I took a TPI motor out of an 88 IROC and put it into a 91 RS. I know the dash board is different, and gauges, speedometer, etc will not work. I have searched and searched and searched for a 91 harness out of a Z-28 and can't find one. Does anyone know, If i plug the harness for the 88 into the 91, will it fire the motor, minus all the gauges, etc?

 

I'm guessing the 91 RS was a TBI. I think your 88 motor is a Mass Air Flow sensor motor. probably need to take the 88 ECM with the motor. I'd suspect your 91 TBI RS wiring harness is probably useless, but you'd need both wiring diagrams to eliminate that. not sure if the TBI had a MAP sensor. for sure the MEMCAL is different.

there's vendors that sell TPI SD and MAF wiring harness, but they're not cheap.

there's postings on this site that go into this kind of stuff in excruciating detail.