Newbie with some questions about changing driving
 

I just started reading stuff on here about hypermiler and whatnot so I am wondering how to do some of this stuff. Btw, I have an automatic transmission 97 Cutlass Supreme that averages 24-26 mpg.

First of all, is pulse and glide just for hybrids? Secondly, with that you are putting it in neutral AND actually turning the car off (thus losing the power steering, power brakes, and whatnot)?

Also, is it good (good FE + not bad on the car) to put it in neutral and coast to stop or is putting it in neutral meaningless with the engine still on? Keep in mind I have an automatic trans.

IMO with automatics, it's pointless to shift into neutral and would seem to cause more strain on the trans than necessary.

you'll notice with automatics when you let off the throttle your RPMs drop to idle speed anyway.

Usually the RPM's don't drop. At least with newer cars. Until you start slowing down.

It will help to go into neutral IF it would otherwise hold it in gear at high rpm. If it drops down to idle rpm anyway, there's no benefit. As long as the engine is running, there's no danger at all to the transmission.

my wife's 99 cherokee does the second i let off the throttle.

i can't recall the last time i drove an automatic that didn't. i always thought it did it to save on fuel.

My wife's 04 Odyssey holds the gear almost all the time. I suspect other Honda autos are similar.

Yours is better for FE.

Pulse and glide is not just for hybrids. I have an automatic and shift to neutral often. It depends on if you need to maintain speed or slow down for a light.I usually don't turn the engine off unless I know I'm going to come to a complete stop. Coasting to a light in gear is better than using brakes,because the wheels turn the motor instead of the force of the pistons.Coasting in Neutral is more efficient because you don't lose speed as quickly and can coast further;providing there is space to do so.
When coasting with the engine off, you still have one good brake application,so don't get back off the brake and reapply. I lightly apply the brakes to slow down and gently increase pressure as I near where I need to stop. Power steering will be lost. so just don't do it when you need to turn or be prepared to apply elbow grease.
Check to see if your car can be FLAT TOWED. If not, there's a transmission lube problem that could cause damage coasting with the engine off.

lol, there's nothing FE about the IL6 cherokee's. i'm lucky to get 18 highway with a tail wind and no load.

Haha, yeah, you're right. :D
The whole package is bad, but the transmission is better than mine.

checked the manual, it says it shouldn't be towed on the drive wheels. So my car pretty much can't be flat towed unless I use dollys or something under the front wheels. So then I can't use pulse and glide with my car?

You can use P&G, just leave the engine running for the neutral glide part. Does it say something like "under 35mph and less than 50 miles"? If so, you can turn the engine off at "under 35". They were willing to put it in writing and risk lawsuits, so there's probably a safety cushion built in there as well. I'm not recommending that you exceed the specs, but you probably can. ;)

It doesn't specify. Doesn't sound like I should do it at all.


So what CAN I do? Other than the typical maintenance stuff (tires, air filters, etc) and driving the speed limit. Doesn't sound like hypermiling with an automatic can yield very significant results.

I'll let you all know if my gas mileage is any different after I check it the next time I fill up. This is my first tank of gas using these techniques so I'm interested to see if there's an improvement.

If the engine is running, you can glide in neutral ALL DAY LONG. That will definitely help your mileage. My civic idles at .3gph, so it you're coasting at 30mph, that makes 100mpg. Mixing any amount of that into your drive will help the average.

Also, try driving as if you have no brakes. Use extreme forward-looking anticipation.

My cars transmission (automatic) downshifts as your speed drops instead of just dropping to idle.

YMMV as they say... Neutral coast vs in-gear coast efficiency will depend on the deceleration fuel cutoff logic that your GM ECU uses and the RPM range, gearing and TC lockup points. Motors generally have relatively little frictional loss below 3000RPM, but this goes up to 20% of the motor's output at 5-6000 RPM, so it's possible that if you've got overdrive gearing and it's loafing along at 2000 RPM with the TC locked at 60mph, and the DFCO acts down to 1000RPM, and the TC stays locked up when you take your foot off, down to some reasonable speed like 30 or 40mph.. then what you may find by experiment is that P+G between 60 and 40 is more efficient in gear than neutral coasting. If however, the TC unlocks and the revs drop quickly below 1000 when you take your foot off, or it downshifts early, or you have high gearing, so you're slowing in the 3500-2500 range or higher (Engine friction higher), then you may find that coasting in neutral is more effective.

GM ECUs are meant to have a semi mythical lean burn mode at steady state cruise, so you might try driving 60mph steady, and seeing if that seems to make a difference. We often hear of folks with buick V6 powered vehicles, the 3800 or later versions thereof, getting low to mid 30s highway.

Hypermilling etc..
 

It is nice to see someone else with a Cutlass Supreme on here. Have a 91 myself.

Tried neutral a couple of times, not sure how much it helped though with mpg.

The car itself is pretty good for gas mileage. Here are a few things that I have done to increase my own.

-Using 5w30 instead of 10w30.
-Using cruise control
-Installing an air dam on the front (still in testing this week)
-Limiting/eliminating use of a/c

Hope this helps
Joel

so should I try and see if P&G helps any without shutting the car off, but just going in neutral?


and thanks Joel for the info

You are very welcome.

Joel

Yes, Most of my P&G is with the engine on and it does work; though the pulse part seems like it's using lots of gas, the glide more than compensates for it.
Cruise control saving gas is debatable. Most people can out preform the cruise if they are paying attention.It may help if you're tired and don't feel like hypermiling.

Personally cruise control has worked. Last few days been acting up, need to get it checked.

Early on that is what made a difference.

Joel

We have a section for automatics, check it out. I have posted some info there from my 94 intrepid automatic.

I wrote a [hopefully decent] summary of FE strategies that have helped me with my non-hybrid automatic.
https://www.gassavers.org/showpost.ph...4&postcount=12
I could repost it here but it's kinda long. One thing I didn't bother with in that post which might help you is a simple, free modification that you may be able to do. If your car has a cable (not an electric wire, but a cable like a bicycle uses for brakes) going from the throttle body to the transmission, adjusting that cable can make it stay in a higher gear longer when you step on the gas pedal. See https://autospeed.com/cms/article.html?&A=1304 for a complete explanation, except that article adjusts it in the other direction for people who are more interested in driving fast than saving gas.

another quick question...when you pulse and glide, how fast are you accelerating for the pulse? Like normal acceleration, moderately fast, or nearly floor it?

I pulse at the rate of a wheel-chair power up to 5 above the speed limit, then glide to 8 or 10 below the speed limit, if and ONLY IF, it will not downshift into a lower gear. Typically I can only P&G on 45mph roads where I get up to 50, put it in neutral, slow to 35, and put it back in gear. In my car, a '96 Saturn, under 35mph downshifts into 3rd.

Also, keep in mind, P&G should only be done (in my opinion) once the car is up to operating temperature and never in traffic or bad weather conditions. It's just too risky to be in neutral when you may need to make a fast reaction. Same goes for turning the car off and coasting... I ONLY do that when I'm traveling more than 10 miles on the highway with little traffic, do it in the slow lane only.

well I filled up my tank today for the first time after the new driving techniques...was pretty disappointed. I'm assuming I made some mistake somewhere. Maybe the last time I filled up, it wasn't as full as I thought. Anyway, I went 205 miles on 8.7 gallons of fuel for an average of 23.56 mpg...a little below my average. I don't really know what would explain it. I coasted WAY more than I ever normally did, never even used the accelerator pulling into the driveway which is something I always used to do, and even tried the P&G (tho not shutting the car off) a few times. I'm thinkin that in P&G I didn't pay attention to the RPM and might have actually lost gas mileage by doing that, but even so, I didn't do it much at all.

and Project84, what do you mean about the wheel-chair??

This doesn't make too much sense to me, after looking at the BMEP/RPM and SFC graphs.

I was under the impression that the idea of P&G was to attempt to maximize engine efficiency by:

1. Reducing losses due to throttling
2. Operate at optimum BSFC

The way I try to accomplish these things are, during the pulse:

1. Open the throttle 50 to 70 WOT
2. Keep RPMs at 2,500 to 3,000

I have an automatic, so it's a bit of a pain in the butt to open the throttle and maintain RPM without the damn thing shifting.

I've been experimenting with P&G in the last couple of weeks, at my next fill-up I'll have some mileage numbers. The last 2 times I filled up, I didn't have a "standard fillup protocol" so I'm not confident in trying to quantify the difference that my P&G technique may have had on FE.

I think the other consensus you'll find on this board is that you need a ScanGuage. I need one, for sure.