Need Help - 3.4 to LT1 wiring issues
 

Ok Lately ive converted a 3.4 firebird into a lt1. Evrything went smoothly but wiring for the 2 extra cylinders has me stumped. I ran the 5.7 harnes to the 3.4 harness to fire the 2 other injectors. But its still loading up the 7 & 8 cylinders. Please guys help me out. Thanks Rich.

What did you do? You still have the 3.4 engine harness? I'm confused

Say what?

yea whaaa....? did you swap the entire engine harness??

I combimed a 5.7 engine harness into a 3.4 body harnes. And put in a lt1 ecu. And wired the last 2 cylinders into a hot so it would fire . But now 2 of the cylinders i belive 7 and 8 are loading up any suggestions to get past this ?

you used relays on injectors?

How about a proper harness?

Relays to control injectors... wow.

Ok lt1 has 2 connectors going to the body harness and the 3.4 has 1. So i took the 2 combined it into 1 matched all the wires , for the 2nd connector had 1 wire in there that i found on all data to control the secondary injectors so i just added a power to kick them on to start the vehicle.

electrically what you did is wrong. relays are far too sloppy timing wise


You should have made the lt1 harness more or less stand alone

What year PCM is it?

94 pcm with a 95 ecm.

And sorry for the typo we never tied it into a relay thought we did. My buddy did the wiring not me.

Hmn, what?

do you mean BCM? you keep talking body harness

the power control module is stock form the 94 3.4. Then we used a 5.7 95 Engine Control Module.

So how did you do all the pin outs?

All Data.

i think that your friend should step away from the wires.

did he try to integrate the two?


All data? you mean he looked at a diagram & started cutting & splicing?

So you are using a LT1 PCM and parts of a 3.4 harness?

Why the relays?

Becuase have you EVER tried to replace a WHOLE BODY HARNESS. Its Probable atleast a 15 hr plus job. Now dont get me wrong i have the 5.7 harnes and worse case scenario i will put in the lt1 body harness. But im trying to see if theres ANY Possible WAY wiring wise that DONT HAVE TO DO THAT!

I am so confused.

You don't need to replace a body harness. I guess I would have made the LT1 harness basically a stand alone harness. what does the body harness need to know, rpm? gotta be a way around that.


And yeah, I've rewired some cars.

the harnesses on f-bodies really arent that hard to do... its a big job... but... its better to do things right then Frankenstein up your car... i suggest you start ripping stuff apart and change the harnesses properly... way to much important stuff running to and from those harnesses to screw it up... just my .02 take it for what its worth... with that said... what is it with people trying to save a minute and doing stuff 1/2 asked... first the guy cutting holes in his floor and now this... good luck either way man

Ok Im going this explain this thoroughly and when you understand this Say OK.

Ok LT1 5.7 engine has 2 body harness conectors.

A Firebird 3.4 Has Has 1 Conector to body and Engine.

I took the 5.7 engine Harness Plugged Everything In But the Car would not start. So I recently found out , that it was not firing on 2 injectors becuase it was a 6 cylinder. So I went to All Data , I traced the wire diagram from the connectors , I found my main Power wire for the other 2 injectors. And I ran it into 1 connector. The car started started ran evenly but now when it gets up tempeature the cylinders load up. There were no cutting or splicing , I popped 2 wires out that was for a serial wire and the other injecor and pinned it into the other connector.