Has anyone had problems with a test pipe causing the primary O2 sensor to become saturated? Im running the AFC hack and recently fouled an O2 sensor after installing a test pipe. I dont know if it's related or not, just wanted to see if anyone else had this problem. I was thinking maybe it's due to less backpressure and therefore causes the car to run too rich. Thanks in advance for your info.

 

if you run an aftermarket exhaust w/ stock cat, have your car tuned, then put in a test-pipe, you'll need to get it retuned. i went from stock straight to testpipe w/ bigger exhaust, and didn't have to have it redone. BTW, i didn't retune immediately after putting a 2.5" cat in. it was basically the same as no cat, but a little cleaner and cost $50 for the 49-states cat.

BTW, your oxygen sensor will foul from running too rich. get a fuel tuner already and fix your problems.

 

No, it is most likely due to a poor tune on your V-afc. Not having a cat wont do anything to the upstream O2 sensor.

 

the tune on the afc is great, i just think the O2 sensor went bad cuz it was old