Im slowly getting my fuel where i want it to be.. i was having alot of problems with ng48 so ive swapped back to ng30. With the exact same fuel/ignition maps on ng48 the car would run extremely rich, enough to easily see the gas not being burned. My question is, when you are backing off / engine braking.. is it normal to go lean? i can keep the fuel about right until i back off and it seems to lean out pretty badly. does it hurt the engine to lean out at that time? thanks!

 

When you let off the gas, the Throttle plate shuts closed. When the ECU sees the Throttle plate closed and the engine is higher than 1100 RPMs, it should shut off the injectors and use engine compression to slow the vehicle.

I say should because I have observed the injectors staying on at random times with various versions of the OBD0 code...sometimes it does it right, sometimes it doesnt.

Obviously, when the injectors shut off...your Wideband will read lean...mine tells me 20.9% Oxygen, which is what Air is.

 

Same here. I alway's wondered why it read lean but I assumed it was due to the ecu not dumping as much fuel in at that given time of closed throttle.

 

Hmm, i think i will try scaling the fuel down quite a bit then. At idle i seem to be at about -18 vacuum.. but when im going down the road and let off the gas, its closer to -30. it also starts billowing gas smoke.. i think im gonna lean it way out below -20 and see if i can get it to quite smoking some. thanks

 

Are we supposed to worry about this ? cause i always wondered.