Any Big Savings In Coasting In Neutral With Engine On?

[digitaldissent]

thanks for the video, that kind of think is very helpful

[Arminius]

I bet my car slows 2-3X faster in gear. That can't be more efficient.

[cfg83]

dsq -

I would never EOC with an automatic unless I knew everything about it's design. Coasting in Neutral is easy for me because I have a manual tranny. The RPMs drop much closer to idle, and the Scangauge *shows* me how much MPG I am gaining. Coasting in neutral is a big part of Pulse and Glide (the mild kind with engine on). I don't know what the benefit will be in an auto because they're designs are less "predictable" in terms of their design/behavior.

CarloSW2

[cfg83]

Arminius -

Originally Posted by Arminius

I bet my car slows 2-3X faster in gear. That can't be more efficient.

Correct, but (big) if you have automatic fuel-cutoff while "coasting in gear", then it can be strategic. If you see a stop up ahead, coast-in-gear to engine-brake and get fuel-cutoff for free.

CarloSW2

[cfg83]

thebrad -

Originally Posted by thebrad

Not scientific by any means, but according to SGII I get better fuel economy coasting in gear? Possibly a false positive.

...

I made this video yesterday on the same topic for another forum.

Yeah, I think you have fuel-cutoff going for you. The best way to confirm would be to splice into the fuel injector pulse wires like they are doing for the MPGuino, but when I see that 9999 (divide by zero => largest number that can be displayed), I think fuel-cutoff too.

Another (indirect) way would be to get an A/F gauge. If you see the gauge go super lean when the SG shows 9999, then it would imply that you have fuel cutoff.

I wonder if you can see your 02 sensor output with an X-Gauge function. It's a 1996 Honda, so it *might* be available to you. Hard to tell. I don't know because I don't have a 1996 Civic.

CarloSW2

[Gregte]

With my GMC 2.2l fuel injected coasting in neutral uses fuel whereas coasting in gear turns the injectors off and uses no fuel. This is true if the coasting speed (engine RPM) is fast enough.

I live in a very hilly area. going down many of the hills requires braking, engine braking or otherwise. If I were to put it in N going down the hills it will use fuel at the rate of engine idling, and I have to apply the brakes to slow down. But if I leave it in gear it uses no fuel going down the hill and also serves to slow the vehicle.

In my vehicle coasting in N only helps FE if the engine is OFF, and even then it only makes sense if I do not want the engine brake affect, which I often need where I drive.

[thebrad]

Originally Posted by cfg83

thebrad -



Yeah, I think you have fuel-cutoff going for you. The best way to confirm would be to splice into the fuel injector pulse wires like they are doing for the MPGuino, but when I see that 9999 (divide by zero => largest number that can be displayed), I think fuel-cutoff too.

Another (indirect) way would be to get an A/F gauge. If you see the gauge go super lean when the SG shows 9999, then it would imply that you have fuel cutoff.

I wonder if you can see your 02 sensor output with an X-Gauge function. It's a 1996 Honda, so it *might* be available to you. Hard to tell. I don't know because I don't have a 1996 Civic.

CarloSW2

Willing to try it "for science" if you can give me the XGauge coding.

[Tony Raine]

This is something i had to try.


as far as my rig, (auto transmission) coasting in N was not beneficial

test 1, coast to a stoplight in gear
test 2, coast to a stoplight in N
test 3, coast in N, engine on, at 55 on the highway

in test 1, engine dropped to around 400 rpms
in test 2, engine stayed at around 1200 rpms
in test 3, transmission got "confused". the trans started hunting gears with a lot of slipping of the torque converter

so basically i learned to just get my foot completely off the gas as much as possible with the engine still running. when i get to a stoplight i know is going to be long, i put it in N after i come to a complete stop, then turn off the engine.

i'm curious to see how this effects my mpg, hopefully it will help offset the added weight of a trailer, wood, and construction equipment i've been hauling on part of this tank.

[jjackstone]

Hi all,
I have an '03 Taurus 3 liter automatic. I have done the coasting both in gear and in neutral. What I see on my SG is about a 30% mpg gain if I coast in neutral. for example if I show 60mpg in drive, then shift to neutral, the there is a corresponding increase to about 80mpg. I have found this to generally be the case. I do not glide at over 40 mph although so far I haven't found any problems shifting back and forth at speeds below that. I do have about a two second time delay for the tranny to return to the proper pressure for whatever the current speed might be before I re-engage the throttle. Otherwise there is lag in the acceleration and then a sudden jerk when the tranny engages.
At stops, there is almost always a 30% loss in economy if left in drive rather than neutral. Ex: idles at .29gph in idle, .40gph in drive. So I have to conclude that yes there is some savings by just slipping into neutral.
JJ

[reaper1001]

I drive down several large hills on a daily basis and just recently i decided to try coasting in neutral. Its fairly easy as I drive a standard so when it comes time to go back into gear i just rev the engine to where the rpm should be and shift back into gear. I got a 4mpg gain which is a 20% increase for my vehicle. Stop signs and such i do the same thing mainly because i have to otherwise i'll stall but 900rpm should be better then 3000