CalSpeedPerformance

iTrader: (64)

I just started up a new LS1 conversion in a 94 formula firebird... Im using a Wait4MePerformance 99 conversion engine harness

It fired right up and i noticed a misfire in the car that seemed pretty apparent.

HPtuners shows no codes related to the misfire, only that it has a 100% misfire on cylinder 4, 8 and 5. It starts up no problem and idles with the mis, the miss doesnt go away when you bring the rpm's up.

I checked for fuel and has fuel on all cylinders. (checked with a noid, and swapped all injectors out).

Then I checked for spark and it has absolutely no spark coming out of 4,8,5 coils.

So its spark. I then verified it has all the grounds, even moved them to different bolt on head. Then I added extra ground wire from battery to frame and battery to engine. I then swapped the computer out with another fbody pcm with the tune loaded into it. I then swapped out the coil packs & the coil pack harness with another set. VATS is turned off fully...theres nothing in the tune that could be causing this.


Any ideas of what could cause 3 dead cylidners with no spark from the coils?

Im going to swap cam/crank sensors tomorrow and do a crank relearn. Im to the point im going to swap the wiring harness if i have to

DaddySS

It would seem that you're on the right track with the crank relearn, since it's strange to have no spark on 2 cylinders on one bank and one on the other.

CalSpeedPerformance

iTrader: (64)

I dont know what year the harness is from ( I believe its a 99). Im going to verify tomorrow. Only other thought is that its a 98 harness with a 99 computer. But I cant picture that even starting up would it?
The PCM is for sure a 99 (Ive tried two 99 computers).

CalSpeedPerformance

iTrader: (64)

I tried a 98 computer with vats turned off in the car today and it wouldnt start at all....

Also changed crank, cam sensor today..no change. Ordered a painless wiring harness, going to swap it in and see if it changes.

wait4me

iTrader: (10)

Did you try moving the coils to different sides and see if it follows? Maybe you have bad wiring on the coils or just bad coils?

wait4me

iTrader: (10)

Also do the pink wires on the coils all have 12volt when you have the engine running?

CalSpeedPerformance

iTrader: (64)

I swapped out the coilpacks with harnesses on both sides... no change

CalSpeedPerformance

iTrader: (64)

I'll check that today...thanks for the tip.

CalSpeedPerformance

iTrader: (64)

I fixed it.....finally after changing everything possible, I tried something i've never needed to use in 20+ ls1 swaps or 100's of tunes..

I did a case/crank learn on it and it completely fixed the problem. Runs great

Frost

iTrader: (45)

did it set a dtc for that or did you have it disabled?