Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I am trying to get direction on a lean condition. I have a lot of info but I have hit a wall. LTFT is fixed high (25%) throughout the rpm range except at WOT. At WOT it will jump down to 4%. The STFT will occasionally go negative up to about -10% but basically hovers around zero. Both O2 sensors are new. The ECT-IAT-MAF have been checked. I have smoke tested the intake. I have tested fuel pressure-current and injector flow and the ignition primary current ramps are good. The car runs pretty well (300K). My main question is regarding the LTFT. It is a flatline. Why is it not moving? How should I interpret this?
The LTFT is max'd out. The engine is getting so much air that the computer cannot compensate for it unless the 02's are stuck rich. At WOT, the 02's go into open loop. This is a default for WOT.
It would be help full to post some 02 voltage data. Have you tried to drive the 02's lean? With 300k on the engine, might be mechanic, valves, compression ect.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
Thank you for the reply. I have created rich and lean conditions and the O2 sensor does respond to both. I can't scope the O2 until the weekend, but both sensors are new. There is no evidence of a vacuum leak as of yet.
