I'm removing the TBI wiring harness from a 91 rs to swap it to a MAF TPI set up and I cannot figure out what is what...it looks like the chassis harness going to the starter for the ignition is all one harness and ties into the ecm harness then goes into the fuse box threw the driver side fire wall......I'm ready to blow my car up....my tpi setup is out of a 87 iroc and it is going on a 5.7 that the previous owner put in my car. any help would be GREATLY appreciated.

 

87 and older had an independent ECM harness.
88 and newer have other underhood wires joined with the ECM harness.
So yes, you're seeing that correctly in the 91.

You really should look into modifying the TBI harness to turn it into a MAP/SD TPI harness. The MAP/SD and TBI harnesses share a lot of similarities. And the MAF TPI isn't smog legal for 1991.

 

ok cool...thank you for that....I was going nuts and me and my friend were getting frustrated lol. Smog is not a issue so that does not matter. I have that 87 TPI ECM harness and it is a MAF harness but, if you can point me in the right direction on converting my 91 TBI harness to TPI. The MAF TPI itself came out of a 89 Iroc 5.7 so it does not have that 9th cold start injector. I can use the MAP sensor from the TBI if I convert my harness TPI.

 

Read the sticky thread in the TPI forum on repinning.

 

I read all of this and it will change it over to a MAP/SD harness.....my question is can I place a MAF system in the car. I jade a MAF tpi and a 87 MAF ecm and harness but the problem is......to even take the 91 ecm harness out.....it is intertwined with the chassis harness. I'm just stumped.