Rb20det runs rich once warmed up

[dtowngoalie]

I start up the car and it idles fine at about 900 rpm and the afrs lean out as the car warms (140*) up to about at about 15.8 where it starts to backfire a bit. Once the car hits 150* aprox the afrs just slowly become rich to about 11.0. Not sure if its a bad coolant temp or something else. The computer is not throwing any codes. Also I'm running a Cerifo ECU with a r32 CTS. Could it be anything besides the coolant temp sensor?

[dtowngoalie]

Carl H nailed this one on the dot. The ecu goes out of cold start mode at 65* celcius (150* F) and gives control to the O2 sensor. Turns out my O2 took a s***.

[zmannz]

Thanks soooo much for posting that... I have a check to do.