I installed a heated 02 sensor, Delco AFS-76. 46.99 at Hi/Lo. They say it is generic 91 to 95 GM. Before I installed it the ecm wouldn't go into closed loop. After I installed it, the ecm will go into closed loop at speeds of around 50, but when speed drops down to 30 or 35, and at idle, it jumps back to open loop. The sensor is installed off the wiper motor power lead. It is grounded on the firewall. Is it still not getting hot enough? I have a 180 thermo installed, would a hotter thermo help? I am not getting the 02 sensor error code anymore, but now am getting the egr code. Thanks.

 

What is the C/L enable temp., and what is the actual operating temp (as the ecm sees it).

Without blocking the radiator on the G Bod runs 132. Some enables are 138 FWIW

 

Bruce,
I may be be lookin in the wrong place, but I do not see a closed loop enable temp in this Prom (in Tuner Cat "ECM constant table"). It is the stock anlw5469 bin for a 7747. According to Autoxray the ecm is seeing between 179 and 183 degrees when the engine is at op temp. Thanks.

 

You should be in the CL operating range at those temperature. You COULD have some other kind of problem(s), like bad O2 signal to the ECU, bad ground/power or a fuel management problem or other wiring problem.


Does the scan tool say OPEN LOOP, or are you guessing???