desmond

while driving home today on the highway i was checking out the sensor menu in the etc menu on the pfc commander looking at my o2 sensor readouts. i remember reading a post not too long ago that said that if your o2 readout doesnt stay constant during low load cruising situations then i have a problem. well my sensor jumps all over the place during cruise, from .82, to .72 and down the back up. but at full throttle i see .91 or .93. can anyone tell me what this means? also it fluctuates during idle.

and about the tps. VTA1 and VTA2 are off by a little. VTA1 is .94 closed and 4.96 open and VTA2 is .41 closed and 4.96 open. while this isnt way off, should i still attempt to adjust the tps?

tcb100

The O2 sensor is supposed to fluctuate between say .8 and .2 as the ECU richens and leans the motor in response to the o2 reading. If your O2 sensor ever stays constant at idle or crusing it is either not warmed up yet or broken. The stock o2 sensor is unheated, meaning it won't start generating voltage until the exhaust heats it up.

A cat needs a rich mixture to burn up some emissions and a lean mixture to burn up others so the ECU adjusts the mixture, rich, lean, rich, lean to get that burn going.

At WOT the O2 sensor is not contolling anything. That .91 or 93. is just a measurement of how rich you are running.

desmond

ahh okay, so its supposed to fluctuate at higher rpm since its only do something at lower rpms. what about at idle?
and what does .91 or .93 translate to in afr's? i would guess pretty rich right?