OffspringZ28

after scanning the car and finding the cause of my hesitation stumble, which was the left o2 sensor stuck at like 1190mv. now correct me if im wrong but arent BAD 02's usually stuck at like 450mv? so i unplugged my 02 and i am running in SES mode......no hesitation no stumble, everything is gravy and still managing 220+ to a tank. my theory is that somehow the gauge is wacked out cuz even though its supposed to light up when the key is turned to "ON" it doesnt. im thinking that maybe because it was stuck at like 1190-1200mv is cuz the gauge is powered by a 12v source right? maybe the wires are screwy cuz i had a performance shop install a nitrous kit and there are wires everywhere on the fuse panel. maybe the 12v power is somehow going directly to the computer causing a crazy condition and stumble, etc. anyone have any thoughts? humor me.

Injuneer

What "gauge" are you talking about? Do you have an A/F gauge? If so, simply try disconnecting the O2 sensor lead from the gauge, to insure it isn't somehow causing a voltage leak from the +12V power supply to the sensor wire. You can also get voltage leaks from the O2 heater wires (+12V) to the signal wire on the sensor if you crush the wiring harness.

If you've got stray voltages telling the PCM it is pig rich, and it starts pulling out fuel that doens't need to be "pulled out", its probably not going to run very well with the sensors connected. By disconnecting the sensor, you aren't running in "SES mode" (I don't think I've ever heard of that)... you are running in open loop.

OffspringZ28

well i get confused between open and closed loop so ses mode = limp home mode, etc. car does run fine in open loop though