Recently I overhauled my exhaust system by putting on new headers, LS cat, and a SIR cat back. However, ever since I put the new system in, I am getting a CEL 74. I tried replacing the ignition wires and even though it cured my rough idle, the CEL 74 is still getting thrown. Do any of you have any suggestions as to what I should try replacing? (dist cap, etc)

 

I had an issue w/ 74-71 before. Are you running an OBD-II ECU? That's when my would come on, then I tried using the Skunk2 OBD-I conversion harness and an XS Engineering P72 OBD-I ECU, and no more CEL 71-74--- which in case you don't know is a random misfire in Cylinder 4, and 3 for 73 and the others respectivly. You haven't done anything w/ your knock sensor, have you??

 

Knock sensor? What is that?

 

OBD1 ecu does not have those codes, that is why you have no more CEL

 

it could be fuel related, but I would try changing rotor and cap.

 

t ... thanks for the reply. I replaced the cap and rotor to no avail.