I am beginning the process of converting a 1989 RS from TBI to TPI. The TPI components I have are only the hard parts, also from an '89. I want to convert the TBI harness over the TPI but do not have the pinout or wiring diagrams to consult.

From the many searches I have done, I know I will need to change the in-tank fuel pump, add relays etc. for the MAF burn off relay, create a wire harness to connect the MAF, injector harness connectors, and some other misc wire mods in the engine bay.

Will the stock '89 TBI ECM work for this conversion by replacing the TBI MEMCAL with one for TPI. I am sure there are some additional headaches I am not aware of.

I have searched and am unable to locate this info, any help would be appreciated.

Thanks, Andy

 

You cannot use the TBI ecm, you will need one for a TPI car(1227165). The chips are not interchangeable.
You will also need a new throttle cable, and a new kickdown cable. The TBI ones are too short and have the wrong ends, and an air filter assy. I'm probably forgetting some small stuff, but you will discover it as you go along.
When I did mine I bought a complete harness from someone parting out his car, made the job much easier.

 

TBI to SD TPI

https://www.thirdgen.org/techbb2/sho...hreadid=216453

You'll need to get the injector connectors, ECM and a few extra ECM connectors.

 

Andy,try this site. It helped me out alot on the wiring end.
http://www.chevythunder.com/

 

Thanks to everyone, you have been a big help with this PITA project.

 

I just finished my 91' Chevy truck TBI to TPI. I used a painless wire harness. I also changed out all sensors to TPI just to be on the safe side. You'll have to extend the fuel lines and of course change your fuel pump. I used a new stock 350-TPI Delco in-tank pump.
Just fired it up today.
Good luck

 

The stainless steel lines are a nice touch.