rfomlover

Hey guys. Having a few issues with my 01 cobra. When I bought the car, it had an O/R MAC Prochamber on it. The Rear O2s were supposedly turned off in the tune. The rear O2s have always been in there and plugged in with out MIL elims. I changed my mid pipe to an O/R X Pipe. Everything was ok at first until I hit a bump and the position of one of the rear O2s in the new pipe made it snap in half because of the ground clearance. The car then started to throw a code with no MIL of P0136. O2 circuit something like that. So I just decided since I dont need these anyway, and they are turned off, I plugged the holes. Car is now throwing codes of both O2s being wrong. P0136 and the bank 2 equivalent. The MIL doesnt come on until about 50 miles of clearing codes but right after they clear they show right back up on the tuner. After 50 or so miles the MIL comes on again. Dont know what to do. What I really want to know is if the rear O2s matter in the way the car runs like whether its richer or leaner or something. Thanks.

Drag5.0mustang

Rear o2's don't matter at all on how the car runs... You can leave the light on if you want.... No effect on anything.

rfomlover

Even before with the MAC it didnt smell nearly as rich as it does now.

Drag5.0mustang

Still... Has 0 effect rear o2 are pretty much for emissions **** (catyltic coverters)... Disconnect the battery for 30 sec to reset the computer so the car can re learn its self...

rfomlover

Cool will try thanks.

cliffyk

That the PCM is throwing those codes (P1136 and probably P1156) means that the O2 sensors are not turned off in the tune, or incompletely disabled...

There are three scalars that have to be set to 0 the completely disable the rear sensors and cat efficiency monitor:

rfomlover

Thats cool thanks for the picture.

russellthelovemuscle

i was thinking of deleting my o2 sensors, my tuner told me the rear 2 are useless to me but deffinitly keep the front 2

JRad405

Well depending on your inspection and the strictness od emissions tests that could be a problem.

cliffyk

It is true as all the rear sensors do is monitor catalytic converter efficiency, however if not turned off in the tune the MIL (SES) lamp will be on all the time; so if some other problem arises you will not know about it.

And from what I understand about CA emissions tests there's no way you'll pass even if they are turned off in the tune...