Originally posted by HoosierContour:
At WOT it jumps up to 38% ST fuel trim lean. But the 02 takes over at WOT. So the ST is off no value. The 02 values now read either .93 or .94 and .92 at the secondary actuation.
I'm going to clarify this one, because I doubt you really meant what you wrote. Short version: The O2s are ignored at WOT (along with ST trim, even though it is still calculated).
Long version: At WOT (or really, any event that causes open loop: high TPS/power enrichment, low TPS/deceleration enleanment, O2s not switching yet when the car is first fired), the ST trims are ignored (but still calculated). IIRC the PCM goes to a Load vs. RPM table and looks up a preprogrammed FI open time. Then it adds the LT fuel trim for the current conditions. LT isn't updated but it is used.
