Does shifting into neutral save fuel

[LS1notFOUND]

The power steering does work with the engine off and key on run (and maybe on acc idr)

However it does not work if you are stopped or below a certain speed ~10mph..

I know this is true bc with the key off while moving the vehicle is fairly resitant to turning, turn the key while still moving and presto power assist.. the wheel lock only engages after the key is removed..

*note I am not responsible for any incident attempting this manuever and do not recommend trying it
(Even if I do it)

Back to the coasting debate I haven't done any testing so I can validate a comparo but I have hit 49.5 mpg on a tank of gas coasting in nuetral. (Hand calc. 1.4t 6mt). So I'm happy throwing it in nuetral, its easy. Lol

-tyler

But is that simply because "at speed" its easier to turn the wheel anyway? does it bring itself back to center on its own? Guess I'll try it and see.

Wow i didnt realize in order to get near decent mpg you had to damn near risk death by doing something stupid like cutting yout car of or disengaging your clutch downhill

These treads should have ideas on steps to try to het a recall on faulty fuel mileage or refunds for fraudulent and misleading advertisement

Heads up im just sayin next time a poll goes out asking how much you are willing to pay for gas ti support a war + 4.00 isnt the right answer! :+( you tend to get what u ask for

First off, your 3 "troll style" posts could have been....oh my god! 3 paragraphs in 1 post!

Second, haven't we already determined your sonic is loaded up with aftermarket goodies that do nothing but hurt MPG?

Guess what, my stock 1.8L lives life in the 30mpg world and on trips driving pretty fast starts going into the mid-upper 30's!

 

[Larry]

Simple test: Using a scangauge or ultragauge, set up a gallons/hour gauge and have it showing. Coast in neutral and read the gallons/hr, then coast in gear and read the gallons/hr. Whichever is lower, that's more fuel efficient.

However, neutral can allow you to coast for longer periods of time and if you're hypermiling that can provide better mpg. But for normal everyday driving, you'll get more mpg just driving the car normally and coasting in gear.

 

[mitdr774]

Is there a way to have a decel fuel cut set up through a tune? Last time I looked at it with the ultra gauge (based on instant MPG since I didnt want to spend 20 minutes trying to find the correct screen) I was not going into decel fuel cut when allowing the car to coast in gear. I was showing better results by disengaging the clutch or putting it in neutral.

 

[Larry]

Is there a way to have a decel fuel cut set up through a tune? Last time I looked at it with the ultra gauge (based on instant MPG since I didnt want to spend 20 minutes trying to find the correct screen) I was not going into decel fuel cut when allowing the car to coast in gear. I was showing better results by disengaging the clutch or putting it in neutral.

There has been reports of certain cars not reporting dfco correctly to gauges, but I assure you it is working.

 

[Eric Smit]

Tap the brakes briefly and the fuel cutoff will show.

 

[mitdr774]

Guess I will have to go play with the ultra gauge and see if I can find the correct parameter to display.

 

[Eric Smit]

Oh it's not a parameter, and sorry Larry but you aren't technically correct.

My super loud exhaust only pops when I am in closed loop, which on decel means my fuel cutoff isn't working. If I tap the brakes, the popping stops and I go into open loop, which is when my fuel cutoff starts working.

 

[mitdr774]

Looks like I will need an exhaust to figure this out....

Been planning on one for a while anyways. Second cat delete and probably the SLP exhaust. Should help it breath and free up another MPG or two, i hope.

 

[Eric Smit]

Technically not better MPG, but anyway.

I only used my exhaust as a reference. If your gauge isn't showing the cutoff, tap the brakes and see if it is. Don't hold the brakes, just a quick light tap. On the other side, a quick jab of the loud pedal will disengage the cutoff. Fun facts.

 

[mitdr774]

I did do a quick spin and the B1S1 O2 did drop to 0.000 when i let off the accelerator. Look slike I need to get used to viewing O2 values in Lambda. Not used to those readings.

 

[CoHPhasor]

Although there are some good pieces of evidence as to engine cutoff, etc, I do have to note the amount of drag on the car while in-gear going downhill.

If you shift into netrual your "exit speed" from a hill is much higher than staying in-gear.
Are the savings from cutoff really so high as to cancel out the amount of fuel you use to regain lost speed?

I was going down a hill the other day in neutral and exited ~70mph.
Down the same hill at the same starting speed in-gear and exited ~52mph.
The limit on the road is 65 and is usually driven by motorists @ 70.

Just asking what thoughts are.

 

[Eric Smit]

You must have a tiny hill. I have a hill I drive every morning and I can go down in gear off the throttle and exit the hill faster than I entered.


-Eric Smit

 

[silverwolf72]

I drive down a 6% hill about 5 miles long and taking my foot off the gas I go from 75 to 60mph within a mile with car running at about 2000rmps.
1.4L Automatic

 

[CoHPhasor]

^ Exactly.
I mean maybe down an 8% grade it might speed up, but the automatic may be different than the manual in this way.

I'll put mine in manual Thursday night and see if not downshifting helps.
(I haven't felt the auto downshift itself while going down the hill, but this'll make sure)

 

[Eric Smit]

Oh, that's right. You have an auto. Totally slipped my mind.


-Eric Smit

 

[CoHPhasor]

On the way home did the decent-ish hill again.
At the top I was @68mph.
I completely lifted off and put it into "manual"(auto) mode.
The car stayed in "M6" the whole time and at the bottom I was @ 48mph.

I decelerated by 20mph.
Going downhill, in an automatic, neutral is absolutely the way to go.
(If you're going to use the momentum at the bottom that is)

 

[mitdr774]

Try it again in normal auto mode. From my past experience just abot every auto with a manual setting provides engine braking while in the manual mode. Normal mode did not provide engine braking, except the Allison behind the D-Max of course.

 

[silverwolf72]

For what I've experienced anything over 1500rpm I get engine breaking

 

[CoHPhasor]

I tried normal auto and it was the same.
I also tried it again in neutral and only dropped 9mph instead of 20.

Something I find annoying that I just discovered is that in manual mode, although I can force high rpms but not upshifting, I can't force an upshift unless I'm at an rpm the computer likes.
(meaning I can't force a gas-saving higher gear)

Interesting to continue the discovery process.
(Hell, I know that a tune will help my mpg but I like knowing as much as possible)

 

[sx sonic]

On the manual trans I've noticed something that feels/hears like the ecm is trying to maintain speed or atleast not engine brake after I let off the gas (6th gear). It will only last a few seconds and then norml engine braking resumes..

The reason I think its the ecm trying to maintain speed is 1. I will only lose 1-2 mph over 3ish seconds and then ~1-2mph every second afterwards. 2. The exh sounds different after a few seconds (quite, then the no fuel "cackle" type sound that accompanies engine breaking and it starts as it slows down faster). 3. I've never felt or heard such a condition while in 1st, 2nd, or 3rd..

If it is indeed the computer trying to maintain speed (for drivers with sloppy foot control I assume) I have not been able to detect a change in mpg according to my Ultra Gauge before or after the transitions. However my UG does indicate I get higher mpg when coasting, and ultimately I can coast longer than if I let offat the same spot and engine breaked the rest of the way.

any one else notice something similar??

-tyler