Cant get codes from computer PLEASE HELP

I have done a 4cyl swap on my sons 92 lx with a 5.0 it has the following, mass air, hi po air induction ,E- cam ,Gt-40 intake, 65mm Tb ,full mac- exhaust, headers, h pipe ,ect.Heres the problem the check engine light has been on since the swap and the car is burning very very rich the plugs were black when I pulled them.But I cant get a code one out of it ,I thought it was my code reader so I went and got a new one and still came up with nothing., could my computer be bad I just bought it for the swap it was used but I got it from a guy thats pretty reputable around these parts I just want some advice before I get him involved. PLEASE HELP!!!!!!!!!!!!

Could be.....Any possibility of swapping with someone with a known good ECM?? These boxes are a dime a dozen at the junks. Just make sure it's an '89 - '93 5.0. There are several versions of these, too. Since you have mass air, I think the last year for speed density was '88 and you can't use that one. Check on corral.com - they've got lots of info over there and have a forum just for 5.0's.

thanks ill do some more checking