Here's my dilemma, my current set up is a '89 305 TBI. I have a complete 1990 Formula 305 TPI donor car. I want to do an engine swap to make mine a TPI. Will it be easier for me to also change the wiring harness under the dash cluster instead of splicing and dicing it to fit my '89 harness?

Should I also install the vats module from the donor car since I do have the keys?

BTW, I will also be updating my whole interior to a '91 interior. Which will be the perfect time to do the rewiring.

Please let me know.

 

putting a new harness isn't that bad to do pluse you are no going to need the mass air flow

you might want to check to see if the fule pump is going to work the TBI and TPI have dif pumps Tpi puts out more psi

 

Yeah, I know I have to change the fuel pump to a TPI pump. Besides, my sending unit needs replacing.

 

Unless you are changing out the steering column or just want to swap lock cylinders there is no need to swap out the VATS module.

 

OK I got it on the VATS module, but I will have to change my steering column, it's all jacked up. I'm going to use a steering column off another car and do a VATS by-pass.

 

89 camaro harnesses differ from 90 firebird harnesses your in for a huge headache the dash harness problems are the headlight switch, cigarette light, cluster wiring, and I believe in 90 the wiper motors wiring was put in the headlight harness but your 89's wiper motor harness is in the ecm/main engine harness

re-pin your 89 tbi harness to run the tpi

 

O.K. how about this, since I don't want to do any re-pinning and I also have a ’91 donor car(bought it dirty cheap for the interior and ground efx). Now that wiring harness should button right up to the 1990 tpi harness. Although it’s from a 3.1 V6. But that shouldn’t matter, should it? Since of course I’ll been changing the ECM to the TPI’s.

My only concern is time because I’ll only have about 3 weeks to basically redo everything in my car. TPI engine swap, transmission, posi rear end, electrical and completely redoing my interior. All that’s left is a paint job.

 

The '91 harness (for a 191" V-6 MPFI) won't be a direct swap for your '90 TPI setup. You'll have a lot of work to make it fly. Repinning at the ECM may be the fastest and easiest.

 

OOOOHHHH, after doing some extensive research everybody that replied said repinning would be alot easier. So that's what I'll do. I already got the conversion chart from another link in the tpi page.

Now I'm only confused on the VSS and the TCC because some were having problems with them. But I'll be going by the chart, hopefully there isn't any errors.

Thanks everyone for knocking some sense into me.

 

the 91 V6 dash/chassis harness will be a dead perfect match for the 90 TPI harness...

 

Yeah that's what I was think since the '91 v6 is also SD and runs the same ECM 730 but with a different prom. I have a 730 ECM for a 305 TPI and I will be completely updating my interior from a '89 to a '91, including the dash and the instrument cluster. And I don't mind switching the harness; it will give me a chance to learn more about my car.

If anybody else has a suggestion or comment, please let me know.

 

But you'll have to add a couple injector connectors, alter the harness length for the TPS and IAC, probably the CTS, and possibly for the AIR valves. The rest should be the correct length. It won't be a completely "plug & play' harness.

 

It seems either i'm confused by what he's saying, or you havent fully read what he's posted.

He is using an engine harness from a 90 TPI, he shouldnt have to make any changes, he is planning on using a dash / harness from a 91 V6 camaro, which the two will make the whole deal a plug and play swap.