Have tried both Bosch and AC Delco O2 in this bank, new O2 will run great for a while, then start dropping voltage, telling the PCM to dump fuel, wideband pegging at 9.7 in cruise and fuel trim is +25 lean on that bank. I found the wires burned, so I cut and soldered them back together, only to now have the same problem, 9.7-9.8 AFR and reading max lean fuel trim on the pass bank O2. What can I do to test the wiring voltage and see if the new O2 is good or bad now that I've soldered the wires back together?

 

Wow, no one knows how to test the O2 harness wires to make sure they are good?

 

is the car stock or modified? is there a misfire? if the car is misfiring it will cause a false lean and cause it to be that rich..........also the PCM is not allowed to adjust it that far in closed loop the BLM will pin but not go that rich

 

Heads/cam, no misfire that I am aware of, before I found the burnt wires yesterday I replaced all of the plugs, and all of the old ones looked exactly the same. No header leak that i can hear or see. I haven't tried a new sensor since repairing the wires, is it possible the sensor went bad before repairing the wires? BLM is maxed at 160 or +25 on the pass bank, reading fine on the left bank.

 

swap the sensors and see if the problem follows the sensor to the other bank..........if it does just buy a sensor and call it a day..........try that and post back........

 

go to http://shbox.com/1/HO2S_connector.jpg

 

Signal was at 448 with the sensor unplugged. Tried a new sensor, pulled the PCM BAT fuse for a few min, then drove around for about 30 min, it seems to be running right now, back to normal wideband readings, so hopefully it's fixed.