek and I met tonight for the first time, after some good e-mail dialog over the past couple of weeks. I'll let him supply a more detailed intro as he sees fit, but he's a fairly new Prius owner. More to the point, he's a programmer that really wants to dig into the car and the data like ... (gulp, should I say this??) ... Dan! :D

Dan, I told him the two of you should really enjoy chatting. ;) Now, I just need to learn the language you're speaking. :confused:

Had some highway driving today on my way to pick up my new FEH :D.

Since they sold it while I was on my way I had a long soulful drive back :(.

Being kinda bummed as you'd expect I could care less how my tank average suffered, so I decided to do some testing, and found out some neat stuff.

Check it out... DWL based on IGN 15 @ 55mph & 68mpg

http://www.cleanmpg.com/photos/data/500/dwl_ign15.JPG

Now that's a highway castle I would have killed for a year ago! So here's what I saw. Keeping IGN pegged at 15 (or anything) I saw RPM all over the map. RPM would drop as I slowed down (going up hill) and rise as I speed up (going down hill). The IGN wants to chase the RPM's up or down so you will have to ease up (a hair) on decent, and add pressure (slight) on climbs. The cool thing is that this feels a lot more like a "don't move your foot" approach. My position on the gas pedal was darn near rock solid while trying to hold IGN15. Worse driving cramps ever.

So here's a WAG on DWL average speeds as they map to IGN:
__IGN__|__Avg MPH__|__Avg MPG__
13.0|45|80
13.5|47|75
14.0|50|73
14.5|53|70
15.0|55|68
15.5|57|65
16.0|60|63
16.5|63|60


Again, this is a guess but I think it approaches what everyone is reporting. If my understanding of ignition timing is correct (not sure it is), there should be inherent inefficiencies (albeit small) that are introduced with changing ignition timings while driving. What I find interesting is how much RPM varies with a constant ignition timing as speed varies.

So (assumptions on assumptions here) it's possible that DWL when holding RPM may be causing IGN to bounce around a lot, introducing loss. What surprised me honestly is how constant the castle bars were when using DWL on IGN. That and the fact that it really is feedback on how to keep your pedal position rock solid.

Anyway 65 @ 65 may not be possible, but 60 @ 60 may have a chance at happening.

Edit: For the above, AC on AUTO at 77 headlights on.

11011011

In my first run last night 110 miles avg 53 mph, mfd showed 57.0 mpg. Night driving (how much of a fe loss are the hid lights?), 53/51 psi, and I'm in a touring model with the bigger stock tires.

I maybe only had 10 miles in the ign 14/15 zone, traffic was constant so getting the long bleed offs wasn't safe after dark. The hardest part to get was transitioning to ign 18 speed up without shooting rpms up above 2000. It seems like is it takes two adjustments, first hit tps 22 or 23 to get rpms to 1600/1700 then adjust to get ign 18. If I went to ign 18 first, everything opened up and I was over 2000 rpm.

I noticed that ign 18 / tps 22 had about a 1:1 mph/mpg ratio in the low 60 mph and is easy to hold once you get in that spot with a slower bleed off than ign 14 at below 55 mph.

I had the absolute worst driving pains of my life, making millimeter sized adjustments to hold an ign/tps(rpm).

Dan I think you can hold an rpm at a given ign, if you monitor tps to hold that and ign at the same time (for double the foot pain).

So here's a WAG on DWL average speeds as they map to IGN:
__IGN__|__Avg MPH__|__Avg MPG__
13.0|45|80
13.5|47|75
14.0|50|73
14.5|53|70
15.0|55|68
15.5|57|65
16.0|60|63
16.5|63|60

Anyway 65 @ 65 may not be possible, but 60 @ 60 may have a chance at happening.


In the last two days I've had way more highway driving possibilities than I would like, but in doing so it has given me alot of time experimenting with SHM.

The information above that Dan posted is pretty much spot on from what I've been seeing.

I was sitting in the 50-60mph range running about 65mpg on average.

I did some further experimentation with WS P&G versus SHM and it's really difficult to say which lends the better MPG.

The MFD MPG definitely moves up more quickly when doing WS, but I am guessing during your pulses you will likely even this out over time. In addition it should be noted that maintaining a WS glide cannot be sustained for nearly as long as an SHM glide. So, that being said the SHM method should be much more fuel efficient.

I am still not entirely satisfied with my testing though. I started my trip at 70.3 and ended up at 69.3, then I had another hour highway drive and ended up at 68.6. So my average was about 64mpg and 66mpg on those two trips with 90% highway driving.

When you can get 80-90+ shown on the energy screen while on the highway it's definitely a good feeling. But again, watching the average MPG on the consumption screen it doesn't seem to go up very quickly, even when running at 80+mpg for several miles. Then a small half mile glide on the battery makes it jump up .1-.3.

Anyways, just some ramblings I thought I'd share on the subject.

I might take the Prius to the beach this weekend which will afford me about 300+mi of highway driving. Will report more then.

Anyway 65 @ 65 may not be possible, but 60 @ 60 may have a chance at happening.



Yup, sure is! My best tanks running this commute have been in the 61, 62mpg range while DWL around the limit of 60 that takes up most of my 20mi commute. Based on what I've seen, SHM is not all that different from what I've been doing except that I never get down to IGN14 because I drive too darned fast. But I've been doing almost exactly as Dan describes: find the right accelerator position and lock in. The only difference is that I use my tach as a reference point (aiming for 1500RPM @ 55, a little higher @60).

On the other hand, I did experiment a little with the other side of the equation: using SHM as an alternative to WS. To tell you the truth I started to go blind from staring at the SG display, and for some reason I just suck at pegging a particular IGN number. So I gave up on using the SG, but I did manage to replicate what you guys describe: FE around 1.5x speed (e.g. ~90mpg @ 60mph) while losing speed albeit **very** slowly. That tach sticks at about 1200RPM while this is going on. I used that in combination with shorter WS this morning and managed a trip somewhere in the 65mpg range, which is about par for a good morning commute.

I guess I don't see why this is revolutionary because I don't see the mechanism where significant energy is saved. It seems to me that the losses involved in WS (conversion losses through the battery) would be roughly balanced out by the inefficiency of running the engine at low load toward the bottom of the RPM range. I think speed (aero drag) is the biggest difference between what Wayne sees on the highway and what the rest of us tend to report, and engine load (which apparently has some relationship to the IGN value) follows speed.

Unless I'm totally missing the point, which is possible.

I'm tending to agree, and thinking that 70 @ 50 is fairly
attainable using a variety of techniques -- whatever's best
for the surrounding situation.
.
_H*

I'm tending to agree, and thinking that 70 @ 50 is fairly
attainable using a variety of techniques -- whatever's best
for the surrounding situation.
.
_H*Yep, I don't think this beats WS P&G, just found it interesting what type of behavior IGN could help illustrate. Plus I like having both short glide and long glide methods to draw from as the terrain dictates. I find I use them both

11011011

PS.. I'm looking at your spreadsheet data and it's very interesting. Thanks for all the help with this.

Hi All:

___I will tend to disagree per the following pics although I am traveling 45 – 65 mph limited Interstates vs. 60 + as some may be?

http://www.cleanmpg.com/photos/data/523/Prius-I_Review_tank_commutes_-_381_to_769_Miles_-_78_8_mpg.jpg

___That shot was taken from the Prius-I review. Throw out the last 3 5-minute bars because this is where the numbers were picking up fast after leaving the Interstate but the first 3 in each case were when holding this as yet unknown 70 – 90 mpg range while out on the highway. By holding to an IGN, it is a lot easier to maintain a high highway FE then moving into and out of WS unless the terrain dictates it. The Prius-II’s final few segments were higher, more stable and easier to achieve then when pushing with all the variables dancing all over the place and fighting with WS opportunities and pulses back up again and again. At least in my case it was and the Prius’ full and final tanks showed me much more promise as well as showing how this mode can be exploited by anyone with an SG-II vs. playing games with a higher end technique that only the better drivers can run for higher FE day in and day out?

___Good Luck

___Wayne

I'd tend to agree that until things like battery current
can be reliably observed on a SG, it's probably easier to
hold the 14-degree state. I'm biased, of course, because
I can use the current meter to hold WS almost indefinitely
but for most folks it's pretty touchy. Still, when I had
http://techno-fandom.org/~hobbit/pix/hf06/prewg_s.jpg
on the way home from HF06, it was from a mix of techniques
on secondary/slower highways but pretty heavy on the WS.
That's sort of when I began to discover its merits, I guess.
.
Dan -- any interesting conclusions from the big data-glob?
I haven't done much with it yet; sorted it and punted a few
odd outliers and noted a fairly reliable IGN / RPM correspondence,
but I haven't tried to graph it or anything yet.
.
_H*

Dan -- any interesting conclusions from the big data-glob?
I haven't done much with it yet; sorted it and punted a few
odd outliers and noted a fairly reliable IGN / RPM correspondence,
but I haven't tried to graph it or anything yet.
.
_H*Yeah, I'm working out a scalar efficiency quotient. I figure that MPG/RPM should be pretty linear to MPG. Off by some coefficient. Anyway I'm using it to work out a moving average to try to verify my WAG on IGN to MPH to MPG steady state guess.

11011011

I ended up averaging 64 mpg on 300 miles of proper conditions to practice this on @ 52 mph avg.

I monitored ign/tps/rpm for the entire 700 mile trip.

14/18/1280 = 75-90 around 50 mph
14/17/1220 = 95-99.9+ ife around 50 mph
14-16/16/~1180 = ife pegged at 99.9 (I got here about 4 or 5 times and I was able to hold for ~30 seconds each time)

I could get it into any ign >= 14 at any rpm by making two pedal adjustments, I cruised at 70 mph at 2200 rpm / ign 14 for 5 minutes on flat ground (ife 50) so I disagree on the average mph by ign column in a chart in a previous post, needs rpm as an input.

Thanks for discovering this, now I have the tools I need to apply them in my commute. Today my highway segment bars were 3-4 mpg higher than normal.

If someone finds the ign/tps/rpm combination for the optimal speed up rate that would be great to know.

66.4 RT from Austin to Houston! Woohoo!

First off, I enjoyed meeting Dan, seeing Chuck again, and meeting some of the others at Dan's HHH club. We all took pictures for the HHH thread.

The 150 mile trip is all US non-interstate highway, with just a few short lower-speed P&Gs through towns. It's a 700 foot drop from my house to the meetup in Houston.

I started out as a SHM novice, and tried to keep her within a 55-62MPH band. On the flats, SHM. On hillier terrain, DWL/WS. Average speed for the entire RT was 52mph, average speed while actually on the highway itself probably closer to 58.

On the trip to Houston, I found it somewhat difficult to actually peg 18 & 14, and often found myself living with 19 & 15, or slipping accidentally into a WS 5. Arrived in Houston at 66.7.

But wow, the trip back just didn't want bleed that number at all! Back to Austin was a solid 66.2, giving me the 66.4. I attribute this to just slightly slower speeds back uphill, plus my improving ability to consistently peg 18 & 14.

My trips to visit family in College Station are a similar distance, direction, & terrain as this trip to Houston. My best RT to College Station was right at 60. That trip was DWL/WS on the hills, steady state on the flats. So SHM instead of steady state seems to give me a 10% bump.

Like others here, I question whether SHM is preferable to DWL/WS. For that reason, I'll continue maintaining DWL/WS on hilly terrain. But I just love SHM for a whole host of practically reasons:

(1) It's easier to pull off than DWL/WS on the flats. The quick deceleration of WS combined with the required complete removal of my foot from the pedal is too much work for me on the flats. On the trip back to Austin, I found myself actually maintaining my heel position and starting to shift the pedal position exactly from 18 to 14 and back again for long segments.

(2) Pegging one IGN number is easy, which makes it a usable tool for the less sophisticated. Just drive in a band and peg IGN.

(3) IGN14 on flatter stretches with a slow decline is coooooooool. Holding 100+mpg at 55mph for 3 miles without losing speed makes me briefly think I've got myself an insight, before the next incline brings me back to reality. ;)

(4) I'm done "apologizing" for the Prius on the highway!!! The car is often a topic of conversation, and like most of you I inevitably have to get into discussions about the phenomenal city performance vs. the "fantastic but not quite phenomenal" highway performance.

Well, I'm feeling increasingly confident now saying that "approaching" 70mpg highway for the average instrumention-equipped driver is actually a possibility with (1) slower 55mph speeds, (2) good conditions, and (3) working hard, and for me that puts the Prius on the lower end of "phenomenal" instead of the upper end of "fantastic". The Prius has moved in with the Insight? Yes, the Insight owns the HW house and sleeps in the master bedroom, while the Prius is renting the guest room. But are they now in the same residence? :)

Marc, Killer HW segment there. I consider any HW over 65 phenomenal.

Something I was messing around with in post #36 of this thread was using an IGN of 15 as your DWL target. Hold IGN15 with the highest RPMs that IGN15 will allow. You have to chase it for a bit, so be patient. Once you have it dialed in, hold IGN15 with high (1300-1400 ?) RPM. This should give you an avg speed of around 55. For a bit more pep try DWL at IGN16. I think both should hold you over 65mpg at a fairly decent speed, assuming elevation stays fairly steady.

Watch out as your speed varies (nature of DWL). Slower speeds tend to bring IGN down forcing you to get on the throttle to hold the number. Higher speeds tend to push IGN high. Once you fall off, you may be in one of the "wierd zones" where IGN increases as you reduce throttle or IGN decreases as you increase throttle. Agian, just chase it around for a few secnods, eventually it comes to its senses.l

11011011

I've done several part time gigs not far outside of town the past couple of weeks, with RT drives from 50-110 miles. These have been good opportunities to explore SHM.

First, an explanation/disclaimer: As many of you know, I'm running with fairly new Hydroedge tires. I estimated a 5-10% FE hit when I first put them on. I've probably recovered some of that now after 6000 miles, but nowhere near the full amount. Oh, to have well-worn Integritys again! :(

I have a number of route options that mostly keep me off the interstate. They're mostly country roads, some 4 lanes and others 2. Depending on time of day and day of week, I may have a lot of company or practically none.

I've been managing MPG in the low 60s for the most part. Average speeds have been in the low 50s on the open road, with lower speeds on some of the more narrow and twisting roads or on short segments through civilization.

Yesterday was better. The outbound route was probably the flattest I've found yet, and traffic on these roads was considerably lighter than on the previous early-evening weeknight trips. The first half saw 67 MPG. I filled up at about the halfway point, and here's the MFD on arrival at my destination:

http://www.cleanmpg.com/photos/data/500/MFD_9-23-07_A.JPG

The peak and valley in the 2nd and 3rd bars are mainly from a descent for a bridge crossing and the climb on the other side.

The first half of the return trip was mostly on a different route -- somewhat more hills and traffic, but more direct. (I was tired at 10:30 last night and wanted to get home.) The second half was mostly the same route as the first half of the outbound route. Here's the MFD not far from home.

http://www.cleanmpg.com/photos/data/500/MFD_9-23-07_B.JPG

The pegged bar was for a brief drop in PSL to 35 MPH, allowing P&G.

I'm confident the overall tank number would have been better if I had retraced my steps the whole way.

Some observations and comments:

As others have suggested, SHM is likely better suited for terrain that's flat or nearly so. You certainly can't hold IGN14 and low RPM on a moderate sustained uphill without slowing to a crawl, and the downgrade on the backside may force you to use WS, if not outright regen, to stay safe and legal.

I've been wondering if we're complicating things a bit by focusing on IGN values. Could it be that all we're doing is simply keeping RPM as low as possible? Yesterday I focused more on RPM than IGN, keeping it right around 1175-1200 whenever possible. (Much below that and it drops into WS on its own.) A brief periodic glance at IGN generally showed it to be around 27-28 (remember its offset of +14 with SG), with the lowest value, IIRC, at 25.

With either parameter and on unchanging terrain, whether flat or a gentle incline, you can keep the readings steady with steady pedal pressure. It's seems it's a little more of a challenge when terrain changes. As Dan (I think) says, you may have to chase the target reading a little, but that seems to be with either reading. At least with RPM you can anticipate changes based on upcoming terrain changes, and with practice you can time pedal adjustments accordingly. IGN, on the other hand, seems to change more abruptly and less predictably.

Anyway, using RPM as my primary guide, I got results on the flat similar to what Dan, Wayne, and others are reporting: speed decaying ever so slowly while iMPG sustained itself at least in the 70s, routinely in the 80s, and sometimes in the 90s and low 100s. Dan reported that SG may refresh IGN a step ahead of RPM, so that may guide SG users on which to monitor. RPM and IGN update simultaneously and nearly instantaneously in Can-View.

Where high iMPG numbers sustain themselves seems to be related to ever-so-subtle changes in incline. I could tell I was on a (nearly imperceptible) downhill by the fact that speed remained constant, and that's when iMPG approached and crossed the 100 MPG threshold. On a more noticeable -- though still slight -- downhill, they could creep into the 120s and 130s. A slight uphill brought about the predicted faster speed decay and lower iMPG readings. All of this while holding ~1200 RPM. I would push it higher only when I dropped below about 40 MPH, to get up the significant hills, or to keep at bay what few cars approached from behind on the 2-lane roads.

All of this is with 60%+ SoC. I've sought to stay out of the battery as much as possible. In particular, I've limited the use of WS (except for anticipated slowdowns to sub-40 MPH levels), using it, along with regen, more as a speed-control mechanism on steeper downhills than as a FE-booster.

Excluding the 5 minute bar in which I get up to speed, I've been consistently getting 75 mpg 5 minute bars for the 15 mile highway segment of my drive keeping mph minimum 50. I've mentioned it before, but monitoring ign along with tps makes it much easier to hold and find the sweet spot with sgii, I can get the 14/17 (90+ ife) within a couple of seconds of the top of a pulse and can get into and hold the 14-16/16 (pegged at 99.9) with slight decline in the road from the 14/17 state making extremely small adjustments to the pedal. For me it is easier to watch a two digit number instead of the 4 digit rpm.

Sup'd, what kind of terrain are you dealing with?

One other comment. This part-time job is a limited engagement, with the last trip scheduled next week. My routine highway driving is otherwise infrequent. Where I have found this technique most helpful is for certain non-highway settings, mainly during my commute. On busy two-lane segments with PSL of 40 or 45 MPH, I know now how to run mostly at the prevailing speed, or maybe even a little faster, without much of an MPG hit. Previously I was trying to keep it at or below 40, often with brief bursts of pedal-feathered EV to maintain speed, or short periods of P&G as traffic allowed. But traffic and terrain would often force higher-RPM bursts, likely negating much of the benefit of P&G and EV. Now I just accelerate modestly up to speed and mostly keep it there with these low RPM/IGN values.

These segments are too short to practically measure and compare, so I can't say for sure what the effect on MPG is. But total trip MPGs don't seem to have suffered, so I am confident the hit is minimal, if any. And others are happier while I'm playing in traffic. That's an acceptable tradeoff.

I have an out of town trip scheduled in November in Norfolk, about 2 hours east of here. The route I take (US460, for those familiar with the area) on this trip is rather flat, 4 lanes, not heavily traveled, and mostly 55 MPH, with brief drops to 45 in small communities. This should be an ideal situation for SHM, and I'm anxious to try it there.

On the route where I've been practicing, it is rolling elevated highway with a few segments where I can hold the pegged 99.9 for a minute or longer.

My general method is to either be in an 80+ state or accelerating at around 40 mpg until I get back to where I can switch to the 95+. I try to keep mph above 50, unless I have a big gap behind me and take it down to 47.

I've got a 300 mile trip to the Mexican border in two weeks to visit some college buddies. Traffic is usually pretty sparse, so it'll be a good opportunity to pull out the SHM (& other) tools.

It's a 700 foot drop over 300 miles to the border. That plus less traffic plus my slower speeds may just allow me a run at 70 for the downhill trip (we'll see about RT).

It's 855 miles along I10 from El Paso (NM) to Orange (LA). 855 / 12.1 gallons (assuming you can squeeze in 12.1 before immediately driving and burning it off) = 70.7mpg. I think I could just pull off the state of Texas if I kept her around 55mph. Makes me want to go fundraise/promote the cause with media & such. Oh honeyyyyy........ ;)

I was playing around this morning and made a couple of observations that I don't think have been mentioned. In particular I was looking at what the system does when you apply throttle to get to your target pulse or cruise rate vs. overshoot and come back down.

Letting off the throttle at highway speed seems to result in higher iFE for a given engine RPM. In other words it looks like this results in a somewhat less throttle and higher RPM to give you the lower power requested. As a rough data point, this seemed to be putting me at ~1600RPM to maintain a 55-ish MPH cruise.

The really interesting thing was what happened when I did the opposite: very carefully increase throttle pressure to my desired pulse/cruise power without overshooting and having to come back. This consistently yielded lower engine speeds (and presumably a wider throttle position, though I didn't have the ScanGauge plugged in) for a given RPM. As an extreme example, there's one stretch toward the end of the drive where I have to accelerate from 45 to 55mph up a slight grade in order to maintain the limits, and I usually do this at ~1700RPM for a leisurely pulse rate. I then lock-in at about 1500RPM or a little more to maintain the cruise. This morning I started from a WS glide and slowly applied throttle until I was picking up speed at a gradual but consistent pace. When I looked at the tach I was surprised to see the needle hovering at no more than 1250RPM. Was I getting assist? No, no power from the battery indicated on the MFD. And the FE was right about 60mpg, which is stupid-high for that kind of pulse. I held that configuration for a while but I got "stuck" at about 53mph, which was when my accel rate became too slow to hold on. Pretty nuts! FE for the morning run was about average, but I didn't start to get a handle on this until the latter part of the segment.

Good stuff Brick, I may do some playing & comparing on my trip next week.

It seems as though 53mph is a fairly significant highway speed. Wayne mentioned that he could hold IGN14 for a long period of time at 53, and your high iFE, low RPM, gradual accel seems to stall at 53.

As awesome as the car is, it sometimes takes me right up to the door but won't let me in. Glide on 45mph roads? Sorry, how about 41? High iFE steady state highway driving at 55-60? Sorry, how about 53? :)

It's the Dan Marino of autos. The PHEV will be Joe Montana. GM's fleet is Ryan Leaf. ;)

One more trip to my right-outside-of-town venue. Because of time I used the highway for part of the trip. The highway leg was about 14.5 miles of a total 33 mile trip. This highway is mostly hills, gentle but long. Speed there ranged from 55 to about 67 except for one hill crest where I dropped to about 50. Off-highway speeds averaged around 45-50, occasionally getting to 55.

(That was outbound. I used other more secluded back roads with several sustained sub-40 MPH P&G segments for the trip home, so I'm not considering that for this discussion.)

This time I ignored IGN and focused almost exclusively on RPM, with the goal of keeping it at 1175 once up to speed whenever possible. (Can-View rounds off engine speed to the nearest 25 RPM.) On the highway uphills, 1500-1700 generally kept me at a safe speed.

It seemed like I could do no wrong. On some of the highway downhills I saw iMPG as high as 150+. On flatter segments I could still often stay above 100. Only when I started climbing did it approach 50, but I could still mostly keep it there or above on the highway hills.

During one relatively flat off-highway segment, engine speed was at 1175 while vehicle speed was in the low 40s; iMPG was in the 70s. I locked my foot on the floor to hold the exact pedal position, and the numbers stayed put, probably for a couple of miles, until the next uphill.

Other off-highway segments with speeds in the 50s would routinely show iMPG readings in the 80s and 90s. Not sustainable on the flat, as we've already discovered, but speed decaying slowly enough to maintain the low RPM potentially for miles.

I've been playing a bit with the brief pedal adjustments that Brick describes, both on these rides and my normal commute. What seems to help me is a brief off-then-on sequence with the pedal. (Maybe that's what Wayne was describing in his original thread.) iMPG seems like it jumps by 10-20 with comparable engine speeds.

Results: 68 MPG for the trip, including the warmup. It should have been well over 70 if I had reset the trip readings after the warmup. Here's an MFD shot at the destination:

http://www.cleanmpg.com/photos/data/500/MFD_3-10-07.JPG

This reinforces -- for me anyway -- my theory that the key to SHM is low, sustained engine speed. Those that would choose to monitor IGN have given good reasons for doing so, but I think I'll stick with RPM. At least until Wayne borrows another NHW20 and finds yet another hidden secret. ;)

Now, whether SHM beats higher-RPM pulses and WS is still open to debate. I'd like to do a controlled test; maybe I'll do so after I get moved into my new house. But I am convinced, as I suggested earlier, that SHM is better suited to terrain that's flat or nearly so, if only because of steadier speeds that are less likely to irritate other drivers.

Great stuff Jim. Did you have any net elevation change and/or was the AC on?

I've got my own 300 mile trip this weekend. Someone is coming along for the ride, so AC will be on (low) and speeds will probably be higher than 55. But in my mind I was aiming for something like a RT "63mpg @ 63mph average" with the AC on low setting. If you had the AC on low and the trip was flat, then your "68 @ 61 average" makes me hopeful I can impress. :)

I get the feeling from reading all experiences that all things equal:

(1) SHM can give you a 10% bump
(2) SHM executed like a pro can give you a 15% bump

The guy coming along for the ride is somebody with both $$$ and highly motivated by the world around him......someone with the potential to go "wow, I had no idea.....I'm getting me one of these." ;)

Great stuff Jim. Did you have any net elevation change and/or was the AC on?
Good questions; sorry I omitted the answers.

AC was off. Windows were opened enough for driver comfort.

There actually was a small net elevation increase, maybe 70' or so. Surely not much of an impact, but I was still pushing uphill.;) See this (http://www.gmap-pedometer.com/?r=1367252) for a map of the route, including an elevation profile.

Not sure if it was "68 @ 61." In fact I'm pretty sure my average speed would be considerably lower when you factor in the turns and off-highway hill climbs. But that's something else I'll track if I do any controlled tests.

Just wanted to pop in and thank you all for the great work you do on this site. I just got my sgii and I'm anctious to try the SHM technique on my commute home tonight. I have a couple of 2 to 4 mile segments where 50-60 mph highway speeds are possible. The only problem is that terrain is anything but flat and it's only a 2 lane road. I suspect I'll mostly be employing the IGN18 pulse and 14 "glide." I'll also try to play around some with this technique over the weekend and will try to update on Monday. I can usually get about 55 - 60 mpg on my commute home (depending on temps - need to block the grille this weekend too now that I can monitor wt) so we'll see if I can improve on that.

Just wanted to pop in and thank you all for the great work you do on this site. I just got my sgii and I'm anctious to try the SHM technique on my commute home tonight. I have a couple of 2 to 4 mile segments where 50-60 mph highway speeds are possible. The only problem is that terrain is anything but flat and it's only a 2 lane road. I suspect I'll mostly be employing the IGN18 pulse and 14 "glide." I'll also try to play around some with this technique over the weekend and will try to update on Monday. I can usually get about 55 - 60 mpg on my commute home (depending on temps - need to block the grille this weekend too now that I can monitor wt) so we'll see if I can improve on that.

It takes a little bit of time for the computer to figure out what you're trying to do, or for you to figure out how to tell the computer what you're trying to do. So keep at it and you'll be flowing in and of it within a few hundred miles of practice.

You want to try to transition to ~1600 rpm and ign 18 from the ign 14 state when you need to pick up speed, when I first tried I was getting 18/2000+ so its not just ign 18.

Just wanted to pop in and thank you all for the great work you do on this site. I just got my sgii and I'm anctious to try the SHM technique on my commute home tonight. I have a couple of 2 to 4 mile segments where 50-60 mph highway speeds are possible. The only problem is that terrain is anything but flat and it's only a 2 lane road. I suspect I'll mostly be employing the IGN18 pulse and 14 "glide." I'll also try to play around some with this technique over the weekend and will try to update on Monday. I can usually get about 55 - 60 mpg on my commute home (depending on temps - need to block the grille this weekend too now that I can monitor wt) so we'll see if I can improve on that.
Hello, Highly! Good to see you here after several "PriusChats." ;) Good luck with the SG; you're gonna love it.

Thanks for the tips sup'd and the encouragement Jimbo. The SG is great, but I just have to keep reminding myself that focusing on the road is more important to my health!

I was able to get about 60 mpg on my ride home on Friday with temps in the lower 50s, which is on the high end of what I was able to get over the summer. I got about 53 mpg on my ride in this morning, which is also close to my summer best and it was 37F out (had the upper grille blocked). My commute is about 22 miles each way and there is a significant elevation change, so I always do better on the way home than coming in. In other words, so far so good. I'm sure it will only get better as I keep practicing.

Even though the Prius starts out will a fairly good Cd, there is still a lot of room for improvement, particularly if you want to try to get 70mpg @ 70mph. For example, I've looked at my Dad's Prius II and noticed it exhausts its hot radiator air under the car just like with any other car and its underpanelling is still very rough with lots of corrugations, gaps and seams, so there is lots of air turbulence under the car. My car has a totally smooth underpanel, exhausts its radiator air through the front wheel wells and the extended low-pointed rounded nose allows mostly laminar air flow under the car with the turbulence coming off the back of each front wheel confined to a channel between the two side skirts I have on each side of the car. And there are many other areas where the Prius aero could be improved as well, even if you don't go as far as installing a boattail. I had a recent discussion at the Gassavers website of possible Prius aero improvements with a Charleston area Prius owner who showed an interest in aero modding his new Prius to improve his mileage.

link up the good stuff brew! i'm so down for cheap areo mods, since i travel on the highways from time to time with average speeds of 80km/h to 100km/h, anything more and i'm late for something.

But with my CANVIEW backing me up this is what I see when I'm on the highway...

1500 rpm pulse, speed climbs 1 km/h per second (if drafting that number decreases to .7 per 1 km/h)


glide eating away from the battery at 10 amps or 15-20 amps if your battery is in the green state, otherwise you can light the throttle some more and achieve prefect deadband (0 amps) but since your still using energy to spin the engine at 925 rpm (ok this is where things get werid, sometimes the ICE spins with no fuel consumed or consumes at .6L/hr if it does idle normally) the glide phase gets a negative energy balance epically if you consider the losses to areo and all that jazz.

for comparison under 64km/h deadband is a mere 1 to 3 amps on the energy screen, anymore and you'll see the yellow arrows on the screen.

On the highway when pulsing at 1500 rpms, amps to the battery can vary from .2 amps to 10 amps depending on SOC what I noticed is between 54% and 64% amps can vary on those two numbers i gave, depending on demand load so its very possible to direct most of the engine power to the mechanical path. However, as soon as SOC is under 53% that's where amps are going to rob your mechanical pull, which ranges from 10 to 15 amps and anything over 15 amps I notice is when rpms are much higher than the desired efficient range (above 2500 rpms)

Doing the pulse towards a huge truck and then glide behind him on highway speeds has netted me 20 minutes of 2.5 L/100km segments (the first 5 minute one being 5L/100km with EBH), I've never personally done the test on open air due to if that situation arises I rather cruise at a constant 1500 rpm ignoring speed (since no one is behind me). But as soon as a vehicle is in front of the lane I'm in, its time to reap the benifits.

I look at the CANVIEW on the daily basis, and boy let me tell you, the prius has some interesting numbers. Now I'm on the hot debate if I'm going to trade in for a volt or just save up for a a123 phev conversion, although the 55 km/h speed limit is a sure turn off but the mpg efficiency is almost the same @ 150 mpg of gas/electric.

I still think 1500 is just a tad too low, and starts bringing
torque off the engine. My minimum these days is usually around
1700, or just go to WS if that's pushing too hard. Gave up on
this "SHM" thing once I realized how it's such a small shave
above WS except that it's started to burn gas again, and doesn't
really keep me going any better than on-the-plateau WS itself.
.
At 1700 you're right about in that MPG == MPH region, the top
of that range described by JimboK as .5*speed - 1*speed -- this
really does seem to hold true over a fairly wide range of
operation, and lands pretty exactly at 1700 - 3200 RPM. So that's
how I'd highway sweet-spot in an uninstrumented car, I guess.
.
_H*

I still think 1500 is just a tad too low

trucks and big objects are your friends!

but i agree, sometimes 1750 (i find it easier to peg it there than 1700) just gets the car moving immediately, instead of holding 1500 for a longer period of time.

What i did notice and I do need to confirm, is that Break horsepower to the wheels varies on rpm (Assuming amps going in and out of battery is zero) it used to be 1500 rpms for 14 breakhorse but after changing from barely any tread to fresh tires the horsepower increased by a few points (17 now)

I'm skeptical, but i highly doubt new wheels will have horsepower gain, and yes I did keep the specs to the original 185/65/15's

OK, as just posted in the DG, I drove home for the Thanksgiving weekend. I had my 2 SGs all ready to go, flipped one of the gauges to TPS based on the discussion here, and was all set to lock in the 53MPH / IGN 14 / TPS 18 sweet spot that has netted highway segments of 70+ for some. Checked my tires right before leaving - still in the low 50s all around. I know conditions were less than optimal for a 70+ attempt - a weather system had just moved through dropping the temperature into the 30s and shifting the wind to be out of the north at 10-20 MPH, so driving basically NW I'd have a nasty little head/crosswind most of the way.

Well, as you might have guessed, things didn't go so well. IGN 14 / TPS 18 was simply not possible. With a completely open road I might have been able to stabilize speed at 45...MAYBE...with 14/18. Instead, I found that IGN 15 / TPS 21-22 was necessary to maintain 50-55 MPH. There were times when it worked pretty well - I was seeing mid-60s iMPG when I could hold it there and there was a good flat section of terrain. A "recal" of backing completely off, then slowly reapplying back to IGN 15 / TPS 21-22 was often good for +5 iMPG and a bit lower RPM, but this didn't always seem to work either.

Then there were the nasty hills on the secondary highway I was taking. 2400 RPM, IGN 19 / TPS 30, speed stabilizing around 40 (luckily most of these had a slow truck lane), and iMPG completely in the toilet. Down the backsides, either WS, neutral, or outright braking depending on length and steepness.

I did what I could to bring up the average going through towns (ah, reprieves from the wind :)) but it wasn't nearly enough to bring the overall trip up to where I would've liked to have seen it. 54.9 for the whole 263 miles of torture.

My extra grill blocking definitely had an effect, I saw peak coolant temps around 205 rather than 190-195. I'm not sure if that helped or hurt. I know in town it definitely helps.

Anyway, I guess I find myself wondering how much of this was due to conditions - would this have been 65+ at 70 degrees and no wind? 70+? ...and how much is due to my limited chances to mess with SHM and see it work to my satisfaction.

All I know is I need to learn all of the finer points in the next 6 months.

It's been 2.5 years and a bunch of wildass-theory webpages, and
I'm *still* trying to figure it out. You're not alone.
.
_H*

Hi Jerad:

___RR and air resistance has increased immensely since it was in the 70’s and 80’s so nothing works the same in 30 degree temps. You are probably seeing this with glides at the micro-speeds in the daily grind as well as anyone in anything at higher. Prius’ just like everything else are worthless in the cold :(

___As for SHM, 76 + over 1,600 miles in a Prius II with 70% LS highway was not bad using a subset of the technique in much warmer temps ;)

http://www.cleanmpg.com/garage/images/609.png (http://www.cleanmpg.com/index.php?page=garage&displayunits=MPG(US)&viewcar=609)

___Good Luck

___Wayne

Jared, I would say, from my experience with SHM, that you had some pretty bad conditions to work with. A couple of weeks ago when I made my last highway trip, I had temps quite a bit higher than you had and the wind wasn't nearly as bad either. I would say that you did well for what you had to work with.

Hi Jerad:

___What Larry said. The conditions you were driving in are in no way going to let you see anything but garbage no matter what you were doing including HS P&G, LS P&G, DWL and DWB or SHM. Nothing works worth a darn while in 30 degree temps in a Prius … or anything else for that matter.

___Before the GR, we will all have some clinic time to lock it all down. I am going to do everything I know to see all 10 vehicles in Paris with a > 53 mpg around the world.

___Al, I guess the best thing is I do not drive nor do I see the Prius’ instrumentation day in and day out. Every time I get in one it is a brand new experience and although it scares the hell out of me each and every time, those 70 – 90 mpg flashes you guys see can be maintained in some fashion using the high SoC - SHM at LS highway. At least that is what I experienced in 70 and 80 degree temps and it is the only way I know how to get there? There had better be some 100 mpg + stuff mixed in because although all segments started out from cold w/out the aid of an EBH. Using the DSG technique helped blunt the warm-up hit to at least 65 + mpg over the first 3 or 4 miles of ½ the segments.

___All said and done, the Prius hates the highway in our world but for everybody else, 50 + from a 2,900 + pound, mid-sized sedan is fantastic!

___Good Luck

___Wayne

Hmm, I guess it's both good and bad that maybe 55 is all I'm going to see with 30s or colder. Good in that there are all of these wildass theories out there and one doesn't seem to have a whole lot of edge on any other (meaning there is probably still some way to put it all together in a way no one's really come up with yet), and bad because...well... 55 sucks. :) I haven't seen a tank end at 55 or worse since february when we saw -15F here.

More torture in the form of a highway round trip today, netting 57.1 out and 52.2 back for a 54.5 / 66.3 mile RT. Guess which half the wind wasn't in my face. :rolleyes: And again this was racking up the train behind me because I was doing between 50 and 55 most of the way. How much worse would running at 60 with a "just drive it" mentality have been? (I don't know, because I refuse to see a <50 segment of any length (that doesn't bring S1 sucktitude into play) when it's still above 0.)

I haven't really watched for a correlation between SoC and how easy it is to hit a "sweet spot", but I do know that it tends toward 62.0 or 62.5% out on the highway, whereas in the city it makes obvious attempts only to keep it in the 5-bar range, 55% or higher. At 67% or higher (7 bars, which is very possible if I have an unavoidable stop from highway speed), on getting back up to speed it will leech SoC until it's again in that 62% range, and the iMPG will hang higher.

It feels like my entire strategy to this point is little more than a glorified DWL + modest acceleration (1800-2200 RPM) if my speed gets too low. And WS or neutral if I run into traffic or if there's a long enough downhill. But the DWL part nets me 65-70, the "modest acceleration" is 30-40, and WS/neutral helps marginally. It averages out to about 55. But no better. :(

Sounds like a freaky lean burn to me and very hard to control....

Hi Jeff:

___It is when approaching its limits (53 mph for IG14) but from 48 – 51, it is very lean burn like without the NOx purge.

___Good Luck

___Wayne

xcel:

I am able to get into the ign 14 state at any speed that I've tried, or are you saying that 53 mph is the limit at which it can hold/just barely hold speed? Above 53 I use the ign 15/tps 19 for the hold/slow bleed.

I think there is definite set of parameters of what the computer will let you go into at various speed and load conditions.

I don't think that the availability of shm is SoC dependent, as I can get into it at lower SoC when I need to. How long you can hold it and the rate of slow down I believe is SoC dependent.

Perhaps I should make a trip from downtown chicago to your location and show you what I'm seeing sometime.

Hi Sup’d:

___With the colder temps, SHM just like leanburn and even gliding is shot to hell due to RRC’s going through the roof. What you would see today is not what you would see next summer. You can run IG14 at any SoC but I saw the best results (70 – 90 mpg flashes and 70 - 75 mpg 5-minute bars) when the mimic started jumping between charge and assist in both the NHW11 and NHW20. At that point, the FE and speed at 1,280 – 1,3xx RPM could be held forever on the flatter terrain of IL.

___You have to remember, I only have a few thousand miles behind the wheel of the Prius-I and II and although I can find this activity, I do not in any way shape or form consider myself an expert as to its nuances. Prius owners are the ones that should keep digging but seeing what I did, I would have hoped the Prius community would have seen this action 6 + years ago vs. waiting until I saw it for the first time on the highway late last summer. Can you imagine the fuel some Prius drivers could have saved if they would have known all about this stuff years ago?

___Good Luck

___Wayne

At this point I can propose a fairly effective "super flatlands
technique":
_ park engine RPM at 1800
_ hold the steering wheel
_ wait.
Cruise control can help with this a little but it gets a bit
too aggressive on those little overpass rises. But for the most
part minor adjustments down to, say, 1700 where the load starts
to fall off up to 2000 or thereabouts will still keep overall
MPG fairly good. The constancy of load can also lead to MFDs
that look like this:
http://techno-fandom.org/~hobbit/cars/flatmfd.jpg
Through the blur it's saying 58.2 over 300 miles, if I remember
right. I kept thinking it should have pushed a little higher
as I headed down into warmer weather, but I was probably still
on a tank of winter blend [what do they have in Georgia, where
I think I tanked up?]. Not too far off the summer ballpark of
low to mid sixties for interstate travel, though.
.
_H*

I have some new data to update my experience with SHM. Yesterday, I drove 155 miles from my house to Wayne's so we could go to the meeting in Oak Creek, WI. I used the IGN-14/TPS-18 method and the RPM's seemed to hang out from 1200-1250. The temps were in the low 30's. The speed range I used was a minimum of 45 mph and I would go back up to 50 mph and I would also allow the speed to go up to whatever it wanted to on the larger downhills. The results: 70.2 mpg:woot: Wayne drove from his house to Oak Creek, WI for the MIHG meeting which was 38.5 miles away and used the same technique of IGN-14/TPS-18/rpm's from 1200-1250. He had slushy roads for the first ~20 miles or so and was only able to get ~65 mpg. After the slush cleared, things went much better and he recovered to 70.2 by the end of the trip. It seems that my car didn't get the memo about rpm's below 1700 not being efficient.:p

That is just insane! Quite the numbers, guy! :thumbs_up: :D

An observation after a few hundred miles of driving on cruise control:

The most frequent shm place the computer chose was ign 15/tps 17 when falling down the back sides of hills.

This is a value I hadn't tried to hold before, it seems to be between 14/18 and 14/17, like a half pedal click between.

I did notice that ife jumped up slightly from both 14/18 and 14/17 and the car seemed like it released slightly when there.

I most likely have the car(and my foot) trained to sit in 14/18 and 14/17 so perhaps it will take time to adjust to trying to find and hold that spot.

Also, I noticed a couple of things happening at 47 mph. Sometimes when holding shm and declerating, the car will go into WS at 47 without asking for it. Also, the super-shm mode (tps 16, ign14-16) can be gotten into easily there. Has anyone else notice things like this around 47 mph?

I was able to try this on Saturday, when temps were in the high 30s and there was fog everywhere (it gave me a good excuse not to drive fast). I ended up doing more of my "Dash-and-Coast" technique between 45 and 55 MPH on US-151, with IGN-21 for Dashing (~30 MPG) and IGN-14 for coasting (anywhere from 80 MPG to 150 MPG). I was trying to hold speed with IGN-14, but it just wouldn't happen except on two slightly downhill parts, so I couldn't do proper SHM (I imagine it's due to the weather).

All in all, I ended up with 57.5 MPG over 118 miles, and the trip didn't take much longer than usual. Go me.

I was able to try this on Saturday, when temps were in the high 30s and there was fog everywhere (it gave me a good excuse not to drive fast). I ended up doing more of my "Dash-and-Coast" technique between 45 and 55 MPH on US-151, with IGN-21 for Dashing (~30 MPG) and IGN-14 for coasting (anywhere from 80 MPG to 150 MPG). I was trying to hold speed with IGN-14, but it just wouldn't happen except on two slightly downhill parts, so I couldn't do proper SHM (I imagine it's due to the weather).

All in all, I ended up with 57.5 MPG over 118 miles, and the trip didn't take much longer than usual. Go me.

That's about what I'm seeing. Unlike some people who can hold SHM in a snowstorm (not mentioning any names :p), at least in these temps (20s and 30s) with mostly clear roads, I can hold speed for some time at 15/20 or 15/21, but not 14/18. 15/21 is good for 70-75 instantaneous at 50MPH.

My highway segments recently:

58.6 / 300.1 miles / 27 to 37F / light rain, turned to snow and a few inches of accumulation by the time I reached the MNHG meet. I took highway 12, then 94/694 around the north side of the twin cities. Overall average speed including going through towns and hitting traffic of 44MPH.

59.0 / 62.0 miles / 19F / driving through accumulated snow, home from the MNHG meet. Gas stop in the middle. Slower due to less cleared roads. Average speed 40MPH.

45.5 / 32.6 miles / 16F
51.6 / 33.4 miles / 14F, a round trip stupidly driving through blowing snow and near-whiteout conditions. :( Average speed 36MPH.

60.3 / 266.5 miles / 33 to 37F - 60, barely. But I'll take it. :D Overall average speed 46MPH. A decent chunk of interstate there too.

Nice work Jerad!

As far as what I was doing, I think I found a sweet spot keying in at 1200-1300 RPM (1248 and 1280 were a good spots). I was getting anywhere between 80 and 150 MPG instantaneous (depending on terrian) and was only losing 1 MPH every ~3 seconds on flat terrain, with accelerating back up to speed I got 25 MPG instantaneous and gained about 1 MPH every second, which roughly figures out to be about 65-70 MPG (not bad in this weather). My trip was worse than that due to suboptimal terrain, though.

I really keyed in on this on the way back and got 55 MPG on the return trip (compared to 57.5 on the go-there trip).

Note that this RPM range tends to switch between IGN 14 and IGN 15 in this weather).

I'm gonna resurrect this thread, because I've got some new input
for it. I finally figured out why ignition gets retarded in
those low-RPM regions, and it hit me while I was studying a bunch
of stuff about *airplane* engines.
.
Piston-engine pilots generally have control of throttle and
mixture. The amount of fuel metered in does rise and fall with
throttle setting, but there's an additional knob to bias it fairly
heavily around either side of 14.7:1 and most of the time they
run way richer than that. Stoichiometric burn happens to mostly
coincide with the peak exhaust gas temperature, which is one of
the things they monitor so they're always talking about "rich
of peak" or "lean of peak". Besides that, many planes have a
"prop" control which is also referred to as "RPM" -- since varying
the pitch of the propeller tries to make it take a bigger or
smaller "bite" out of the air, it's the closest approximation
they have to a variable-ratio transmission -- i.e. something
that affects the balance of engine RPM vs. airspeed.
.
The kicker? They have NO control over ignition timing. It's
hard-set to somewhere around 20 deg BTDC, which for the normal
steady-state 2000+ RPM that these engines run is appropriate.
But there's a vicious trap lurking for these poor guys -- if they
let RPM drop but still place a high shaft load on the engine,
they're right into detonation land where damage starts happening.
There's no way to sense that and back off the spark timing, as
there is in almost every car made now.
.
The problem is that the rate at which a mixture burns doesn't
change that much, so at lower RPM you ignite well before TDC
but now the peak pressure pulse occurs *way* too early, while
the crank is still around high noon and it isn't going to move
the piston down. Increasing RPM gets the crank around faster
so the PPP occurs at the right place in rotation and now you get
plenty of torque. So pilots learn to strictly avoid low-RPM
scenarios at higher loads and dance delicately around the fact
that their engine control systems are 1930s state of the art
which will simply eat itself under the wrong conditions.
.
So that's why the Prius ECM backs the timing off so far when
RPM creeps down around 1200 -- it's probably mapped to do so,
and keep the peak pressure pulse in the right place. These
values are always trimmed using input from the knock sensor,
and so most car engines ride the delicate line between detonation
and torque falloff all the time. I bet you'd see this in any
other car, too, under the same high-torque/low-RPM scenario.
.
I was just stunned by learning this, but apparently the concept
of variable ignition timing and something other than the old
dual fixed magnetos is only now just barely starting to get
past the crusty FAA certification process. When you consider
that even your typical '57 chevy had a simple centrifugal system,
it just boggles the mind.
.
_H*

Hi Al:

___All is good except you are in the absolutely lowest torque point the engine can output while still maintaining some semblance of speed. When you see it for yourself, you are just going to shake your head and say WTF, the darn thing is barely above idle yet putting out enough HP to keep the car moving through the air at 50 mph while DWL. Maybe 20 HP at most?

___Your example insinuates the timing retardation at this low RPM is a bad thing to keep detonation from occurring but this is exactly what timing advance does. The same can be said from idle all the way up to red line if Toyota decided to tune the 1.5 that way. The Accord’s max FE bottom end comes in at or around 1,400, the Ranger around 1,300 and the MDX around 1,100 RPM’s. All with either a locked up TC (Accord and MDX Auto’s) or the Ranger in fifth. They do not perform anything like the Prius’ 1.5 at IG14 in a somewhat steady state DWL scenario however :D

___Let me know your thoughts …

___Good Luck

___Wayne

No, timing retardation isn't a *bad* thing, it's a *necessary*
thing to keep the pressure pulse pushing at the right time *and*
prevent bad things from happening. That implies that the low-end
grunt you seek is available, whereas it wouldn't be from how an
airplane engine is set up and controlled.
.
It just suddenly dawned on me that it's *why* we're seeing the
IGN decrease to 14 or 15 down there. If it didn't, you'd start
hearing rattle, rattle, rattle...
.
_H*

Hi Al:

___The bad part was the connotation and connection with an older airplane engine in the post above. We want timing retardation as that is what it is for maximizing efficiency while reducing or eliminating detonation so as to not destroy anything.

___What I am wondering more about is the HP requirements at that speed and how an ICE just above idle is not only providing enough power to propel the Prius at ~ 50 mph but holding onto such great FE in a somewhat heavy vehicle at the same time :)

___Good Luck

___Wayne

Hi Wayne and Al,

> ___What I am wondering more about is the HP requirements at that speed and how an ICE just above idle is not only providing enough power to propel the Prius at ~ 50 mph but holding onto such great FE in a somewhat heavy vehicle at the same time

Would the engine be running MG1 at that time, providing electricity for charging the battery and current for driving MG2 at the same time? Just a thought, given a partial understanding of Al's writeups on how the Prius works... Clearly, that power has to go somewhere. What does the mfd say?

cheers,
Bill

I have read that the Prius II requires 20 hp at 60 MPH. Based on published weight, Cd and frontal area, that would put it at around 13 hp at 50 mph.

Interesting stuff. I'll have to eyeball the FE of the Suburban relative to ign advance.It is a more primitive motor that the Prius, but it gets surprisingly good FE for a big 2 valve V-8 with its heritage firmly in the 60's.It wasn't my 1st choice(Pilot was) as a evac/home depot/second car, but I could have done worse.
On another related note-HAS ANYONE NOTICED THE NEW RECORD PRICE OF OIL-ALMOST $105/BARREL??
Thanks,
Charlie

On our cross-country drive, it seemed to me that combinations of the following make SHM almost impossible:
- Low temps - freezing and below. Once we hit warm So-Cal, it really woke up.
- Headwind
- Cargo weight - we had 3 in the car, plus some bags in the back.

Just for record, there are electronic ignition systems for aircraft, such as the LASAR system (http://www.aircraftspruce.com/catalog/eppages/lasarignsys.php). Many experimental/homebuilt aircraft, which do not have to use FAA-approved parts, have been using electronic ignitions (http://www.aircraftspruce.com/catalog/eppages/plasma2.php) for many years. FYI, my small two seater gets 35 mpg @ 180 mph. It has one magneto and one electronic ignition.

___Let me know your thoughts …

___Good Luck

___WayneMaybe I might give you a possible explanation. I've been discussing my Celica's MPG sweetspots on another forum. One of the things that came out of the discussion was, that under medium load conditions, the VVT goes into an intake/exhaust valve overlap internal EGR mode that reduces pumping losses. I know the Prius has a VVT ICE, so maybe this is what you are seeing?

Hi All:

___Larry and I just arrived back from the Green Vehicle Workshop in Milwaukee and I thought some might be interested in seeing SHM in the flesh. The SG-II reported 76.6 over 49.3 miles with the usual last bar pegged but I caught this one just as we were slowing down to leave the highay ...

http://www.cleanmpg.com/photos/data/2/76_6_mpg_segment_with_SHM.jpg

___Good Luck

___Wayne

What sort of speeds were you guys running for that segment?

Hi Tim:

___Between 45 and 55 mph while DWL and usually about 50. It was a beautiful sunny day with temps in the low 50’s and maybe a 5 mph side wind.

___Good Luck

___Wayne

Don't tell Wayne this but, while he was sleeping, I slowed down and did some 40-30 mph pulse and glides on I-94.:D Kidding. As Wayne said, the weather was nearly perfect and the Prius responded accordingly.

Wayne or Larry: What was the terrain like?

Jim, it was a mixture of flats along with some minor hills. I should also note that them mileage on the FCD was the cumulative total from my house to Wayne's, to the GVW, and back to Wayne's.

This is almost the same result we achieved in the Reenactment II near Bakersfield, CA. We averaged just under 50 MPH. The terrain was flat with small hills and valleys. Very little wind.

We pulsed at 23/19 TPS/IGN to 51 MPH. Then backed off to 18/14 TPS/IGN and it would slowly bleed off to 47 MPH. Then pulse again. The pulse yeilded 51 MPG at 23/19 TPS/IGN. The "glide" yielded 78 MPG at 18/14 TPS/IGN.

Note: This is a very tenuous condition. If there is the slightest prolonged uphill or any headwind it is difficult to hold the 18/14 TPS/IGN for the necssary time to get the 70 MPG figure.

Hi Jud:

___I have experienced SHM in (3) unloaded Prius’ for over 750 miles now and any stronger head or side wind, its toast just as everything else is. If only we were not fighting a 20 - 40 mph headwind from the Iowa border all the way to Salt Lake City, I believe we would have all seen more of the same :(

___The great part is the results are always repeatable around my locale in a well setup Prius-II. 100’ max elevation deltas over any 1 mile stretch and mostly 35’ overpasses to contend with here. Depending on the length of the hill, you have to drop out and maintain a minimum, than pick it back up on the other side of course. On that back side, you pull into the same IG14/TPS 18 and see well over 100 but you must transition into it quickly to make up for the climb after dropping out of DWL at 40 - 50 mpg or your previous 1 mile is wrecked.

___I have one more test to see whether it can be achieved in another Prius-II down in Texas next week. If Tarabell who may have all of 20 miles in a Prius-II can hold a Prius-II in this mode for tens of miles in an unfamiliar locale, I am going to bank it as a technique for everyone and whose use can be implemented in many locales. When the terrain is mostly flat with small undulating hills anyway ;)

___Good Luck

___Wayne

the super highway mode does work but i do it in another fashion... but it netted me 4 - 5 min bars of 2.5L/100km segments (92 mpg US) but i basically pulse towards a target and then WS behind him till he gets away from me pretty good, but then I start pulsing in a way where I can see my speed increase single digits (km/h) but at the same time using the target in front of me to eat up the areo load. So basically overwork the engine but let the guy in front of you absorb most of the damage! Rise and repeat my speed ranges would be 75 km/h to 95 km/h any

three digits hurt

can any of this be done without access to aftermarket hardware (like an SG-2)?
________
PAXIL WITHDRAW (http://www.classactionsettlements.org/lawsuit/paxil/)

It could be done without a Scanguage but it would be very difficult. You would have to back the throttle off until you saw the instantaneous jump into the high 70's or lower 80's. This would be from 50-55mph down as low as 45mph.

i find its easy to peg it at 94 mpg us (2.5L or just 1/4 of the bar for us Canadians being color filled) but then my speed begins to drop (or bleed as we like to call it) rapidly, so between high 70's and lower 80's is around 3.1 to 2.9 Liters / 100km so that is pretty hard to peg at since the screen updates pretty slowly without aftermarket hardware.

Is the IGN 14 just for the Prius, or can it work for my 07 2.0l Dodge Caliber SXT with CVT?

Is the IGN 14 just for the Prius, or can it work for my 07 2.0l Dodge Caliber SXT with CVT?If it works on the Dodge, its just luck. We suspect we hit an intentional efficient zone on slow decels.

can any of this be done without access to aftermarket hardware (like an SG-2)?Yes. Set to Castle display ("CONSUMPTION" screen). Get up to cruising speed (anywhere between 50 and 65 mph). Now Pulse up with the far right "bar" bouncing a little below or a little above 50. When your ready to glide, glide with the far right "bar" bouncing between 75 and 100.

That should be it for the most part

11011011

We suspect we hit an intentional efficient zone on slow decels.
Dan, I really suspect, as I said earlier, you are hitting the EGR mode of the VVT system. There is no EGR valve. The VVT purposely overlaps Intake & Exhaust valves on partial load to provide an EGR action and reduce pumping losses. Since the exhaust valves do not close until the intake valves have been open for a while, some of the exhaust gases are recirculated back into the cylinder at the same time as the new fuel / air mix is injected. As part of the fuel / air mix is replaced by exhaust gases, less fuel is needed. Because the exhaust gas is comprised of mostly non-combustible gas, such as CO2, the engine runs properly at the leaner fuel / air mixture without failing to combust.

I see similiar rises in MPG backing off TPS by one or two from a cruising speed on my 2ZZ-GE. I haven't watched IGN when I do it, though. So, I can't nail it to a specific IGN reading. Presumably, if you have a VVT engine, you can find similar results.

Hi 2way:

___I have never seen anything like SHM in the Corolla and I doubt we ever will :( The one item that is different about the SHM technique is the 1,208 – 1,248 RPM the Prius is turning over at 50 + mph. It would take an extremely tall CVT and nothing can come close where the Corolla’s or Yaris’ Auto’s or Sticks are concerned.

___Good Luck

___Wayne

So am I correct that the TPS is the throttle position in 0-100 percent? The 18 number is %18?

Hi Jay:

___Funny that I just got done driving a Prius for over 1,700 miles and I do not know the TPS range for one :rolleyes: Go out to your Prius with it booted but not in the ready state and look at the TPS output on your SG-II. It is probably around 14 the bottom and maybe 30 on the top? A Fuel cut setting at 15 leads me to that conclusion? The goofy thing is flooring it does not give a WOT output if you were force charging as I was in that condition 4 or 5 times before the launch to NY City. I suppose if you boot it into a non-ready state and put your foot to the floor the high end might be revealed but I would simply be guessing at best.

___Anyway, 18 via TPS is a bit more than 18% but the top of the range is much less than 100.

___Good Luck

___Wayne

So what would I be looking for on my can-view? I dont have a SGII. I can get IGN14 on the can-view but what do I look at for the TPS?

Hi Jay:

___Sorry but I cannot help you with that one? Does CAN-View display TPS? The next time I am in a Prius, I will find out the bottom and range but right now, the best bet would come form just about anybody else with a Prius in their drive and an SG-II attached :(

___Good Luck

___Wayne

Dan, I really suspect, as I said earlier, you are hitting the EGR mode of the VVT system.Very interesting. One thing I always found curious is how you actually have to chase and coax the car into that IGN14 groove. Sometimes it wants to stick at IGN16 even at very low RPM. I find sometimes I have to do mico-feathering of the throttle to get everything to fall into place.

Any thought on a gauge that would give this away?

EDIT: Wikipedia mentions EGR specifically implemented in Atkinson Cycle engines - http://en.wikipedia.org/wiki/Exhaust_gas_recirculation

11011011

for those without extra instrumentation i notice at speeds of 45-55 mph, when i try to peg high 70's low 80 mpg (2.9 to 3.3L/100km) i notice the MFD arrows keep having a personallity crisis! Trying to decide between putting power into the battery and then giving the juice away to mg2! Is that the SWM talking?

Well it does not really matter because I have been watching for IGN14 and MPG range between 65-75 will little to no drop in speed. This does very well for me and my short commute.

Wayne I would live to see what you could get on my 12 mile commute to work just to see if you could do any better than me. :) I know you could unless of course I'm doing the same things you would.

Since I'm able to capture data from my can-view now I will have to get a terrain map and plot out what I'm doing just to see if anything can be improved.

hm my speed still drops, but where i live having flats is a novolty... maybe i'll just stick with wrap stealh* pulse and glide.

Hi 2way:

___I have never seen anything like SHM in the Corolla and I doubt we ever will :( The one item that is different about the SHM technique is the 1,208 – 1,248 RPM the Prius is turning over at 50 + mph. It would take an extremely tall CVT and nothing can come close where the Corolla’s or Yaris’ Auto’s or Sticks are concerned.

___Good Luck

___WayneI still think you're seeing a function of the VVT valve overlap. The RPM will be unique to the vehicle, gearing, & VVTi mapping. Almost all your descriptions regarding timing relates to your ICE and the VVT valve overlap. On the flats, I can do the same thing.... except I haven't been watching IGN. Just doing it by TPS and iFCD. I can get up into the 70mpg range dropping TPS by 1-2 pts below a steady state cruise. While you may not see your specific "SHM" technique, I'm fairly positive that what you are seeing is the VVT action on the valve overlap..... allowing EGR and/or the reduction of intake manifold vacuum (reducing intake stroke downward piston resistance). However, w/a CVT, it could be a combination of both the CVT & VVT. I guess I'll have to start monitoring IGN.. 'cept my timing is pretty advanced w/a high comp engine & having to run Premium.

If you're seeing something in a particular RPM vs. a particular timing... you're probably looking at a resonance or torque dip. I know that I've identified two RPM mpg sweetspots on the 2ZZ-GE and those appear to correspond to torque dips in all the dynos I've seen for a 2ZZ. I don't think I've seen a dyno on the ICE in a Prius or a Yaris.

But, you're right... a 'rolla or Yaris should certainly be able to demonstrate this.... but, w/different values.

BTW, OUTSTANDING job on the CHI->NYC trip!

EDIT: Any thought on a gauge that would give this away?Darn good question. MAP, MAF maybe.... but there are too many other variables. Best candidate I can think of is maybe the Camshaft Position Sensor? Although, IGN should be the reaction to the CPS.

for those without extra instrumentation i notice at speeds of 45-55 mph, when i try to peg high 70's low 80 mpg (2.9 to 3.3L/100km) i notice the MFD arrows keep having a personallity crisis! Trying to decide between putting power into the battery and then giving the juice away to mg2! Is that the SWM talking?Yes, I noticed that too. My speculation was that the control software was doing it's bit to try to stick the engine at that state. I've noticed once it sticks you can play with the throttle (slightly) without falling off.

11011011

VVT-i allows the engine control system to independently adjust intake
valve timing. The 1NZ-FXE uses this ability to move between conventional valve timing and Atkinson cycle valve timing, varying the effective displacement of the engine.

In an Atkinson cycle engine, the intake valve is held open well into the compression stroke. While the valve is open, some of the cylinder volume is forced back into the intake manifold. This creates an effective reduction in engine displacement. By using the VVT-i system to continuously adjust intake valve timing between Atkinson cycle valve timing and conventional valve timing, the engine can maximize fuel efficiency whenever possible while still producing maximum power when required.

The maximum retard closing timing of the intake valve by the VVT-i system has been decreased from 115 degrees ABDC (After Bottom-Dead-Center) in the ’01-’03 Prius to
105 degrees ABDC in the ’04 & later Prius.

You'll pardon me, as I educate myself in things Prius. Wayne may have been more correct than I originally thought.... and it may have more to do with the VVT in the Atkinson cycle and a displacement optimization. In which case, you would not see this "SHM" in a 'rolla, Yaris, or my 2ZZ-GE. TNX, Dan.

But, you're right... a 'rolla or Yaris should certainly be able to demonstrate this.... but, w/different values.


Bailout showed me this in his Yaris, I believe it was a tps value = 21, ife jumped up 7 or 8 mpg switching from 22 to 21.

Hi Sup'd:

___Hang Time in many other vehicles is not the same thing as SHM in a Prius. The Prius' extremely low RPM that it runs at under SHM is something that I cannot explain but it works in the almost 3,000 # mid-size.

___I persionally cannot wait to see if it is avaible in the TCH with its less agressive atkinsonized 2.4L. Wouldn't that be a hoot. 55 mph and 55 + mpg from that beast if it is so?

___Good Luck

___Wayne

So what would I be looking for on my can-view? I dont have a SGII. I can get IGN14 on the can-view but what do I look at for the TPS?
Jay, CV doesn't have an equivalent to the ScanGauge TPS reading. TPS is for the vehicle throttle beneath the hood. CV displays a "throttle" position but, as you presumably know, it's for the go-pedal, measured on a 0-100% scale. It would be more accurate to call it "accelerator pedal" position.

The discussion of EGR with the Atkinson cycle engine interests me. If I understand correctly when the exhaust gas recirculates ... _____ (fill in the blank)

...the injection system doesn't squirt as much gas in the chamber to hit it's 14.7:1 air:fuel mixture for stoichiometric combustion.
...the system runs a bit richer than normal, instead of 14.7:1 it's more like 12:1 air:fuel mixture, which results in more power with each power-stroke.


So the question this leads me too, is how can you quantify what is happening? I trust the OEM gauge (FCD) so if it says I'm at 82 MPG on an IGN14 glide, I believe it. But would SGII show correct figures? SGII uses (I think) manifold pressure, and then back-solves assuming (I think) 14.7:1 mixture and the engine displacement set in it's memory. So if the answer to the fill-in-the-blank is #1, how would SGII know the mixture had changed?

Basically I want to start testing for EGR in other cars, and I'd like to find the smoking gun in the Prius SHM mystery. There are other gauges on the SGII I could key off of, but don't really know what to look for. Here are two docs that list what gauges are available:

http://www.scangauge.com/support/pdfs/SGMan5_0.pdf
http://www.scangauge.com/support/pdfs/XGAUGE.pdf

Any thoughts?

11011011

Can we work out a chart of what engine values are in shm and not and the ranking order?

IGN 15/TPS 19 at rpm 1344 is the highest rpm level where the shm effect works for me.

I've seen RPM 1280 ign 14 tps = 20 values, which has lower ife than 15/19 at the same speed.

I'm guessing that once you hit tps = 20 that you're out of it.

14-16/16 (I don't notice a difference in ife for any ign associated with tps = 16)
14/17
15/17
14/18
15/18
14/19
15/19
-------
14/20
15/20

Is the pedal position order I've noticed.

The discussion of EGR with the Atkinson cycle engine interests me. If I understand correctly when the exhaust gas recirculates ... _____ (fill in the blank)

...the injection system doesn't squirt as much gas in the chamber to hit it's 14.7:1 air:fuel mixture for stoichiometric combustion.
...the system runs a bit richer than normal, instead of 14.7:1 it's more like 12:1 air:fuel mixture, which results in more power with each power-stroke.


So the question this leads me too, is how can you quantify what is happening? I trust the OEM gauge (FCD) so if it says I'm at 82 MPG on an IGN14 glide, I believe it. But would SGII show correct figures? SGII uses (I think) manifold pressure, and then back-solves assuming (I think) 14.7:1 mixture and the engine displacement set in it's memory. So if the answer to the fill-in-the-blank is #1, how would SGII know the mixture had changed?

Basically I want to start testing for EGR in other cars, and I'd like to find the smoking gun in the Prius SHM mystery. There are other gauges on the SGII I could key off of, but don't really know what to look for. Here are two docs that list what gauges are available:

http://www.scangauge.com/support/pdfs/SGMan5_0.pdf
http://www.scangauge.com/support/pdfs/XGAUGE.pdf

Any thoughts?

11011011

i thought i swear the prius doesn't have a EGR system due to the easy going nature of the engine itself, I don't think its combustible temperatures will reach to a point where NOx formation is an issue, unless the engine runs very lean from time to time... As I understand from school EGR is used for emission controls and not every car has them because variable valve timing pretty much took over what EGR used to do.

What is IGN? Is the the ignition advance before TDC?

Does a smaller +ve value of IGN correspond to a spark ignition timed to occur later in the compression stroke? If so, does this mean that the intake valve timing is retarded further to allow more excess air to return to the intake manifold? That would mean maintaining stoichiometric combustion for very small quantities of fuel with very little or no EGR required. This means lower compression losses while maintaining a long expansion stroke. Just thinking aloud...

Maybe I threw this into the wrong thread last night. Do y'all
realize just how *closed* the throttle in the Prius really is
in the neighborhood of 20%? Take a look at this set of pics (http://techno-fandom.org/~hobbit/cars/tb/tps/)
for a bit of an eye opener.
.
I'm also staring at my old what-I-thought-was-VVT-change chart
[referenced therein] again, wondering if there are some hidden
sweet spots in there. I think it's time to go collect some
more data and try a more in-depth analysis.
.
_H*

Hi All,

Just a comment about ignition timing and RPM. Originally cars had a lever on the steering wheel to set iginition timing, which had to be advance as RPM came up. Then centrifugal advance was invented. It was a set of springs and weights down in the distributor which pivoted the distributor rotor. Now the computer looks up the time to ignite the fuel from a map of a variety of variables and inputs from a crank sensor.

The whole reason for this is gasoline takes time to burn. Its a chemical reaction, and takes the same time, no matter the engine RPM. But the time the piston takes to come up varies with RPM. So the ignition has to be set further and further before top dead center to get the peak pressure sufficiently close to the TDC, but after TDC.

Ignite the mixture too soon and the piston will retard the crank momentum. Too late and the pressure peak will not be as high because all the gas will not be reacted near TDC. There is a balance before the pressure developed before TDC, and the peak in pressure which is set to happen after, but near TDC.

Now I am sure there are some more detailed timing modifications for various temperatures, engine warmup, and load conditions. But its all biased based on RPM. The faster the RPM the earlier the ignition, or the higher the IGN value.

Maybe we should be looking for a offset from RPM bias IGN value ?

What a great explanation. It helped me understand this better. Thanks donee.

The discussion of EGR with the Atkinson cycle engine interests me. If I understand correctly when the exhaust gas recirculates ... _____ (fill in the blank)

...the injection system doesn't squirt as much gas in the chamber to hit it's 14.7:1 air:fuel mixture for stoichiometric combustion.
...the system runs a bit richer than normal, instead of 14.7:1 it's more like 12:1 air:fuel mixture, which results in more power with each power-stroke.


So the question this leads me too, is how can you quantify what is happening? I trust the OEM gauge (FCD) so if it says I'm at 82 MPG on an IGN14 glide, I believe it. But would SGII show correct figures? SGII uses (I think) manifold pressure, and then back-solves assuming (I think) 14.7:1 mixture and the engine displacement set in it's memory. So if the answer to the fill-in-the-blank is #1, how would SGII know the mixture had changed?

Basically I want to start testing for EGR in other cars, and I'd like to find the smoking gun in the Prius SHM mystery. There are other gauges on the SGII I could key off of, but don't really know what to look for.
Any thoughts?

11011011Dan, from my earlier post, my thoughts are more that it is a function of the Atkinson displacement change than the EGR function. The VVT's EGR function explains the 'rolla, Yaris, Celica change w/a slightly lower TPS. But, they aren't Atkinson. LOD & MAF change w/the EGR. My guess is that in such a low RPM range, as Wayne describes, you are in the Atkinson cycle and it is related to that. Which, from my original supposition, is still related to the VVT. Just a different function of it. More like an IGR function. FEH/CamryHB owners might find something similar? BTW, HPR might be an interesting one to watch.

Hobbit definitely might have more knowledge about all this.

Dan, you might find this EGR info interesting:
http://www.autospeed.com/A_110577/hDg34uLtp_1/cms/article.html
http://www.autospeed.com/A_110555/hDg34uLtp_1/cms/article.html
http://www.autospeed.com/cms/A_110581/article.html
There's even a possible +3% mod for Insight owners.

However, I now think (as above) that the Prius "SHM" is quite possibly related to the Atkinson IGR of the Prius. How goes it, Sir Hobbit?

Cool articles. I was thinking earlier that the way the Prius does the Atkinson cycle sounds more like a control unit hack than than a hard coded mechanical implementation. If that is the case, then is it possible that the Prius can pick between Otto cycle and Atkinson cycle simply depending on engine load conditions.

I'm beginning to wonder if the jump in MPG from IGN 16 to IGN 14 might be the engine switching from Otto cycle to Atkinson cycle. Definitely something there though.

11011011

I'm beginning to wonder if the jump in MPG from IGN 16 to IGN 14 might be the engine switching from Otto cycle to Atkinson cycle. I would think that in such a low RPM it would be fully in the Atkinson cycle. Given the tie to IGN, it certainly seems likely to be related to valve overlap/pumping losses. Whether it be Atkinson<->Otto, EGR, IGR, or some other mystery.

219/00DB????

Dan, the Otto/Atkinson changeover is an interesting point. As I understand it, the 1NZ-FXE does vary between Otto on high load and Atkinson on low load. Being Prius illiterate, what are the electric motors doing in SHM? Could this be a scenario where the electrics pretty much disengage and your running largely on the Atkinson cycle of the ICE? What is manifold vacuum doing in SHM, Hobbit?

There is no explicit switch between "otto" and "atkinson", and
EGR is done internally by valve overlap. See my valve timing (http://techno-fandom.org/~hobbit/cars/vvt/)
writeup for a bit of study into this.
.
I must admit I haven't studied SHM as originally described all
that much, but recently I've been playing with some low-RPM
vacuum observations that may be related. These are times when
I can slowly drop RPM from maybe 1600 down toward 1300 or so
and see a slight *dip* in vacuum rather than the expected rise,
implying a slight increase in throttle opening, and being able
to maintain mid forties / low fifties speeds at reasonably high
MPG. The situation collapses around 54 mph. I have yet to really
go out and collect good data on this, as it's not easy to find long
straight and *flat* stretches of mid-speed road around where I
live. The recent curiosity was sparked during our run down in
the flatlands of NJ two weekends ago, in fact.
.
_H*

Yeah, LONG flat stretches are pretty rare around here;) Could the *dip* also indicate the Atkinson cycle spitting stuff back into the intake plenum?

After talking to Hobbit at WFEC I started looking closely at TPS. Sure enough, IGN=14 & TPS=17 is A LOT better than IGN=14 & TPS=18. So next time your on the highway and your SoC stablizes, try a few glides at TPS18, then try a few glides at TPS17.

11011011

After talking to Hobbit at WFEC I started looking closely at TPS. Sure enough, IGN=14 & TPS=17 is A LOT better than IGN=14 & TPS=18. So next time your on the highway and your SoC stablizes, try a few glides at TPS18, then try a few glides at TPS17.

11011011

I've noticed that also, but the TPS 18 will hold the glide significantly longer.

I've noticed that also, but the TPS 18 will hold the glide significantly longer.Agreed. Don't know if the trade off would show better results (over the long term)... ie 10% more FE, but 10% less time in SHM may end up canceling each other out.

11011011

Hi All:

___Glides nothing. IG14/TPS18 can be held as long as there is no impediment. Wind, long uphill slope etc. 17 in a slower speed but that is a NICE-On like action in my experience.

___Good Luck

___Wayne

It is interesting to watch what the computer does in cruise control, it likes 15/17 for downhills. I would suggested driving in cc for a few hundred miles sometime to watch the RPM/IGN/TPS settings it uses at different times. I only use positions that the computer uses and have seen improvements.

Some notes:
When asking for WS and getting denied, it goes almost 100% into 15 or 14/17.
With a high state of charge, getting into for 14/18 a few seconds later the car goes into WS without asking for it and no pedal movement.

I don't have an xgauge to get soc, but I'm thinking at or below the WS deny threshold should always use shm, above the ask for shm gives you WS without asking threshold always use WS. In between based on speed/terrain.

OK... So the new XGauges Rock for SHM.

Just hold gps at about 14.0% and your there. Then if you see your rpm drop below 1200, just bump gps up to 14.5%. Your rpm will drop as your speed drops so you'll need to start your SHM glide at gps of 14.0 % and over the glide you'll slowly work up to gps of 15.0 - 15.5 %. Having the gps gauge and the real-time rpm makes this like shooting fish in a barrel.

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PS: red indicates the new gauges, not the old ones.... OK... Dan will shut up now about XGauge.

Just added alot of these gauges. what purpose does the horsepower gauge serve in hypermiling?
Any way to get a torque gauge?
Oh and you rock btw. :)
Thanks
Ryan

Nice work, Dan.

OK... So the new XGauges Rock for SHM.

Just hold gps at about 14.0% and your there. Then if you see your rpm drop below 1200, just bump gps up to 14.5%. Your rpm will drop as your speed drops so you'll need to start your SHM glide at gps of 14.0 % and over the glide you'll slowly work up to gps of 15.0 - 15.5 %. Having the gps gauge and the real-time rpm makes this like shooting fish in a barrel.

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PS: red indicates the new gauges, not the old ones.... OK... Dan will shut up now about XGauge.

Dan, please don't shut up about the XGauge. Ever.:D You are putting up some valuable info.:) I tried the gps(codes from the spreadsheet) and couldn't seem to make it work.:confused: I may have opportunity to make use of gps on Saturday depending on how work goes.;)

Just added alot of these gauges.If you have any trouble, please post the SG FW rev (note any astricks "*" in the string). Also note whether the gage was born with that FW or upgraded... Ohh and of course, Model Year of your Prius. These aren't working on all cars, so there is some variability I haven't isolated.what purpose does the horsepower gauge serve in hypermiling?None... but I thought it would be cool to catalog what hp is being used in SHM.Any way to get a torque gauge?Yeah, Bob (bwilson4web@greenhybrid) has it figured out here:
http://www.greenhybrid.com/discuss/f10/measuring-prius-thrust-mg1-mg2-torque-18220/

Problem is net torque requires math to be done on both MG1 torque and MG2 torque. Ron could add this in one of his FW revs, but right now you can only perform math on the data you get. No way to multiply or add two gauges togeather without ScanGauge.com pitching in with an assist. I may ask Bob for the MG1/2 torque PIDs, mode, and ECU they reside on, but it may be frowned upon. He's using a Graham Scanner currently, and I think their EULA prevents anyone from publishing the PIDs they decode. But... if anyone knows the PID/mode/ECU for the MG1 and MG2 torque and/or RPM, I'll be happy to code up the gauge.Nice work, Dan.Ditto.

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This definately works in the TCH (Camry) but with some modifications. First of all, in the Prius, I do a fairly aggressive pulse (1600 RPM), In the Camry I don't (1280 RPM pulse). It seems like in the Camry, you can get a type of reduced SHM while still accelerating from 50 to 55 mph. IGN reads 20 and RPM about 1280. So I pulse at IGN 20 and Glide at IGN 18.

Now the interesting part about the Camry is that it seems very LOD dependent. I wasn't monitoring LOD, but noticed I couldn't hit IGN 18 with 60+ MPG on an incline. It either had to be flat or downhill. Once I set SHM I could take an incline without loosing it, but you can't set it on an incline.

Next thing that was odd, is that IGN 18 shows up all over the place on the Camry. SHM only shows up when IGN < 19 and RPM < 1200. This is the set point. Once SHM is set, you can bump RPM up just over 1200 without loosing it. Another odd thing is that SHM shows up in other spots as well if LOD drops sufficiently. I would see the MPG dial bounce from 40 to 60 and back to 40 while just ticking along in what I thought was a steady state test. But if you watch terrain closely and dial in "gps" on scangauge, you can find it very consistantly. I suspect much of this will translate to the Prius as well, but since I don't have my Prius I can't really verify.

OK... SHM update on the highway.... It is certainly squirly. Anyway... the numbers are Pulse at RPM/IGN/TPS of 1280/20/22 and glide at 1120/18/18. This yielded highway numbers of 50.3, 51.0 and 53.2. It's very hard though... You can't be on an incline for a glide... have to be downhill. Grade of the road makes a big difference. Also, if you ever pop the RPM above 1350, you have to go back to a low 1100 for about 5 seconds for things to reset. GPS (gas pedal gauge) is really required.

Pulse at GPS of 25.0, to enter a glide drop GPS to 10.0, once IGN drops below 19, you can slowly step GPS (in 0.5 increments) till your at TPS of 18 or 19 and IGN still at 18. Highest GPS I've seen in a glide was 20.0. The MPG dial is a hoot in SHM... I've seen it bounce from 40 to 60 with no change in RPM at all... really wild. Definitely follows IGN though.

Running the numbers... 50 MPG on the highway in a TCH is the same feat as 70 MPG in a Prius on the highway.

Doesn't the Camry just use the Otto cycle? In which case, you'd just be seeing the EGR action.

Hi 2Way:

___I suspect the TCH has some atkinsonization even though it is not listed as such given its 2.4L outputs 147HP while the equivalent 2.4L in the non-hybrid outputs 158. I think of it as a mild atkinsonization although it could be something else? The 1.5L in the Yaris is worth 106 HP while the same 1.5L in the Prius after a little more aggressive atkinsonization is worth only 76.

___Good Luck

___Wayne

Doesn't the Camry just use the Otto cycle? In which case, you'd just be seeing the EGR action.

___I suspect the TCH has some atkinsonization even though it is not listed as such given its 2.4L outputs 147HP while the equivalent 2.4L in the non-hybrid outputs 158.

Wiki told me that it's Atkinson, and Wiki generally doesn't lie for more than a week or two.

Wikipedia: 2AZ-FXE Engine (http://en.wikipedia.org/wiki/Toyota_AZ_engine#2AZ-FXE)

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Ah yup... I hadn't looked it up. But, it makes sense that they would also do it (Atkinson cycle) with the Camry.

Anybody know what the optimal IGN range is for the 08 Nissan Altima Hybrid?

OK... So the new XGauges Rock for SHM.

Just hold gps at about 14.0% and your there. Then if you see your rpm drop below 1200, just bump gps up to 14.5%. Your rpm will drop as your speed drops so you'll need to start your SHM glide at gps of 14.0 % and over the glide you'll slowly work up to gps of 15.0 - 15.5 %. Having the gps gauge and the real-time rpm makes this like shooting fish in a barrel.

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PS: red indicates the new gauges, not the old ones.... OK... Dan will shut up now about XGauge.

Huh. Using the new "gps" (which rocks, btw) I've seen that gps = 18.0% corresponds perfectly with IGN14/TPS18. TPS doesn't line up with gps this well at any other point. But in my '05 18% is where it's at.

And BTA is a great explanation of "WTF why is my normal SHM only showing 65 instantaneous?" (notice those -8 charging amps?) or the opposite "sweet! I have 99.9 instantaneous pegged in highway driving!" (see those 6 amps coming off the battery?). I drove a lot of highway in the past few weeks and I'd see some crazy SoC seeking every few days... start at ~57, seek all the way up to 64.5, then reverse and DIScharge down to below 60, and finally stabilize around 62, and only THEN would SHM work "normally".

Huh. Using the new "gps" (which rocks, btw) I've seen that gps = 18.0% corresponds perfectly with IGN14/TPS18. TPS doesn't line up with gps this well at any other point. But in my '05 18% is where it's at.

And BTA is a great explanation of "WTF why is my normal SHM only showing 65 instantaneous?" (notice those -8 charging amps?) or the opposite "sweet! I have 99.9 instantaneous pegged in highway driving!" (see those 6 amps coming off the battery?). I drove a lot of highway in the past few weeks and I'd see some crazy SoC seeking every few days... start at ~57, seek all the way up to 64.5, then reverse and DIScharge down to below 60, and finally stabilize around 62, and only THEN would SHM work "normally".For the 75mpg segments I'd try to seek TPS of 17 by holding GPS at 16 while gliding down from 56 mph to some lower speed. After the SOC is around 61 percent, if you hold GPS at 16 for 7-10 seconds you will see TPS drop to 17 and MPG hit 90+. You will also feel a little boost in power output when TPS drops like a semi just put you in it's slipstream.

I started watching BTA in SHM and your right.. SHM puts BTA at darn near zero when you've got it cornered.

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I don't recall anyone posting about this but I will go ahead and post my new finding.

What I have found may not give you high MPG like the P&G TPS 18, IGN 14 but what I found would get good MPG without loosing too much speed and may keep the drivers behind you more happy.

What I found on my way home from the July 5th Cincinnati meet as well as going to and from Hybridfest was that a speed of about 60mph + or - 2mph and a TPS of 22 and IGN of 17 will let you keep your speed on a level road or very very slowly drop speed on a slight uphill and the MPG readout will be between 65mpg and 70mpg.

Some of you may want to play with that and report back on what you find.

I don't post a lot but am enjoying the heck out of reading this thread! I made a chart with the

IGN Avg Mph Avg Mpg

and the numbers I got from this thread including this last one form TheForce, and I am going to use them to test for myself the next couple days. I drive 33 miles one way to work mostly interstate but have found I can get away with 55 to 65mph at times if staying to the right. At night 2330hrs when I go home it is easy to do as slow as I want usually.

The combination of my Prius, SG2, and this forum is a real turn on guys!

Thanks!

I don't post a lot but am enjoying the heck out of reading this thread! I made a chart with the

IGN Avg Mph Avg Mpg

and the numbers I got from this thread including this last one form TheForce, and I am going to use them to test for myself the next couple days. I drive 33 miles one way to work mostly interstate but have found I can get away with 55 to 65mph at times if staying to the right. At night 2330hrs when I go home it is easy to do as slow as I want usually.

The combination of my Prius, SG2, and this forum is a real turn on guys!

Thanks!

Boy, would LOVE to get that chart for the Nissan Altima Hybrid! Anybody have one??? :)

Anyone know what the ideal IGN for the Yaris AT is? I find that around 22 TPS on a flat grade, I stay around 32-35 IGN. It's strange, as the IGN goes DOWN the more I apply the gas...

IGN going down with more throttle is the way most cars work. The toyota hybrids are unique in IGN going up with more throttle. As far as if the works in the Yaris or not I don't know. May be part of the Atkinson trimming or may be something else all together. It does serve as a good way to zero in a a throttle value though.

One suggestion that Mark made in the last hybrid meetup was that this may be an exhaust harmonic. All exhaust systems have harmonics as a byproduct of their design. When your off the harmonic there is back pressure in the exhaust and the engine has to work (a little) harder to overcome it. When your on the harmonic things go a bit easier.

I don't know if that is it, but the 7 second hold to get things really high makes me think there is some intent here in the design for this mode of operation.

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Found a fun new SHM game in the Prius.

Trying to fix the "bta" XGauge, I finally just gave up and decided to live with the scaling being off by a factor of 160. The result was kinda cool...

WARNING: the gauge is in the car, coding from memory....

bta
0x0033
0x0100823B0000
0x1410
0x000100010000

Now the only thing to really watch is the negative sign. When the bta number is negative your in regen, when it's absent your in assist.

So here's the game, bring up the FU'd bta gauge above and get up to around 40-50 mph.

Now ease off the gas (gps XGauge) until the negative sign twinkles. The idea is to get right on the border of the point where the engine can't decide whether to assist or regen. Once you find it the neg sign will start blinking madly. This turns out to also yield a real good FE steady state. The higher your SOC the higher your steady state speed.

I've noticed that bta twinkles when in SHM so I decided to see if twinkling bta was enough to get good FE... it's pretty close. Now full SHM doesn't really happen till your at a good high SOC, but this is a good way to get some of the SHM P&G benefits while your building up your SOC.

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damn and i wrote bta as battery voltage -_-; can you make sure its the right code since i don't want to challenge your disclaimer :P

Battery current bobbles an amp or two in either direction when
you're at 60% SOC and not making any specific demands, and doesn't
have a whole lot to do with how efficiently the engine is running.
You'd be much better off watching injector time (http://www.cleanmpg.com/forums/showthread.php?t=16129) and keeping it
in the fives.
.
_H*

Confirmed!

For the 75mpg segments I'd try to seek TPS of 17 by holding GPS at 16 while gliding down from 56 mph to some lower speed. After the SOC is around 61 percent, if you hold GPS at 16 for 7-10 seconds you will see TPS drop to 17 and MPG hit 90+. You will also feel a little boost in power output when TPS drops like a semi just put you in it's slipstream.

I started watching BTA in SHM and your right.. SHM puts BTA at darn near zero when you've got it cornered.The "boost" you feel in SHM after holding for 7-10 seconds is the release of forced regen into the battery. Using my bta gauge I see BTA drop from the +7 to +10 amps (regen) range to a -4 to +4 amp range. That 10amp regen is dragging the engine causing extra fuel burn and quicker decel. It releases after 7-10 seconds and the regen seems in equilibrium. It bounces back and forth. If you have the passive XGauge bta gauge, you will see it flicker from regen to assist to regen a dozen times a second. This is the sweet spot.

Hobbit was right earlier though. This mode is simply the efficient low band RPM in the prius. I'm not as convinced that there is some Atkinson magic here.

Found a fun new SHM game in the Prius.

Trying to fix the "bta" XGauge, I finally just gave up and decided to live with the scaling being off by a factor of 160. The result was kinda cool...

WARNING: the gauge is in the car, coding from memory....

bta
0x0033
0x0100823B0000
0x1410
0x000100010000

Now the only thing to really watch is the negative sign. When the bta number is negative your in regen, when it's absent your in assist.

So here's the game, bring up the FU'd bta gauge above and get up to around 40-50 mph.

Now ease off the gas (gps XGauge) until the negative sign twinkles. The idea is to get right on the border of the point where the engine can't decide whether to assist or regen. Once you find it the neg sign will start blinking madly. This turns out to also yield a real good FE steady state. The higher your SOC the higher your steady state speed.

I've noticed that bta twinkles when in SHM so I decided to see if twinkling bta was enough to get good FE... it's pretty close. Now full SHM doesn't really happen till your at a good high SOC, but this is a good way to get some of the SHM P&G benefits while your building up your SOC.Without going into SHM you can find a type of sliding scale here based on the passive-can bta XGauge, and the passive-can gps XGauge. Once you hit your top speed, slowly let off the gas (dropping gps by 1.0 at a time). Eventually, you will see bta drop below 1000 (6.3 amps). Soon after that you will see the "-" sign twinkle on/off a few dozen times per second. When this happens, hold throttle keeping your gps number constant. This is usually good for very long sustainable 70 mpg coasts. This spot seems to show up again at the right speed in the 90 mpg range.

Finally think I figured this thing out!

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That's pretty awesome, Dan! I'm amazed by what you've been able to discover about the Prius. :thumbs_up:

I can just see trying to explain to Joe Toothless how you need
to hold your twinkling beady-A and let the terrain be your
master. He might pick up on the "twinkie" part if he's on the
ball, but that's about it...
.
_H*

I would like to confirm Dan's observations relating to gps/IGN17. I had a long trip to Akron, OH and back several months ago so I had a lot of time for observation. Without having read Dan's previous posts about this series of conditions, I started noticing a pattern after a couple of hours: Get up to ~55mph and slowly let off gas until gps hit 16.5 or below, IGN hits 17, and mpg goes to 90+. The lower speed limit for this condition seems to be about 45mph. I also noticed that you can keep IGN17 if gps goes to 17. If gps goes above 17 for more than ~10 seconds, IGN will jump to 18 and mpg drops to the 70mpg range and you will have to start all over again.

Started a new Super Highway Mode Revisited thread where I think I have the mystery solved...A few years ago Wayne tipped me off to some really nice behavior on the Prius at low RPM. We've been able to replicated fairly regularly with the following recipe and SG gauges (TPS, IGN, SOC, RPM):

Do highspeed P&G with Warp Stealth until SOC is 61% or higher.
Ensure that block temp is over 165 degF (70 c).
Switch to CONSUMPTION on the MFD (castle display) to watch the instant MPG bar.
Get up to a speed of about 62-65 mph.
Now slowly ease off the gas pedal until you can hold a reading of 14 on IGN and 18 on TPS.
You should see your MPG bar at something between 75-85 MPG.
Hold this pedal position for 7 seconds and you should see TPS drop from 18 to 17.
Once TPS drops you should see the MPG bar jump to 85-95 mpg range.
Hold this "SHM" glide for a long as you can, then go back to step 4.


This much we know, and it is well established. The bit of mystery is "What exactly happens in 7 and 8, and why?"

Well the answer revealed itself...

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Inspired by the two threads going on about this, I hooked up
the Autoenginuity and went out for a bit of data-collection
this afternoon. First of all, here's my data -- *all* of it:
-> http://techno-fandom.org/~hobbit/cars/sweet/loafing.csv (http://techno-fandom.org/%7Ehobbit/cars/sweet/loafing.csv)
for anyone's statistical pleasure. I collected spark advance,
RPM, engine torque [which I believe is calculated by the hybrid
ECU from motor torque, but who knows], injector time, and speed.
The file has a label line at the top. I didn't include LOD
because I know that my non-upgraded ECU reports it bizarrely
and I can more or less see it via my vacuum gauge and/or the
torque figure. Then I went back and re-read both threads
in parallel with composing this just to make sure I had the
whole picture. What else to do on a nice sunny Labor Day
afternoon? I already got my labor in, smoothing down and
painting six big cinderblocks for use as tent weights.
.
....
.
_H*

Hello I just went through this great thread and registered (had been visiting as a guest from time to time for about a year). I haven't seen any analysis of the loafing.csv data in this thread. Is it done somewhere else? Thanks!

...

Another fun thing is to try IGN14 in the city. This is a 1300-1600 RPM pulse, but it moves around a lot so you gotta chase it. Point is, that I think IGN14 is what we've been chasing forever now. It explains the 1600 RPM efficiency I was seeing earlier and it explains the low RPM efficiency Wayne was seeing.

I consider IGN15 a less aggressive form of IGN14 and IGN13 a more aggressive form of IGN14. Wayne seems to be shooting for IGN13 a lot, I'm usually happy with IGN15 or below.

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It just so happened today that there was a truck in front and a commercial van behind, both going below the speed limit (30 ~ 40 MPH), and leaving a long enough interval in between for me to try out the IGN 14 pulse. What a chance in a lifetime! :D

It does seem like a chase game, especially my commute is not flat. Sometimes it would hold constant speed on an up slope at about 1200 RPM. When pulsing it could be 1300 or 1500 or 1200. In general it seems a gentler pulse than a "brisk" acceleration. When I hit it the sound of the engine does match the "low rumble" loaded sound.

Here are some difficulties I encounter and hope to get some advice from you experts:

Pressing accelerator down further causes higher RPM, but not necessarily higher IGN
Sometimes it seems got stuck at, say IGN 11, no matter what I do
Sometimes it jumps between 13 and 15Thanks!

Welcome to CleanMPG!

I had Dan personally walk me thru this with ScanGage II to make this easy. :)

Please realize that this thread is fairly old, and while much of it
likely still holds true, I would recommend reading a recent update (http://techno-fandom.org/~hobbit/cars/sweet/refl.html)
on my own studies.
.
_H*

Please realize that this thread is fairly old, and while much of it
likely still holds true, I would recommend reading a recent update (http://techno-fandom.org/%7Ehobbit/cars/sweet/refl.html)
on my own studies.
.
_H*

I came back to this thread exactly because of your recent update quoted above. ;)

I saw your reply in another thread http://www.cleanmpg.com/forums/showpost.php?p=271347&postcount=7 but there is still no definite numbers. It would be nice to have a set of MPG vs. MPH values for SHM and your high speed pulse and glide technique to compare with each other. So far this thread has some MPG vs. MPH data for the SHM but I haven't seen the same kind of data of your technique yet. Maybe it will take some time to collect them. I would be curious to know when available. Thanks!