89 305tbi came out 85 vette 5.7 tpi going in please help
 

New member here, just bought a project 89 iroc off a guy and want to do this right. The 89 iroc body/ wiring harness is set up for a 5.0 tbi. I'm putting in an 85 5.7 tpi with matching tranny out of a corvette. I have no harness and the guy gave me what he said was the computer to the tpi motor but I don't know if he was truthful or not ( it has "6128 hand written on it in several places if that means anything).

I'm just trying to figure out what harness to buy, where to get it, how much, and if I have the right computer. Please bear with me, I'm new to the forum and also TPI motors and camaro but trust me.... I'm gonna be around for a long long time. I'm starting the build of my ultimate childhood fantasy car.

Thanks - Gary

OK just googled the number on the hopeful computer and it popped as an airbag module. I thought the guy was fibbing.

I think you are ok with your 305 harness. If I am remembering right the 5.7 L98 was an option on the 89. You need the right prom for the L98. I think the vet injectors are a little bigger but there used to be aftermarket Proms flashed for that upgrade. I also think it will run fine with the Camaro Prom and vet injectors in close loop because the O2 sensor will just shorten the pulse width to the injector. You are just leaving some power on the table.

The above information is based on working on them side by side NOT doing the conversion. There are a lot of TPI 305 converted to L98 350’s out there. There has to be write ups somewhere.

Thanks for the detailed response but I was told it was factory TBI not TPI ( it came with a throttle body and TBI intake). I better look at the harness because the guy was telling me whatever just to get the stuff sold.

The 305 IROC came both ways, either with EFI (TBI), or TPI.

TPI (Tuned Port Injection), multiple injectors, one for each cylinder and its ECM,
will not interchange with TBI (Throttle Body Injection), having two injectors in the body, on the engine.
Tank fuel pumps are different.
I suggest you buy a Haynes manual on the model of Camaro and compare the Emissionsand Fuel chapter.

My bad i forgot the IROC came in the TBI. I did so many 305 TPI motors I was just remembering them in the Irocs.

About 10 years ago I did some research on putting a TPI L98 350 in a 87 Monte SS. If I remember right I could us the harness can computer from an 87 TPI Camaro with a aftermarket PROM. I had to fab up something for the Fuel but you could just use the stock L98 factory setup. I would imagine the parts are available through chain type parts store and making up fuel line is not a big deal.

OK now we're getting somewhere! I think my easiest solution is getting a painless wiring harness for a 87 camaro 5.0 or 5.7 tpi and computer to match. Not sure what a PROM is though. And then a fuel pump for a TPI motor at the parts store. Sound right? Thanks everyone.

You want to check the fuel line size. You TBI may be a smaller diameter. The old ECU's could not be flashed. They use a memory chip (Programable Read Only Memory). So an automatic and standard shift car could have the same ECU but differnt PROMs. When the factory wanted to update the programming they just shipped out new proms.

305 amd 350 most likely had the same ECU with different Proms. Current aftermarket may do it different. Camaro 69 might remember but somewhere around 1989-90 the Vet had the first flashable memory. We had a IBM CAMs system we could plug into the Vet and GM could flash it over a modem. Even if the guy gave you the Vet ECU it may not have worked with the Camaro harness.
(Ha how many people know what a modem is )

Yep that should work. You will also need. 87 350 ECM, 87 350 ESC module, 87 350 knock sensor, 22lb 350 injectors, and finally 87 350 CUSTOM PROM CHIP