Throttle control

[Skwyre7]

brick, keep us posted. I'll pay close attention to what I see on my SG going home this afternoon.

[JimboK]

Originally Posted by brick

One of two things is going on here. One is that our cars are really behaving differently. It is possible that the control algorithms were changed between 2005 and 2007 but it seems like they ought to have had this figured out for the initial release.

That thought occurred to me, especially after Skwyre7 reported results similar to mine in his 2005.

Originally Posted by brick

It is also possible that either my driving style or environment is inducing this behavior in a way that is not typical for you. I think that this is the most likely case given that you are talking about speeds up to 50mph that I essentially skip right over. It's either 25-40mph or 55-65mph for me. I also have a tendency to mimic a P&G routine on those roads. (It's also worth mentioning that our average FE is very close, so there can't be **that** much difference between what we're doing.)

I think from your description that our driving styles are similar. I too P&G whenever practical, and I try to avoid speeds in the 40-55 range due to their relative inefficiency. Last night's and this morning's drives were mostly on 2-lane rural roads, ideal for P&G if traffic allows. However, traffic was often behind me. If that's the case I minimize P&G or avoid it completely in the 45 or 55 zones. (I always try to balance FE and courtesy, and avoid provoking road rage.) But it's hard to get much faster on these roads. Unfortunately, some of them, even with 55 posted, aren't safe much above 45. Anyway, at lower speeds the LOD consistently stays below about 50 unless I'm accelerating.

Environment may be an issue. Presumably it's colder there than here.

Originally Posted by brick

The other possibility that one or both of our ScanGauges is lying to us. I doubt it but you never know. I might switch one of my readouts to MAP to see if those numbers match LOD the way I think they should.

I don't get a MAP reading, which led me to conclude it's not part of the Prius ODB stream. Do you get it?

The other parameter I've watched recently is throttle position (TPS). A reading in the range of 23-27 seems to align with the RPM sweet spot. It doesn't have the small but rapid fluctuations of RPM, so it may be easier to monitor. Haven't made up my mind for sure on that one yet.

[hobbit]

Wow, this ol' thread pops out of the closet. Well, that's cool
because I'm *still* working on the final report from my trip
southward, but I'm working a convention this weekend that I've
been prepping for and there's a lot of detail from the trip
I want to nail down and get in there. I'll hopefully have
all that up soon, and should probably fire a pointer into
here too.
.
No, it's not gonna have "the answer" either, but may give folks
a few different things to try.
.
_H*

[TheForce]

I just got back from a long trip and I applied the techniques described by hobbit.

The temperature was between 30-40F degrees.

I do have my grille bocked so it may have helped out a lot with these numbers.

My mom and dad were with me.

I also had about 50lbs of cargo.

Here are some of my results.

45-55mph
70mpg, 1400rpm, speed is steady or very slowly falling.
65mpg, 1500-1600rpm, Speed is steady or rising slowly.
55mpg, 1600-1700rpm and speed is slowly increasing.
35mpg, 1700-2200rpm speed in increasing pretty quickly.

55-65mph.
Just subtract about 5mpg from the above results.

It seems that the sweet spot is between 1400rpm and 2200rpm.

1400-1500rpm seem to keep your speed. 1600-2200 seem to accelerate the car at decent MPG numbers.

To get the good mileage you cant just floor it to your speed and back off. If you do this the Prius does kind of get stuck in a gas hog mode and makes it hard to get really good mileage at 1400rpm and maintain your speed. What I did was try to limit my acceleration from a stop to 2400rpm MAX. I would then go over the desired speed by a few MPH, completely back off of the accelerator and gently reapply until I reached about 1500-1700rpm then I started to back off until I hit the sweet 1400rpm area. This usually left me with in 1mph of my target speed.

I also was using the warpstealth method when going down hill on the interstate. I was surprised that I could gain speed in this mode when below 60mph. Anything over that I think the wind resistance was holding me back from gaining more speed.

The trip up the temps went from 40-30F and on the way back they were 30-40F. On the way up I tried this for about an hour and got tired and let cruse control take over. I averaged 52mpg. On the way back I used this technique all the way home and I pulled into the driveway with 55mpg on the tank so far. I think I may have averaged about 60+mpg coming back. This trip was about 95% highway.

I cant wait for summer temperatures.

[TheForce]

I would like to add that I did the same thing tonight on my way to bowling and had simular results. I kept the RPM between 1200 and 2200 the whole time and managed to average 55mpg over 60 miles with speeds as high as 65mph. The temperature was 37F degrees.

I had horse power on my screen this time ( at least I think it was HP ) and here is what I found.

At 55mph I could maintain that speed with about 12HP.

At 65mph I could maintain that speed with about 16HP.

Do these numbers sound right?

When the temperatures warm up I would like to take a video of my Can-View while driving so I can analyze it later. and also post it for everyone to see what this car can do.