Does anybody know if the ECU shuts the fuel injectors off when decelerating, especially when left in gear?

 

This has been talked about on css.net, and most people agree that fuel cutoff only occurs while in gear.

Take that hypermiling thread lol

 

Without thinking this out entirely....

Wouldn't the engine stall if the fuel injectors stopped the fuel from injecting....nothing to combust.

Seems to me, if you were decelerating by removing your foot from the gas pedal while going down a long hill, for instance, the engine would stall...no steering, no brakes...

 

Manual transmission...

 

Does it matter???

 

Yea i mean for your engine to operate it needs gas, how would shutting the injectors down keep the engine running? I'm confused

 

In gear, the momentum of the vehicle keeps the motor turning.

 

DCFO does cut fuel to the injectors, on both auto and manual trans. There are a bunch of parameters and tables that control how it works. The only differences between the auto and manual calibrations are related to speed in gear due to ratio differences. Otherwise the same.

In a vary basic sense, it will work above certain speeds and RPMs. It will disable below certain thresholds and that is why the engine won't stall.

 

Are we talking about HHRs here? Fuel never cuts off when the engine is running and if it does the engine stops running, so there is a problem. Only a hybrid shuts off all fuel injectors and vehicles with "Active Fuel Management", such as Tahoes and Suburbans, cutoff 4 of the 8 cylinders at times.

 

I was hoping someone more knowledgeable would step in JoeR, hehe. I thought it was only for manual transmissions though.

This information was discovered with hptuners wasn't it?