Just wondering if the Apexi AFC affects fuel control while the ecu is reading off the O2 sensor? I know the computer reads off sensors such as water temp, MAF, O2 and others while adjusting fuel, but is one reading taken into consideration more than others? Lets say I lean the car out for light throttle highway driving to increase gas milage, would the computer even care that I messed with the MAF reading or would O2 sensor signals be more of what it is looking at? Just curious and used to working with carbs, so fuel injection confuses me sometimes.

During closed loop the computer will constantly be trying to make the engine run the way the ecu is programmed. If you modify the MAF to make the car think there is more air, the ecu will still try to get the fuel mixture taht it wants to see from the o2 sensor. If you make huge changes, the ecu may not be able to correct them, but then you will get a CE light. It may be possible to make some small changes during closed loop, but not very much.

Dont hold me to this but from what i've been told the
ecu runs in a open loop until it reaches 100% full throttle.. there fore you just have to drive at 99.9999% and you'll be fine http://www.i-club.com/ubb-files/smile.gif

Actually, the ecu can run in open loop quite often.

In our cars little more than 60% throttle will snap it open.
It's in open on deceleration.
It'll be open when running cold.
There's a good chance it runs open at high RPMs - not sure though.
In 'limp mode', it probably runs open loop as well.

Ed.