I'd appreciate any help someone can give me with my t/a engine swap. I have an 85 that was wrecked at 32k miles and I have swapped everything from the 85 into a new body. Now it will only run on 4 cylinders all on the right side. Is it possible I fried the ecm on the swap or could it be something else?

 

What induction does it have, carb or TPI?

 

It has the tpi motor out of an 85 trans am.

 

sounds like you have no fuel to the one bank. figure out if your harness is ok.

 

I have plenty of fuel pressure (45 psi), good spark but my injectors are not firing on the left side. I have unplugged them one at a time and it makes no difference in the way it runs. That's why I'm thinking it could be the ecm.

 

Check your fuses I had the same thing happend to me and it was a blown fuse.
I know that sounds dumb but thats what happened.

 

fuses are all good.

 

Keep troubleshooting the injector pulse on the side that isn't firing.

 

How should I do that? When I first hooked up the wiring harness to the ecm and the electrical connections I found that I had two connectors (sguare) crossed and it would not start. When I switched them around it fired right up but only on 4 cylinders on the right bank. What actually tells the injectors to fire? Thanks

 

What year car are you putting the engine into, there are some differences in the dash harnesses in various years, i.e an '85 harness is different than an 89 and up harness, you may have some injector wires not hooked up

The way to check the pulse, goto Autozone and get a Noid light for GM injectors.

 

I'll get the noid light and check the pulse but I would have to believe that there is none since all 4 on the left side are not firing. As to the wiring harness I did a complete swap, meaning I took every wire out of the 85 body and put them in the 89 body. Thanks for the advice----Tom

 

if you have a 12v test light you can unplugg the injector test it for juice then you will know if its getting power. If the test light lights up you have power. however if i remember the ecm actualy grounds the injectors so if you have power and the injectors arent firing you arent getting a ground signal from your ecm. check your wiring from the injectors to the fuse first and check the fuse for power too most likely thats your issue.

 

IIRC, on the stock TPI's there were fuses or relays on the firewall that had controll over each bank of injectors...

 

really, where abouts would that be located? I've checked the ecm fuse by the battery and that's fine. I'll see if I can locate the relay your talking about and swap it out with a spare one. Thanks for the help---Tom

 

https://www.thirdgen.org/techbb2/sho...injector+relay

same problem as yours. hope it helps.

 

tfg test the injectors for power. Do they have power that will tell you your problem.

your ..

1. missing 12v
or
2. missing signal coming from ecm.

Thats all there is to it.

 

no power but only on one side. It seems to me that the ecm should just shut down all of them together not just one side. I'm going to check that relay in the a.m.---I hope that's it---Thanks for the help---Tom

 

test your fuse for power, do both fuses have power? next check your connector under the passenger side dash. the pink/blk should all have power when the key is on. if they dont you lost it somwere in between. if they do good on to the next test point . if you have power at your dash connector under the passenger side kick panel and not at the injectors your problem is in the harness.

Your ecm provides no power to the injectors only ground. Power comes from the fuse block goes to the connector on the passenger side then runs out through the fender up in to the engine come then to the injectors. Then the ecm provides the ground pulses.

 

Thanks--that's the most helpful information so far!!! I'll go over it in the a.m. and let you guy's know how I make out. Thanks again---Tom

 

Good news-- I traced back the power from the ecm and found that the fuse was not blown but cracked. So believe it or not I replaced the fuse and it fired right up on all eight cylinder!!! Like they alway's say---It's probably something stupid!!! Thanks for all the help----Tom

 

Thats what were all here for I bet you learned too..