I have a 90 Firebird and I am currently trying to end work on a TBI to TPI changeover and I am having some computer problems. I have a stock rebuilt 305 bored .60 over, a 89 camaro TPI setup, got a "Painless" wiring harness, 90 TPI ECM with custom chip, and a MSD ignition. The engine runs fine and the car will drive, save a few problems...the computer won't control the timing at all, it also won't show up on a scan tool, and the speedometer doesn't work. Different computers have been tried along with differnet chips and the same result. The work is being done by a friend of mine who is a GM certified mechanic and is a wit's end as to what the problem is. All wires have been checked individually and are where they are supposed to be going and have continuity. If anybody has any ideas I'd appreciate it very much.

 

yeh i heard about the problem with the speedo also on the change over have u figured out how to fix it yet. Im going to do the change over soon also

 

This thread should help with the speedo problem.

https://www.thirdgen.org/techbb2/sho...BI+TPI+swap+VSS

 

jr305 link didn't work.


My recient post should help

https://www.thirdgen.org/techbb2/sho...hreadid=186359