1G New o2 Sensor, intermittent voltage fluctuation at idle

[mr2krazee]

Just wired in a Bosch o2 universal sensor. I Dont get a constant fluctuation at idle only here and there. I know it worked right I've triple checked. Is this normal or should I have constant fluctuations at idle?

 

[92AWDHX40]

What kind of fluctuation you mean is it cycling? What indicator are you reading for fluctuation?

 

[mr2krazee]

I am data logging with MMCD via laptop. I watch the o2 voltage and it sometimes does not cycle as it should when idle. It cycled the whole way home from work today. I just installed this sensor a few days ago. My low fuel trim keeps pegging lean no matter how I set my MAFT and my mid and high go rich. The car keeps sensing knock (20-43 counts) when I'm just cruising no matter what I do I've been fighting this since I got it a couple weeks ago. I setup the MAFT for the car but have been trying to tune out the problems but it still persists.

 

[steve]

If the conditions are correct the ECU will enter closed loop and you will see the O2 sensor voltage switch back and forth. That is the normal case when the car is at operating temp and idling or steady state cruising.

 

[mr2krazee]

If the conditions are correct the ECU will enter closed loop and you will see the O2 sensor voltage switch back and forth. That is the normal case when the car is at operating temp and idling or steady state cruising.

OK thank you. That is good to know. I have looked all over but everywhere I have read people say if it zereos when idle then the heater circuit is bad. Now I just need to figure out the random knock at cruise and lean low fuel trim.

 

[steve]

I just need to figure out the lean low fuel trim.

If the sensor is bad the low fuel trim could be caused by it, or it could be telling you the same thing as why the O2 isn't cycling.

fueltrimupdatepoints [ECMTuning - wiki] talks about what's required to enter closed loop and additionally the conditions for updating the fuel trims (Learn Mode).