Fuel Injector shut-off while Coasting

[Silveredwings]

Originally Posted by MetroMPG

yes, suddenly driving has become complex enough that even the radio is a distraction! never mind cell phones, sightseeing, daydreaming...

yeah, that's all I'm sayin'...

Well said.

[mtbiker278]

Originally Posted by MetroMPG

your garage shows your car as a "5AT" - is it an automatic?

my car is an auto with five gears. A first on the civic. I do notice that it likes to hold the gear while deccelerating. It'll get down to about 800 rpms before down shifting when coasting.

So are you guys saying that it is more likely that OBD1 cars do this and not so much newer ones? I know metro said his was OBDII. Is there a way to find this out without having to call a honda engineer?

[MetroMPG]

Originally Posted by mtbiker278

my car is an auto with five gears.

i think it's likely that most, if not all OBDII cars do this once they've reached operating temperature.

but... i believe only cars with *manual* transmissions do it.

if the injectors shut down in an automatic, there's nothing to keep the engine turning (no direct connection to the wheels). the engine will stop when the fuel stops.

[mtbiker278]

Originally Posted by MetroMPG

if the injectors shut down in an automatic, there's nothing to keep the engine turning (no direct connection to the wheels). the engine will stop when the fuel stops.

I was actually wondering about that. I do experience engine braking when deccelerating, but probably not to the point where if the fuel cut off the car would keep going. I keep thinking I should have bought a manual, but the 5th gear ratio at 0.525 is the only thing saving the automatic. I can cruise at 50mph turning over at 1600 rpms.

[GasSavers_DaX]

Originally Posted by MetroMPG

if the injectors shut down in an automatic, there's nothing to keep the engine turning (no direct connection to the wheels). the engine will stop when the fuel stops.

Unless the lockup solenoid is activated... I wonder if this is the case?

[mtbiker278]

No clue. The inner workings of an auto tranny are still a mystery to me. I could tell you all about genes, DNA, and complex molecular reactions, but auto trannies .... it's like pandora's box

I doubt there is a service manual I could get my hands on at this point in time since the car is so new. I suppose I could bombard Honda with e-mails, but I have a feeling they'd be reluctant to share the specifics.

So if the injectors don't shut off completely, do you think that the fuel input would be reduced since there is no load (however I'm not sure if engine braking would be considered a load by the ECU) on the engine as opposed to being at idle?

[GasSavers_DaX]

Originally Posted by mtbiker278

So if the injectors don't shut off completely, do you think that the fuel input would be reduced since there is no load (however I'm not sure if engine braking would be considered a load by the ECU) on the engine as opposed to being at idle?

My intuition would tell me that if any fuel at all is injected, it is very little. My knowledge is solely based off of OBD-1 technology, but I do know that MAP, TP, and RPM all play key roles in the amount of fuel injected, and deceleration is 0% throttle, so that has to count for something.

[rh77]

Via the ScanGauge, I noticed something. I figured that coasting in Drive would be more efficient because of the FI cutoff, but that doesn't seem to be the case. When forced to idle in Neutral and coast, the FE goes up considerably, even at slower speeds. So anymore, I just pop it into N and coast just about anywhere possible, and the results have yielded at least a 1-2 mpg increase, not including more FE with engine-off coasting.

Something to consider...

[SVOboy]

Via the ScanGauge, I noticed something. I figured that coasting in Drive would be more efficient because of the FI cutoff, but that doesn't seem to be the case. When forced to idle in Neutral and coast, the FE goes up considerably, even at slower speeds. So anymore, I just pop it into N and coast just about anywhere possible, and the results have yielded at least a 1-2 mpg increase, not including more FE with engine-off coasting.

Something to consider...

When I noticed that my cel was coming on as a result of decelerating in D (WTF?) I went back to neutral and so far this tank has netted many more miles halfway through,

[MetroMPG]

Originally Posted by rh77

Via the ScanGauge, I noticed something. I figured that coasting in Drive would be more efficient because of the FI cutoff

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

When forced to idle in Neutral and coast, the FE goes up considerably, even at slower speeds.

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.