Went from 305 TPI in the '87 IROC to new 350 HO 330 crate engine, new injectors.....but, i don't have timing advance. Does the electrical input start from the MAF sensor for timing advance? Does the PROM in the ECM need changed? ....Good Golly,,,,help!

Stan

 

I was told to up feul pressure to 50 lbs and use ecm from 350.go to page Tech/General Engine then go to thread going from 305 to 350 in 1991 gta. maby this will help you. from tagta 1991.

 

I had the same problem when I went from TBI to TPI then back to TBI (don't ask). I am now going carb because I discovered that the circuit in my wiring harness that controls timing was fried somewhere and I didn't feel like tracing it. It could be several things, though. First, check knock sensor, then ESC module. In fact, the ESC module may be the key, since you're going from a 305 to a 350. You will need an ESC module specific to a 350 (It's a different p/n). If this doesn't work, check your distributor. If you remove the cap, there is a black module which the wires from your harness plug into. Remove that module and take it to the parts store to have it tested. If bad, replace, and your problem should be solved. If it checks out and you have done everything else mentioned above, have fun tracing wires!!!

 

Thanks for the responses. The ESC is cheap enough; i think under $10. Will this leave me with needing to alter the PROM to compensate?

Stan