Please Help, LS2 Cylinder 4,6 misfire Mechanic Can't Figure Out
08-07-2018, 09:29 AM
#1
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Please Help, LS2 Cylinder 4,6 misfire Mechanic Can't Figure Out Please help! neither me nor my mechanic can't figure this out and I may have to give up my 2006 GTO, 6 speed.
Issue: "Random misfire" flashing code, cylinders 4 and 6, code indicating lean in one bank, rich in the other.
Trouble shooting thus far:
- New Plugs
- New Wires
- Coil Swap
- Injector swap
- Compression test
- Running compression test
- Manifold leak down test
- Remove cats to check for back pressure
- MAF sensor is clean
Mechanic says problem could be worn cam lobe. Quoted me 20 hours labor to change cam. Not sure whether this will solve the problem. There are no codes indicating crank position or cam position sensor issues.
I'm so frustrated. I just spent 600 bucks on a steering rack. I currently have a low catalyst efficiency code and have catted mids. (not installed) and a starter (not installed) Already replaced clutch, rebuilt tranny, water pump, new suspension, brand new tires, rear main seal, radiator hoses, and other stuff and I may have to just walk away from the car. UGH.
Can anyone with any help?
The only mod is vara ram cold air intake.
Issue: "Random misfire" flashing code, cylinders 4 and 6, code indicating lean in one bank, rich in the other.
Trouble shooting thus far:
- New Plugs
- New Wires
- Coil Swap
- Injector swap
- Compression test
- Running compression test
- Manifold leak down test
- Remove cats to check for back pressure
- MAF sensor is clean
Mechanic says problem could be worn cam lobe. Quoted me 20 hours labor to change cam. Not sure whether this will solve the problem. There are no codes indicating crank position or cam position sensor issues.
I'm so frustrated. I just spent 600 bucks on a steering rack. I currently have a low catalyst efficiency code and have catted mids. (not installed) and a starter (not installed) Already replaced clutch, rebuilt tranny, water pump, new suspension, brand new tires, rear main seal, radiator hoses, and other stuff and I may have to just walk away from the car. UGH.
Can anyone with any help?
The only mod is vara ram cold air intake.
08-07-2018, 01:14 PM
#2
I don't see where you verified the injector on 4 or 6 was firing other than swapping injectors. Put a noid light on the injector harness and make sure the harness is actually firing that injector. Also you swapped plugs, wires, and coils, but did you verify you have spark on those cylinders? Swapping parts in hopes of fixing stuff isn't a good way to troubleshoot. Did you do a leakdown test, not just a compression test? Itll tell you if you have a leaking valve or cracked piston ringland.
08-23-2018, 11:26 PM
#5
Good suggestions already on verifying the #4 and #6 injectors are receiving signals. You never mentioned the results of the compression and leak down tests though...? Adjacent cylinder random misfires makes me think possible head gasket failure between the 2 cylinders. Compression test fail on #4 and 6 would narrow it down and the leak down test would confirm if that were the case. I’ve seen similar failures and you don’t always get the classic coolant in oil clue, only pressure loss between the cylinders
10-21-2023, 06:47 AM
#7
My reading comprehension sometimes fails me, that said....
Since the code was present when you bought it, your changing the cam is not what is causing the code. It could still be the crank sensor though since we don't know what the seller did previously. From what you say about the seller, we can assume that he/she was not totally up front.
Since the code was present when you bought it, your changing the cam is not what is causing the code. It could still be the crank sensor though since we don't know what the seller did previously. From what you say about the seller, we can assume that he/she was not totally up front.
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10-21-2023, 10:55 AM
#8
TECH Senior Member
Meanwhile, 5 years lateur.....
