Bad PCM or Harness??? LT1 Car
09-05-2010, 04:22 PM
#1
Bad PCM or Harness??? LT1 Car Ok when I went to hook my harness back up in the car I accidentally hooked the Ground that goes by the knock sensor to the hot side of the starter....hooked the battery up and got a smoke show on the passenger side... Unhooked the battery and figured out what happened... The burnt wire went up into the harness I chased in and re spliced in a good section for the ground.
Car started no problem however it has had a high rpm miss now since the new motor went in.
Car tuned out fine on the dyno with the exception that it wouldn't turn past 5800 because it would start missing...
I have redone all the fuel, ignition and valve train....
Is it possible that a bad PCM or Harness could cause this type of problem??
Thanks
Matt
Car started no problem however it has had a high rpm miss now since the new motor went in.
Car tuned out fine on the dyno with the exception that it wouldn't turn past 5800 because it would start missing...
I have redone all the fuel, ignition and valve train....
Is it possible that a bad PCM or Harness could cause this type of problem??
Thanks
Matt
09-05-2010, 10:33 PM
#2
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Sounds like the opti to me. I've seen a few bad ones recently so it tends to be the first place I look now.
The last bad one that I saw had a miss @ 5000rpm. The opti was replaced and the misfire remained.
It wasn't until the car was converted to COP and LS engine management that the misfire went away.
The last bad one that I saw had a miss @ 5000rpm. The opti was replaced and the misfire remained.
It wasn't until the car was converted to COP and LS engine management that the misfire went away.
09-07-2010, 09:42 AM
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Check out eficonnection.com. You could spend anywhere between $1000 and $1500 depending on how much you source on your own. You can pick up some truck coils and a 0411 PCM from the junkyard. If you aren't afraid of some wiring, you can re-pin your harness-PCM by yourself and save some $.
The other nice thing about it is the availability of superior tuning/scanning software (ie. HP Tuners and EFI Live).
Have you tried replacing the opti harness yet? I had one car that this cured a high RPM misfire on.
There was never a smoking gun found on the last LS/COP converted car that I tuned. We had an o-scope hooked up to every part of the ign system. We replaced the Opti, ICM, and multiple harnesses and didn't have any luck. We had completely ruled out anything mechanical or fuel related. So, we swapped everything over to LS/COP and the problem went away.
The other nice thing about it is the availability of superior tuning/scanning software (ie. HP Tuners and EFI Live).
Have you tried replacing the opti harness yet? I had one car that this cured a high RPM misfire on.
There was never a smoking gun found on the last LS/COP converted car that I tuned. We had an o-scope hooked up to every part of the ign system. We replaced the Opti, ICM, and multiple harnesses and didn't have any luck. We had completely ruled out anything mechanical or fuel related. So, we swapped everything over to LS/COP and the problem went away.
