my question is do i have to change the interior wiring harness to meet with the engine harness or will i run into major problems? its a 89 camaro TBI to 87 TPI Equipment

 

The '89 harness was the first year the engine and car harness were incorporated into the same loom. You would have an easier time repinning your existing harness to match the '87 TPI.

 

I have done this exact same swap but it was into an 89 formula 305 tbi. you will hit a few things along the way. First thing is the fule pump has to be changed over. My car fired up first turn and then died. The tbi fuel pump is similar to a carb and can not support the higher fuel pressure.

Your intetrior harness is fine except under the hood gm does intertwine the two harnesses together. You will need to change out the spark control unit as well.

I would also upgrade the fuel pump wiring now to an aftermarket setup to increase the wire from 18 gauge stock to 14-10 gauge. This will save headaches dowen the road as well especially if you want to make more power than just 350hp.

I can't think off the top of my head what other headaches I ran itno other than the stock gm wires are not always the color they are supposed to be. Your best bet if you insist on doing this is getting an aftermatrket harness that helps eleviate some of the extra wires from the factory. especially if you are not planning on running all of the smog equipment. Be sure you want to stick with the stock power output now beacuse you might want to hold off and save money by upgrading the computer system to another option. Doing an aftermarket harness allows you to really clean things up by shortening extra wires where you don't need them. I was very happy with how my harness looked after i installed my stealth ram and ran all of the wires to hide as many as possible.

 

i have the whole engine harness and the est and all that its out of an 87 iroc though 305 and i have a 350 computer for it but im just wondering if i hook it up the 89 harness will it work ...it was mentioned that i would need to repin it? to work

 

The computers are the same it is the proms that are differnt.

 

i am going to do the same thing. 91 tbi to 87 tpi, i am still confused on the harness, do i need to use the 87 or the 91? if the 87, what would i do with the interior harness? sorry if you consider this a hijack i am just restaing your original question.

 

You need the harness from the TPI car.The tbi harness is good for only one thing after that and that is to have additional wiring which alway scomes in handy. Again i will suggest to not reuse the factory harness as after many years the connectors and wiring seem to melt under the intense heat that gets trapped under the hood of these cars. There is little if any power benifit to switching to an aftermarket harness other than they shed a few pounds of unneccasary wiring and tir all of the grounds together. Just my opinion as far as the harnesses go. This is a time consuming project. My suggestion too is dont make my mistake, Take pictures of the before and after so you can document what you did.

 

so sice the interior and engine harness is incorporated in te 91 harness, how would that work with the 87? is it still there or what? will i have to use the interior from my 91 harness?

 

[quote=91 camaro racer;3362814]so sice the interior and engine harness is incorporated in te 91 harness, how would that work with the 87? is it still there or what? will i have to use the interior from my 91 harness?[/quote

You have to seperate the engine and interior harness on the 91 and leave the interior harness in place. That is the tough part figuring out what wires are for the engine and which arent. I had them hanging over the side of my fenders seperating the wires determing the ones I knew what they were for and the ones that were undetermined at that time. So yes you reuse the interior harness on your 91.

 

sounds like a job how long did it take to do? complete swap?

 

LMAO!!! it took forever. I was in the Army at the time with months to go and just got everything all wrapped up before I left. Don't forget the things I mentioned of the fuel pump and other hiccups along the way.