Fuel Injector shut-off while Coasting

[philmcneal]

Originally Posted by MetroMPG

are you sure your automatic has a cutoff? i'd be surprised.

i noticed teh same thing in my mom's camry automatic when i borrowed it to find its EPA highway speed. while driving through town, the coasting in N beat coasting in D.

i keep telling people, sure you won't have the power of a manual transmission but you can still save gas. Just abuse N and don't use your brakes.... but NOOOOOOOOOOOOOOOOOOOOOOOO people think I'm rubbish....


enjoy paying for the gas sucker. If you haven't noticed, in D there's a potenial truth that somehow the gasoline engine is still feeding power to the torque converter which in turns go to the wheels. With it in N all power to the torque converter is now CUT and enough gas is pumped into the engine to prevent stalling.

By putting it in N you elminate the middle man, doesn't matter if D coasts as well as N, there's still resistance from the torque converter!.

[rh77]

Originally Posted by MetroMPG

are you sure your automatic has a cutoff? i'd be surprised.

i noticed teh same thing in my mom's camry automatic when i borrowed it to find its EPA highway speed. while driving through town, the coasting in N beat coasting in D.

From what I've read, I heard that the fuel injectors give slight pulses of fuel on decel instead of complete cutoff, but I didn't consider it to be a significant amount of fuel. As far as know, it pulses until around 800-900 rpm, then it kicks-into full injection mode to maintain idle, even in gear. Neutral coasting has yielded huge benefits, believe you me.

[mtbiker278]

Looks like I'm going to have to do some more testing on my car. Without the immediate feedback of a scangauge I have to wait through about half a tank to get any kind of estimation. Even then the trfiic around here is so fickle that I could very well see nothing.

[mtbiker278]

Did anyone ever figure out if there was a limit to the speed you can coast an automatic in neutral? There's a hill on the highway that I could coast down but my speed would be around 55-60mph

[SVOboy]

What do you mean by limit to the speed?

[mtbiker278]

is there a limit to the point where it wouldn't be good for the tranny to shift from N to D. I remember seeing a thread from Compaq about this but I think they only resolved the "DO not N-bomb" for an auto.

[SVOboy]

That's only for revving high in neutral. You're transmission should be seamless anywhere if you're not revving it up. My friend's 02 civic will slip in and out of gear at any speed. Lucky him, mine does the whole grinding, jerking, N to D ****,

[mtbiker278]

that's what I thought and hoped for. I've tried it a couple times and it seemed to work ok. I'm just paranoid cause it's still new. I'm starting to think that buying a new car wasn't such a good idea. My 01 civic coupr was awesome cause it was too old to void the warranty but still new enough that you didn't have to worry about it. Still pissed at that bastard that rear-ended me and drove off.

[cardwell5]

If you want to be sure you're car is shutting off the fuel injectors when coasting try this. Put a on/off switch on your fuel pump relay and shut the fuel pump off when coasting or slowing. If you do see an increase in mileage then maybe it's not and if it is, it's not doing it very efficiently. If you don't see a difference then it's working as stated and you need not change anything. Also, check this out. (my invention) http://www.youtube.com/watch?v=kpw_7eTelxg

[theholycow]

This thread has been dead for 5 years.

Anyway, better to hook it up to your fuel injectors. Shutting off your fuel pump will allow your injectors to continue operating until pressure runs out. Not only will that use fuel but it may throw a code for running lean, and it also delays restarting the engine if your fuel pump doesn't build pressure fast enough.

Hooking it up to the fuel injectors is as easy as interrupting the common ground wire used by them all. I don't know if all designs include a ground wire or if some just allow the injectors to ground naturally.