Injector behavior under zero throttle situations???
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,094
Likes: 5
From: The 7th layer of hell - Western Washington
Injector behavior under zero throttle situations???
What does the motor do under an engine braking situation - say when you are coasting down a long hill in gear with your foot off the gas. Does the motor just barely retain enough injector cycling to keep the engine running, or does it shut them down completely?
This started with a conversation on which would be more economical, coasting down a long hill in neutral and letting the engine idle - or keeping it in gear with zero throttle...
This started with a conversation on which would be more economical, coasting down a long hill in neutral and letting the engine idle - or keeping it in gear with zero throttle...
Supporting Vendor
Joined: Jul 2003
Posts: 6,486
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From: http://www.mphparts.com 800-364-1975
The injectors can never be completely off for any extended period of time while attempting to maintain a constant RPM. The motor needs some amount of fuel to keep it turning when the car is in neutral.
LSxs do have a provision in the PCM called DFCO (decel fuel cutoff) that occurs when the car is decelerating. Using your example, going down a hill in neutral, the injectors would close (provided the car is within DFCO enable boundaries as specified in the calibration) until the motor hit idle speed and then restart to maintain idle.
While the car is in gear, I suspect but cannot answer with certainty (since I have not tried it, not too many hills in FL
) that DFCO would shut down the injectors at least periodically if not entirely while you are coasting and the engine is within parameters for DFCO to enable.
Hope this helps.
LSxs do have a provision in the PCM called DFCO (decel fuel cutoff) that occurs when the car is decelerating. Using your example, going down a hill in neutral, the injectors would close (provided the car is within DFCO enable boundaries as specified in the calibration) until the motor hit idle speed and then restart to maintain idle.
While the car is in gear, I suspect but cannot answer with certainty (since I have not tried it, not too many hills in FL
) that DFCO would shut down the injectors at least periodically if not entirely while you are coasting and the engine is within parameters for DFCO to enable.Hope this helps.
