Nissan Car Lounge - Almera, Juke, Latio, Qashqai, Sylphy, Teana Owners > Latio
My FC Getting Better With Low RPM
Ying:
--- Quote from: SoL on December 16, 2008, 12:34:18 AM ---When idle, yes, fuel is consumed.
However, when in gear, like D, something called deceleration fuel-cutoff (DFCO) takes place. From what I observed on my 4AT, at speeds above 45, when you lift your leg off accelerator, the fuel injection cuts-off. Instead, the engine is kept running by momentum from the wheels.
Fuel injection continues when your speed is below 45 in D, when the engine rpm isn't enough to keep the engine running. So normally when stopping, i'd go from D to OD-OFF to 2, then stop. Helps save some fuel.
This is not a very good way to go downslope unless you're planning to stop or you're going too fast, as engine braking is still not as good as coasting in Neutral.
This feature has been in cars since 92, if i'm not wrong.
--- End quote ---
Yes, while in D, once I release my right foot, I believe the controller cuts-off(or should I say greatly reduce) fuel to helps slow down the car from higher speed to ~30km/h. Then it will inject some fuel even I dont touch the pedal.
while idle, car speed is below 30km/h right? so the controller will inject fuel even you dont touch the pedal.
Ying:
--- Quote from: SoL on December 17, 2008, 11:44:14 AM ---Yes, idling is discouraged because idling occurs when you stop, which means engine rpm is not enough to keep engine running without using fuel.
At high speeds like 45 and above(for me), when u lift your leg off accelerator, fuel injection stop, thus engine braking. If you don't believe, try this:
1.Get your speed up to 70-80km/h.
2.Release accelerator. Your car speed should slow down very fast. This is engine braking, and no fuel is being consumed at this point.
3.At around 45km/h, you should feel a jerk as fuel injection resumes and your car is free wheeling(less engine braking).
This is tried and tested on 4AT. For CVT, your mileage may vary.
--- End quote ---
yeap, the jerk happen ~30km/h+ for my CVT.
SoL:
--- Quote from: Ying on December 17, 2008, 11:54:50 AM ---Yes, while in D, once I release my right foot, I believe the controller cuts-off(or should I say greatly reduce) fuel to helps slow down the car from higher speed to ~30km/h. Then it will inject some fuel even I dont touch the pedal.
while idle, car speed is below 30km/h right? so the controller will inject fuel even you dont touch the pedal.
--- End quote ---
Yes, thats right. But its not greatly reduce, its cut-off.
Jazz:
--- Quote from: SoL on December 17, 2008, 11:58:34 AM ---Yes, thats right. But its not greatly reduce, its cut-off.
--- End quote ---
It not totally cut off, once your engine is burnt off fuel, the ECU will still tell the fuel injector to inject fuel to maintain idle speed, else if you idle too long, your engine will stalled if you do not depress your accelerator ?
SoL:
Im sorry, im a bit confused.
So you are trying to say fuel is not cutoff when idling? Yes, thats right, because idling happens when u stop, and rpm is not high enough, thus fuel is injected.
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