i went and swapped around my exhaust again, I have a true dual setup with no cats out to flowmaster 40 series, the O2 is in factory location, after driving for ~5-10 miles the Check engine light comes on. What is wrong here? gonna go pull codes in a few...

'86 stock L98 iron heads, cut air lid and new exhaust.

EDIT: code 13

 

Code 13 is oxygen sensor. This thread will give you some ideas:

http://forums.corvetteforum.com/c4-t...-question.html

Try that for a start. Obviously, make sure the wire is connected and not cut somewhere.

 

Doh! apparently the guy that did the exhaust forgot to hook the o2 back up.. I didn't think about looking at it..