Am I saving any gas or just harming something in the car by putting it in neutral at stop lights or while coasting to a red light? I have an AT.

 

leave it in gear you will save more gas this way. The wheels rotation will be spining the engine, and above a certain rpm the injectors will turn off (? - or so i've read, anyone care to clarify?), if you leave it in neutral, you will burn gas b/c nothing is spinning the engine but its own combustion. I believe that people with scangagues can confirm this.

 

I have 5MT and I used to downshift every time I'd come to a red light. I've since learned it's just better to leave it in gear til you brake til about 15mph then put it in N or 1st. I prefer N so I can keep my foot off the clutch while I wait. For auto I wouldn't mess with it, in Sport mode I would just downshift or wait til I came to a stop then shift it back to 1st.

 

Put the AT tranny in neutral. I know this is true because I have sat and watched(timed the mpg drop) in my wifes 2008 CRV AT. I forget why but someone on here stated the reasons why.

Also, if you are at a long enough(12sec or more) stop/light then turn the car off.

Since you have an AT DFCO will be your friend along with neutral.

 

What is DFCO? So why do some of you say neutral, others no neutral? I thought I watched it drop slower in mpg in neutral as well.

 

DFCO = Direct Fuel Cut Off

This is when the ECU cuts fuel to the injectors/motor when driving in gear but only when you are not pressing the gas pedal. This will slow you down because it also equals engine braking. DFCO is only good until about 1500rpm in a MT and I believe it is only good until 1100rpm in the AT FIT(don't quote me on that). DFCO saves fuel but slows down the coast. Use is wisely.

Why people say what they do, to be polite about it, is because they don't know but want to make people think they do know, they believe they are right, or spiteful.

My guess is that someone somewhere told them what they spat out. All I can say is seeing is believing. If you have a SGII then you can find out for yourself. I know for a fact in the 2008 CRV AT neutral is better than Drive while stopped. I would be willing to bet Honda has designd all their ATs like that. I would be willing to bet that most ATs(reguardless of make) are like that by default as well. I beileve I read some where that was the case but since I am not concerned about proving who is right, then it doesn't really matter. I know what works for me. Figure out what works for you and run with it.

 

I usually downshift unless there's no time to downshift i just coast in neutral.

 

when your stopped, I would imagine neutral would save gas because the engine doesn't have to overcome the friction/viscosity of the torque converter. Is it bad for it to shift back and forth at all the long lights though? I don't know that one...

 

I have a Scangauge II, but which gauge setting tells you the fuel flow has been shut off? It's not obvious to me, looking at the manual (http://www.pureenergysystems.com/sto...SGIIManual.pdf, page 6-7). The closest seems to be "FPR" for fuel pressure, but IIRC this is always blank (the manual says few cars report this).

 

i used to work in a transmission shop specializing in torque convertors. shifting between neutral and drive does nothing harmful to the transmission or the car would not have it. all it does is allow oil to flow freely through the transmission without the valves forcing oil to the torque convertor fins which stalls (or creates an oil lock) the torque convertor and makes the planetary gears start rotating. the torque convertor is bolted to the flywheel so regardless of what gear you have it in it is still spinning as fast as the engine.

 

As a person who does it (not like others who are "ive heard this is that n blah blah), going from drive to neutrel and back. It actually does save me gas, dont think i go from 30 mpg to 50 mpg but you do save gas in the least. I always do this when i go down a hill (you find that alot here), coasting to a stop, car gets in front me, or slow down for a on/off ramp. I did it on a SUV too, no harm. and hey, it is a gas saver. i do keep it in neutrel tho even when the light is red, as someone had mentioned, the friction that starts from the engine, through the rods through the axel or w/e the energy is used to spin the wheels. friction causes the engine to work "harder" therefore more RPM, simple as that, doesn't take a rocket scientist to figure that out. One thing i do use to see if im actually saving gas, is i look at the Tacometer (i belive thats what its called: RPM gauge?), i keep my foot off the pedal look at the tacometer, hit the nuetrel, if it goes lower (lower RPM) then your saving gas. if by some reason it goes up (ive seen it happen, idk y >.>) then stay with the drive. although i woudnt recomend going from sport all the way to neutrel, too much "shifting" for the car, thats from a opinion perspective, not fact (not sure), thats y i wish automatics would have clutches, kinda like a pressure activated neutrel pad

 

Does anyone know the right information about DFCO, if it actually shuts off the injectors then that should help MPG alot.

 

Think of the gas and brake (yes brake) as money pedals. If you need either of them it's costing you money.

Neutral & Coasting is your friend.

Too much on the gas pedal ...well thats obvious.

If you need to hit the brake or downshift and use DFCO well... you've used too much gas getting there.

If you can coast to a stop... most efficient. Stay in neutral at the light and shut off the engine if its lengthly.

If you've overdone it and need to slow down... downshifting using DFCO is the next best thing.

Braking is the most costly as far as efficiency goes. Your bleeding off wasted energy you've generated.

Now of course I'm NOT saying not to use your brakes... Duh! I'm just saying, your plan of attack should be to minimize their use.

Now neutral at a light in an AT? Umm... engine pushing on the transmission to propel you forward at idle... you ...push on the brake to prevent that... 2 opposing forces working... sounds inefficient to me!

JMHO obvoiusly..

 

Make sense to me. I used to try DFCO in my AT but I feel that it slows the car down too much. Its good if you're costing to a redlight, stop sign, or stopped traffic, it seems like the best bet. But if you're just going down a large hill, I find that DFCO slows the car slower than Id like to go. I put it in neutral and keep my speed up for the most part, but with using less RPMs than if my foot was on the gas or cruise control was on.

I just started putting it in neutral nearly every chance I can with added DFCO when coming to a full stop and I noticed that I gained about 20 extra miles at the half-tank mark. Normally I get about 150-165ish miles to a half tank, this past tank with using neutral a lot i got 190 at a half tank with all other conditions the same.

 

The Owners' Manual says to put the car in Neutral (AT) at stop lights.

 

It does? Awesome.

 

With my '09 AT at a stop, the ScanGauge II shows fuel use at about .29GPH in gear, and .18GPH in neutral with the engine warm. When the engine is cold, the difference is much less.

Coasting down long hills in gear generally causes GPH to drop to zero, but a very gradual hill may not, where neutral will use less fuel.

zukered,

The Gallons Per Hour (GPH) or Liters Per Hour (LPH) is probably the most useful for monitoring this, though some custom setup of the ScanGauge II will help.

Set the gauges to display Throttle Position Sensor (TPS) and note the value displayed at no throttle. Mine is 13. The Cuttoff value should be set to four above that, So I set mine for 17 (p16 in the manual).

When the ECU reports an open-loop condition with no throttle, the GPH reading goes to zero, indicating injector cutoff. LP (closed loop/open loop) can also be set as a gauge option.

 

Wow. I never knew that. I believe you, but I'm gonna go check that tomorrow morning. And i'll see if it says anything else about the shifting.

 

if you stop for more than 10sec, then put it in N, but if you stop for less then 10sec then you don't need to put it in N

 

Won't shutting off/turning on your engine at stops put extra wear on your ignition and or/spark plugs?