I know this is tpi board, but I need to know why my 88 5.7 computer dosn't start the engine when swapped w/ from '86 5.0 tpi to '88 5.7 tpi. thanks

 

I need you to explain the whole scenario.

-- Joe

 

I have an '86 Iroc clone that according to the vin code use to be a six popper Sport Coupe. The 5.0 that was in it ran great but a little rich. The 5.0 is tpi and looks like an '86 engine (see pic). The swap looks complete and professional as though dealer installed. So I rebuilt a L98 5.7 from an '88 GTA and dropped it in. Street strip cam, mild head & intake port & polish, roller rockers, gear drive, headers and Accel ignition. Now the 5.7 computer won't start the car but the old 5.0 one will. I kept the same harness because the Painless Wiring harness was the same part # for '86 & '88. The '88 computer clips right in. There is also a Bosch unit attatched to the computer w/ it's own harness, what is it? Can the 5.0 unit be programed to run my 5.7 right? The car runs great with the 5.0 computer but I can't help think I'm missing out on some power. Thanks for reading, any help

 

The 88 ecm MAY have vats and that may be the problem.

Try removing the memcal from the 88 computer and put it in teh 86.. See if it will fire the car. If so, the ECM is fried. If not, its VATS.

You should start considering prom tuning if your engine is modified.

-- Joe

 

The donor car didn't have vats

 

Both the 88 and 86 computers "should" be the same. The issue could be the memcals or the ECM's.

do what anesthes said and see what happens.