I'm putting the TPI motor from my 86 IROC into my 91 RS.
I've decided to switch to speed density in the process.
I will also be eliminating VATS and all the EGR/Smog crap.

Would it be easier to modify the stock TBI harness to TPI,
or modify the 86 TPI harness?

Thanks

 

you cant "modify" either

you have to swap them out with their respective engines

 

I think it could be done...the question is which would be a better starting point?
Is there a reason why you think either couldn't be modified?

 

Repinn The 86 Harness, It Will only take you a few Hours. Out of the Car even less.

Modifying the TBI Harness would require you to run New leads for all the Injectors.... Not Fun.


Yes either harness could be Modified, however.

 

thanks Bort

 

sorry, i misunderstood the original question

i thought he wanted to use the TBI harness with the TPI setup

 

Just wait until he gets to the chassis connector and bulkhead connectors. Personally, next time I think I'll just run the leads for the injectors.

 

Why would you have to run new leads for all the injectors. TBI has 2 injector wires, same as any TPI car. All he would need is to put the right TPI injector connectors onto them.
Granted i haven't swapped hanresses in anything myself, but if injector wiring is the big gripe, then i see no issue at all? Like Jza implied, seems like a royal pita to swap entire harnesses compared to just adding injector connectors? What am i missing?

 

i would use the 86 tpi harness..

 

Hummm.....both systems are batch fired, so I would assume each system runs 2 leads to each side of the cylinder banks for the injectors, only with TPI those split up and parallel for the 4 injectors for each side vs. the single one for each side in the TBI.
So I could technically cut the injector circuit where it branches on the 86 harness and splice it in appropriately on the TBI harness.....right? Then I could lengthen and re-terminate the TPS, IAC, MAP, CTS, and MAT sensors leads if necessary. That would keep me from having to go thru the trouble of removing the harness from each vehicle.