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Hi all, this is my first post here, but I've been around greenhybrid for awhile and see many familar names here.

I drive a '05 Tacoma 2wd 2.7L manual, and I'm extremely pleased with the FE i've gotten over that last 1.5 years and 15,000 miles, with an average of 28.2mpg. The 2.7L is amazing. I have a scangauge and try to maximize my FE, my best tank has been 33.5mpg over 601 miles.

I haven't really gotten out on the open interstate so far but I'm heading out from Boulder CO to Vegas this Thursday. I'll be driving across CO, down through Utah all interstate to Vegas.

Any strategies?

I find I get good results with neutral coasts on downhill grades, but I'm expecting to need to use a lot of engine braking. I plan on being in the right hand lane along with the truckers within reason, and trying close and far drafting, though I'll probably be more on the far side, I hate not seeing what's up ahead.

If I had all the time in the world I'd cut down across CO on state roads to Durango, and below the grand canyon, but it's already going to be a lot of driving for a 5 day weekend.

Anyways, any thoughts would be appreciated.

Thanks

Steve

Probably the thing that would help the most is the most difficult in your situation. Drive slower. It is hard because everyone including myself want to get to our destination as quickly as possible. It has been tough to ween myself off speed. I use to do 90 in my geo metro when I drove from MA to DC. Now when I drive on the highways (I don't do much highway driving these days, but when I do) I try to go from about 50-60. Meaning I'll get up to 60mph and use just enough gas to decelerate slowly to 50 and then back up to 60. If you think that is too slow then pick a speed you feel comfortable with and slowly drop a few miles per hour until you reach the limit of slowness you are willing to drive. I also try to drive with load as much as possible.

Also make sure you tires are pumped up, preferably to max sidewall.

I also wonder if renting a Fuel efficient car for the trip will be cheaper than paying for gas. Just something to think about.

Probably the thing that would help the most is the most difficult in your situation. Drive slower. It is hard because everyone including myself want to get to our destination as quickly as possible. It has been tough to ween myself off speed. I use to do 90 in my geo metro when I drove from MA to DC. Now when I drive on the highways (I don't do much highway driving these days, but when I do) I try to go from about 50-60. Meaning I'll get up to 60mph and use just enough gas to decelerate slowly to 50 and then back up to 60. If you think that is too slow then pick a speed you feel comfortable with and slowly drop a few miles per hour until you reach the limit of slowness you are willing to drive. I also try to drive with load as much as possible.

Also make sure you tires are pumped up, preferably to max sidewall.

I also wonder if renting a Fuel efficient car for the trip will be cheaper than paying for gas. Just something to think about.


I have a fuel efficient truck already :) I'm expecting low 30s, this trip is mostly an excuse to get out and find out what she can do, while getting the wife to Vegas, which she's always wanted to do. She understands the meaning of nest egg.

I scheduled the trip around the 3 day "Mopars at the Strip" car show at the Las Vegas Motor Speedway. I'd drive my 70 Dodge Challenger convertible but @ 16mpg, 'nuff said.:cool:

60 to 50 to 60 probably won't work to well on uphill grades, but I'm thinking 5 below speed limit on uphill, cresting at 10 below speed limit and 15+ over speed limit on the way back down.:Banane49:

Secondary question, with my scangauge I show more fuel consumption with engine braking than in neutral, and I have gotten good corrolation with actual vs scangauge fuel use and think that I'm not getting any injector shutoff during engine braking, though I'm not positive.

It's possible that I'm just getting more benefit from the lack of engine braking while coasting in neutral on flat/inclined ground, which exceeds the benefit of injector shutoff with the added braking that I generally don't want. I don't think the scangauge really knows if there is injector shutoff (again not positive), because it never shows zero consumption.

I really don't know if I'm better off (comsumimg zero gas) while engine braking using the scangauge info.

With a lot of downhill I'd hate to be trying to maximize neutral if I'm actually getting injector shutoff. Can't find anything from Toyota.

My strategy would be maintaining speed limit or so on the downhills in gear and engine braking until I get near a bottom and then go to neutral for speed/momentum increase to help on the next climb, if I was getting injector shutoff.

Welcome!

Load driving (decreasing speed on the way up and increasing speed on the way down) works for the small hills in a traffic-free area, but for those big hills there isn't much you can do but pick a steady speed and ignore the ScanGauge until it's over.

The engine braking question is a very good one. The ScanGauge doesn't measure injector timing directly. Instead, it appears that it's using engine displacement, RPM, and vacuum to infer fuel consumption by way of air flow rate. (This is why 5MT Insight drivers see such bizarre numbers when the car is running lean...it just has no idea what's going on.) My strategy in the Accord was to start coasting as early as possible in neutral and take advantage of the fuel injector cut-off only when I actually needed to stop or slow down substantially. It may be different in the Tacoma, but I very rarely found a hill where I could maintain speed on the way down with the car in gear and my foot off the gas.

Speed is bound to be the most important factor on the open road. Keep that reasonable and you'll do well. Have fun in Vegas!

Welcome, Steve! I think I've chatted with you on GH, haven't I?

I'll defer to the masters here for advice on how to squeeze maximum mileage out of a conventional vehicle. I live in my own little Prius-world with its unique hypermiling capabilities, and I never so much as thought about fuel-efficient driving before I bought it. I think Tom and I were going door-to-door once somewhere in MD. :)

You can use the Scangauge's Open/Closed Loop gauge to see if it's in fuel cutoff mode. It should go open loop on the downhills, and then back closed when you actually use some power. It would be nice if it handled cutoff, but this is a rough way to see it anyway.

... for those big hills there isn't much you can do but pick a steady speed and ignore the ScanGauge until it's over.

QFT

I climb a summit 4,500 feet higher than my starting elevation every day and then climb 2,500 feet on the back side on the way home. I have tried every trick I can think of (including close-in drafting, which I posted about the other day) to get better FE on the mountain but the simple fact is that gravity demands that it takes more energy to move an object upwards than it does to move it laterally.

As such the only uphill differences you can really make are pumping up your tires to lower rolling resistance, letting the engine breathe better (i.e. a K&N air filter), dropping as much weight from the vehicle (and yourself) that you can, using the most rudimentary hypermiling techniques such as light acceleration and braking along with a constant speed (and DWL where you can, if you can) and using lower RPM where possible. Then you just live with the pucker factor until you reach the summit.

If your vehicle does indeed use DFCO (Deceleration Fuel Cutoff, which has already been mentioned in this thread) then reaching a summit is a double boon. Not only are you no longer having to use the extra energy to move up a grade but now you can ride the whole downhill section while engine braking in an appropriate gear without using any fuel at all but still maintaining PS/PB.

You can use the Scangauge's Open/Closed Loop gauge to see if it's in fuel cutoff mode. It should go open loop on the downhills, and then back closed when you actually use some power. It would be nice if it handled cutoff, but this is a rough way to see it anyway.

So the assumption is open loop is a fixed no fuel mode under these conditions?

I'll check this afternoon on my commute home and see if it goes open loop.

Thanks

Welcome, Steve! I think I've chatted with you on GH, haven't I?

I'll defer to the masters here for advice on how to squeeze maximum mileage out of a conventional vehicle. I live in my own little Prius-world with its unique hypermiling capabilities, and I never so much as thought about fuel-efficient driving before I bought it. I think Tom and I were going door-to-door once somewhere in MD. :)

We haven't chatted, but I went back to some of your recent posts and it turns out it was you that mentioned cleanMPG as a place for non-hybrid info.

So it your fault I'm here.:Banane35:

So the assumption is open loop is a fixed no fuel mode under these conditions?

I'll check this afternoon on my commute home and see if it goes open loop.

Thanks

That's right. I could have explained it a little better. Mine does it even when you let off the gas for a stoplight.

I always assumed with my car that coasting in neutral downhill was better than leaving it in gear for minimizing fuel usage. I've always used the scan gauge to determine this. Seems like I'm hearing two different things here or does it depend on the car? Can anybody clear this up?

Don't trust the scangauge when you're coasting down in gear. In neutral, it's accurate, because the engine is idling. In gear, it's wrong. You're using NO fuel. You might want to coast in neutral anyway, sometimes, just to get a longer glide.

I always assumed with my car that coasting in neutral downhill was better than leaving it in gear for minimizing fuel usage. I've always used the scan gauge to determine this. Seems like I'm hearing two different things here or does it depend on the car? Can anybody clear this up?

It depends on the car.

In a ideal world off throttle in gear would be fuel shut of. Some go into injector duty cycle. Its hard to know which cars do this and which ones dont. In the days of carbs. Off throttle in gear coasting, there still was fuel getting to the cylinders. Fuel after all is nothing more than a very light oil. So some injector duty cycle makes sense. Also it would aid in keeping the cats hot and up to temp if a small amount a fuel is flashing off the hot piston, cylinder walls, thus combusting to a point in the cats.

psy

That's right. I could have explained it a little better. Mine does it even when you let off the gas for a stoplight.

So I'm seeing open loop during engine braking as you described.

You explained it fine, but I'm not sure, as other are questioning, whether my particular vehicle does gas shutoff during open loop in this situation. If so, fantastic I can work a strategy with it and spare my brakes.

On my daily commute I am seeing the benefit of long coasts that would be ruined by engine braking, so I'm usually better off in neutral. But I am also occasionally coasting but then having to brake anyways, which I may see better results by engine braking.

Tentative strategy on the downhills, engine brake for speed control, but drop into neutral at appropriate times to build speed and momentum near a bottom.

If the fuel is being cut off during engine braking I should see a significant error at my fillup as the scangauge is figuring fuel use, when I not actually using fuel. I may fuel up at a partial tank after a lot of engine braking as a way to test this.

Somewhere there must be data explaining what the open loop injections are for different parameters, I've failed so far in finding much on this topic with google.

Sounds like a good strategy to me. Unfortunately I can't think of a particularly good source for the hard facts of fuel cut except for an expensive service manual like Toyota techs would use.

You don't need any fancy instrumentation to tell you if your ECU cuts fuel off or not. See the "How can I tell if a vehicle other than the Yaris has DFCO?" section at http://www.yarisworld.com/forums/showthread.php?t=4248 for a simple test you can perform.

Thanks for the link Bailout, great info.
So looks like this definetly appplies to my car then since the xb has the same exact engine as the yaris. So I'll have to keep this in mind when approaching lights where I can coast in gear to slow down and still make it, rather than nuetral and then slight braking. Of course I'll still do nuetral when I need the momentum.

+1

Unfortunately it seems my scangauge will not reflect this, does the scangauge II?

I don't have an SG II to play with yet but from what I've read about it one of its 12 monitoring points is for the Fuel Rate which should do the trick, even if it just goes wonky when you go to a zero fuel rate. You might also be able to use the Engine Load monitor for the same purpose. Any indication should do, really.

A fellow over at YarisWorld has some kind of an AFR (Air-Fuel Ratio) meter and he sees it have a wonky spike right when DFCO starts and then it drops to its leanest possible measurement throughout the remainder of that DFCO status.

If you folks would like to read some Toyota documentation on ECU/fuel injector interaction (Including DFCO) check this out: http://www.autoshop101.com/forms/h43.pdf

Hi All:

___About Fuel Cut. If you have to use your brakes, Fuel Cut w/ ICE-Braking is the best thing going but you should attempt at all costs to DWB. Both ICE-Braking or the mechanicals are FE killers.

___BailOut, I missed the part about driving the mountains down in your PM earlier. If you are coming down a 6 degree slope, it is not long and you will be riding the binders in a FAS so fuel cut is the appropriate solution until such time a stretch is flat enough to climb to maybe 10 over and hang at terminal in a FAS as you bleed off speed. Near the bottom as WorthyWads was discussing, begin a FAS at a point when you will reach some pre-determined Terminal and coast as far as humanly possible while bleeding off due to air resistance or an elevation rise down the road.

___There is a 1,100 +’ drop on I-24 south bound passing through MontEagle, Tennessee. Most everyone that has driven to the deep south from the Chicago area has probably driven through this section of Interstate rather then connect up to I-75 off I-65 while trying to go around … Anyway, you can crest at 25 mph in the climbing truck lane, pull a FAS up to 60 (speed limit down the backside is 55 mph), restart, rev match and ride ICE-Braking w/ fuel cut for the next 3 miles. When the steepest portion of the mountain is clear, you can transition back to a FAS for the last 3 miles at a terminal in excess of 80. This allows no fuel for absolutely scary fuel economy while trying to make up for the FE sucking climb of the darn thing in the first place … It is a bit hairy so you had better have a well handling automobile at those speeds but that last 3 miles while bleeding down to 45 and then into a std. Highway routine is a spectacularly scary and rewarding using the technique(s) as described …

___Good Luck

___Wayne

Thanks everyone for the feedback, especially on the fuel cut-off. That will totally change my approach, and I've already found some applications where I can "Fuel Cut w/ ICE-Braking" (gotta catch up on the correct terms):) on my daily commute. One hill in particular has good potential.

I'm really bummed that the scangauge can't reflect this. :( I guess it is due to each manufacturer using different open loop parameters.

Just a quick check-in to report my success.:D

1904 miles and 59.44 gallons for a 32.03 average.

I'll report more details soon.

Ok I'm gonna try and recap the trip, at almost 600 miles per tank it was mixed conditions for every tank.

1st tank Boulder to Beaver Utah 571 miles and 17.994 for 31.7. Mostly uphill in 3 inches of snow so speeds were slower than I'd planned. Scangauge from boulder to Ike tunnel at 11,200 feet was a sorry 26.4. From there I got in some good engine braking down to Vail, but then a slow grind back up through Vail Pass at 10,600 feet. A little more engine braking from their but the rest of this tank the grades weren't steep enough and the head wind was strong, I was luck to pull off neutral coasts on occassion. I kept her at 65 in 65-75 zones and 60 in 55. On mild grades I just held speed, on decent grades I let it down 10mph or so. Near the passes I was in 3rd trying to maintain 50. When I gassed up the actual fillup was a full gallon less than the scangauge, I was feelin' good.

2nd tank Beaver Utah through heading out of Vegas 568 miles and 18.195 for 31.2. Increased speed to 70. Around 200 miles of this was to Bryce Canyon and then through Zion with 2 laners at 55 or less up several 9000ft passes. Got in lots of engine braking during this. On the way into Vegas I did some long drafting for at least 100 miles, wife wasn't happy with that. Drove out to Hoover dam, awesome but water is low. Hot tip, see the dam at 9am, we had zero traffic delay, but when we left there was a line backed up 10 miles. When I gassed up the actual fillup was a 1/2 gallon more than the scangauge, which surprised me, I though I'd done a lot more engine braking on the second tank.

3rd tank Vegas to western CO somewhere, 566 and 17.998 for 31.4 Held 70 half the tank and 75 the rest. For some reason it seem to stink it up through Nevada and into Utah, the grade is hard to identify, I swear I was going up more than down both ways.:confused: Things seemed to improve greatly, able to neutral some and engine brake too. Then stopped at a wayside and realized we had a good 30mph tail wind going. It was hot ,in the 85 range, normal the tacoma holds 193 but it was more like 198-200, with a peak of 206. Scangauge thought it was unplugged and didn't allow fuel adjustment.

Final tank back to Boulder, 199 and 5.253 for 37.9 Still had the 2 high passes but finally 70 miles with lots of engine braking. Again the scangauge "astericked out", does that way too often? Scangauge said 48.6mpg from Ike to boulder which should be way low considering engine braking.

My normal driving was cruise set at 65 or 70 as I aproach crest kick back the cruise a few taps at a time eventually dropping to 55-60 near top, then checking for engine brake potential, next neutral or simply tap cruise back up to 70. I found that with the wind in my back on most hills that I could engine brake it would end up doing it anyways if I wasn't diligent. At some point I just wanted to get the 13 hour trip over and let her rip at 75.

Overall I'm impressed with the 2.7L, I really didn't put that much effort into maximizing my FE.

There doesn't seem to be anyone else slowing down, I didn't pass a single vehicle that wasn't a truck or RV that couldn't keep up on the grades.

Started trying some FAS with clutch restart on the daily commute, more disappointment with the scangauge as it stops recording miles travel even when in the on position.

Another quick method of testing whether your car does fuel shutoff while engine braking is to tune your AM radio to an unused frequency and turn up the volume so you can hear the motor's ignition noise. If this noise drops out when you engine brake, then your engine has fuel cutoff. This may not work for all vehicles, since some manufacturers may not program their ignition systems to shut off along with their injectors, but it works for Hondas.

Another quick method of testing whether your car does fuel shutoff while engine braking is to tune your AM radio to an unused frequency and turn up the volume so you can hear the motor's ignition noise. If this noise drops out when you engine brake, then your engine has fuel cutoff. This may not work for all vehicles, since some manufacturers may not program their ignition systems to shut off along with their injectors, but it works for Hondas.

I'm pretty sure I'm getting fuel cut-off during open loop, at least once fully warmed. I feel a definite surge at around 1000rpm when it swaps from open loop to closed loop. I'll try the radio noise for curiousity though.

One reason I've finally tried fas is due to one of my best neutral coasts is within the first 2 miles when I can't get open loop anyways and high idle gph and the engine braking kills the momentum as it's only a slight downgrade coming off 55 to a 40 max right turn.

This hypermiling is getting fun.:bananajump:

Just testing my sig, trying to ad my vehicles mpg banner. Yep it worked.:)