I just baught a Speed density TPI system off e-bay. I will need a wiring harness and i found one from jegs for $297.00 for the painless wiring harness. From what i have read is that alot of your accessories will not with one. Like the wipers ac and stuff like that. Anybody know if this is true. Also can anyone give me a good idea on what all parts i will need to swap from TBI to TPI. Oh yeah and here is a link to the system that I bought--->1990 Speed Density System I beleive it is a very nice system.

 

The Painless harness is just for the engine and tranmission - nothing else. I hope you haven't ripped out your entire main vehicle wiring harness. I took out my original MAF harness and swapped in a 4' extended Painless SD harness. My car runs fine, the Painless kind of acts like a stand alone for my motor as is. The factory main vehicle harness runs all the accessories, and guages, etc.

 

due to the options that gm offers and engine combos the computer
harness is usually pretty seperated from the chassis harness.
gauge wires, alternator, a/c usually are bundled with the computer
but usually exit to the driver side. and the computer exit to the
passenger side.
the aftermarket harnesses only support the engine and transmission.
i build them for street rooders and engine swaps.
airdeano

 

You build the wiring harnesses? I just need one that will make my swap over to tpi as easy as possible and will also make everything work like its supposed to. I can't beleive gm wants almost 900 bucks for a wiring harness. I still got to get an ecm and prom but those are cheap. Got to get all the sensors and things plus the fuel lines and pump but i could get all the stuff i need for less than 300 bucks. Just that darn wiring harness at 900 dollars. Could you make one for me and if so how much do you want for one.

 

https://www.thirdgen.org/newdesign/tech/tbitotpi.shtml

Have fun!! I'm almost done with my 89 L03 to 89 L98 swap. Cant wait to hit the track when I'm done!! The only thing I didnt agree with from the article above is the bit about the fuel lines. Yes you'll need a different fuel sender and other misc fuel system parts, but the fuel lines themselves will be fine. The size of the line affects the volume of fuel that passes through, does not affect the pressure (and pressure is the only thing that changes from TBI 16-18 psi to TPI 40+ psi).