I have a 02 z/28 which I have put on hooker longtubes and a y-pipe, k&n fipk kit, bbk 80mm throttle body, and bypassed the heating port for the throttle body. My problem is that when I put on my headers the engine light came on even though I put the sims in place and extenders from the front two in place. The dyno tune shop said everything is hooked up correctly but it was pulling an air fuel ratio code. I was wondering what is most likely wrong with it, what are the mv of each o2 sensor, and any other helpful information that would help me solve this problem.

 

check for exhaust leaks at the header flange. could be throwing it off enough to trip the code.

or change o2 sensors