I have posted similar threads here many times before and have gotten some useful information but I could use some more....

I have a 1991 RS Convertible that originally had a TBI 305 and a TH700R4 transmission.... I am at the tail end of a few year project that I really want to put the wraps on by this spring.... I have swapped in a GMPP 350 and a T56 transmission both are bolted up a ready to go... I currently have a MAF TPI system of off an 87 GTA that is also bolted up... my only problem is the wiring harness. The harness I have is in rough shape at best and it could be worked with if I had to... I would not be against buying a new aftermarket harness (Painless?) but if possible I would like to use the one I have due to cash considerations. The harness I have appears to have all the main engine management controls on it but there is no fuse block connection and odds are that some other things are missing... this leaves me with a few questions. Just FYI... the new TPI fuel pump has been put in and I have the computer out of the 87 where I got the harness... I do plan on getting a PROM done. Also, I am deleting the Air Conditioning and the A.I.R. system out of the car.

So here we go... these are the basic questions I have.

#1:Is there anyone that could give me some good advice on what needs to be done to make my current TPI harness work. It looks like it has to be combined with my old TBI harness, but I can't quite tell how.

#2:Some good information on aftermarket harnesses. Are painless harnesses a good way to go for my project? Are there any other options?

#3:Will the deletion of my AC and A.I.R. cause any problems... and if they do can I just fix that when I get my PROM done?

#4:Anything else that anyone could think of about my project? Any snags that I may not have realized?

I really miss my thirdgen and would love to have it on the street by April so any information or help at all will be greatly appreciated. Thanks for your time.

 

I used a 89 Formula Harness in My GF's 91 RS. when we moved from V6 to 350 TPI. It was a mess. Although we got it going. I would advise to get a 91 harness. Its a direct bolt in and go. But if you plan on doing it, the fan turn on wire under dash will have to be relocated, the underhood light will blow the acc fuse everytime the maf system s hooked up. Your going to have to cut the wire in the C204 connector and ground it or your injectors wont fire as well. Theres also numerous other little changes that need to be done. I'd look to Trickster for more diagrams. He hooked us up before on them.

 

From what i understand about painless is the harness will work the fuel injection only......If you're gonna buy a harness i'de take a look at this place...http://www.speartech.com/. Just a thought

 

They look fairly promising but that is a bit out of my price range ($600-$750 yikes.).... are there any other decent options for a wiring harness. If there is an aftermarket harness that will hook straight up gauranteed I would be all for it... but I would like to see something more affordable. Thanks for the suggestion though Mr. Roush.

As previously stated... I have put a huge amount of time and money into this project and really want it to be rolling by spring (Which feels really close especially since it has been in the 50's around Chicago lately).

Anybody else have good suggestions... if you have anything please just throw it out there...

 

I've converted plenty Camaro/Firebird harnesses from TBI to TPI. If you sent the original harness to me, I could convert it for you. The price would be far less than Speartech. I could alternatively build you a brand new harness that would plug into your I/P connector and be the correct length for your car. When I build new Camaro/Firebird harnesses, I used a template I have drawn out from a original TPI harness. If I built a new harness, you'd have to splice a few wires near the driver side bulkhead connector. If you sent me your original TBI harness, you won't have to splice wires. Please contact me privately (mike@s10wildside.com) if you're interested.

 

TBI to TPI

If I remember right, the Painless Harness does not come with the smog pump connection... which wouldn't matter anyway, since you're removing it.

Removing them will cause no problems...

 

Sorry for the hijack, but what is this C205 connecter that has to be grounded? Is it applicable to a '747 conversion?