Ok so I just replaced my o2 sensor with a brand New AC delco unit, single wire unheated. Went around town and all seemed good. Then went for a drive on the freeway and BAM!!! Under medium accelleration it would continue to add fuel into the 9.1 afr range and not come any higher than about 11.1 afr after throttle lift or cruise??? Wb o2 reports very rich! Get home and grab the laptop and its fine under idle and low throttle position untill I make the map rise or accellerate harder, Then it will spike the INT/BLM number to their richest settings,adding fuel-150+blm. Wbo2 reports very rich. so I put the old Bosch or whatever it is back in and continue to watch WB02 and int/blm. All is good, back to normall 126/130 blm/int numbers. Now with the new O2 could it be bad??? It would spike to .004mv under anything more than about 40map or 25% tps. Any thoughts on this?? Thanks for the help. I put the new O2 in because ive heard bad things about the Bosch and other units. Now the problem would be can I still return a used O2 sensor??? Thanks for any help here guys!!!

 

You can get a bad part from any brands box. If what you had in there works keep using it. I have had no issues with bosch single wire or heated sensors.