some O2 sensor questions


Active Member
Mar 8, 2005
I was watching my cc on my O2 was basically stuck while driving...orig. O2 LOL. So I bought one and put it in at the shop before Icame home. Totally different car. I would've never thought it. Drives and runs awesome now. Question I have...the cc only moves while driving. It cycles as fast as it should. But if you are stopped at a light with your foot on the's not cycling. Explain that to me please..LOL. Brand new ACDelco sensor (purple single wire). The O2s are cycling like they should now and the numbers are much richer than they were...thank goodness I own a wideband and egt...that's what I used to tune the fuel curve before.
at idle there is not much fuel adjusting as if you were crusing down the road.
I'll bet you it also has something to do with the open loop idle on Eric's chips doesn't it?
I saw the other sensor die while it was for sure bad. What clued me in was that my O2 numbers went from 790s to low 800s down to LOW 700s all of a sudden. I flipped over and checked the cc...and they were stuck while driving down the road.
My O2's are all over the place at 35mph.steady run yesterday it would go like this and my idle went to sh-t 035-126-700-750-266-820 sensor is only 2 mos old guess i got a bad one (it was like watching attack of the killer tomatoes in high def) :biggrin: changin that thing out today .
My O2's are all over the place at 35mph
That's exactly as it should be. When the engine gets into "closed loop", the ECM will try to control the A/F to 14.7, and as it makes corrections, the O2 readings will cycle, back and forth, from high to low. Because the Scanmaster doesn't see every change, it looks a little more random, but on a DirectScan, it will look like a wave.