ok last night i wired up a switch so i could switch between the narrowband and wideband output of my plx 300. narrow band for normal driving and wideband for datalogging and tuning. i also made up a resistor pack which plugs right into the old o2 sensor plug to simulate the o2 heater. (i know i can just disable it in uberdata, but the chip im currently running was made by someone else and i dont know how they have the o2 setup). anyway it runs pretty rich, like 11-12:1 throughout the map. i expected this and its not too bad so whatever. but the thing that concerned me is whenever i abruptly let off the throttle it goes way lean. like to the point where my plx unit just says "lean" or "air". then it goes back to normal after settling on the idle or if i blip the throttle a tad. now is this normal? is this safe? or am i just being paranoid?

 

This is normal. When you decelerate, your injectors turn off.

They kick back in at 1100rpms...

 

gotcha. thanks

 

i always wondered what that was....i knew my wideband wasn't spiking out at 21/1 for no reason

 

Its called Fuel Efficiency.

I always used to think that if you were coming down a long long hill...that it was best to put the car in neutral and let it idle as you coasted down the hill...you actually use more fuel that way than just coasting in gear

 

1300 rpms OBD1.

If you can fiddle that "idle rev limit" I bet you can idle a set of real big guns at 1300-1400 rpms. The $35/per 1500cc Ranger/Taurus or 1600cc F-150/Marquis units. Having the idle cut off raised helps the engine "catch" at idle on engine decel. If Blakey-poo cared enough to raise it, I could have a certain set of 1100cc injectors idling at 750 rpm instead of 1000-1200 rpms...

Yum.