Need help finding misfire! Possible corruption of tune.

[Josiah0303]

Hi so I would greatly appreciate some help figuring out what?s going on with my car.

So, there is a misfire on cylinders 4, 6 and 8. The spark is weak on those cylinders and a noid light shows every injector is seeing a signal from the PCM. So far I have replaced the plugs, wires, ignition coils, a few injectors and made no change. I thought it could be the PCM so I used the VCM suite to load my tune onto a new computer and the misfires followed it.

My car uses the Turbonetics T76 turbo kit as well as a mild cam good for boost and all the supporting mods. The car was tuned on e85 by Levin Motorsports in FL but it doesn?t use a flex fuel sensor. So my problem started after I couldn?t get to e85 and ran 93 through it. It starting misfiring and flashing the stabilitrac message, so I reset the computer by pulling the neg battery terminal. That temporarily made it run well but then within a week, resetting the computer made no change.

Can anyone please tell me if it?s possible that I corrupted the tune on the car?? Because I am at my wit?s end and don?t trust any shop to work on the car aside from the shop that did the tune and I live 3 states away from them.

[5FDP]

How's the wiring?

Is the coil pack harness pins all in there tight? Have you checked the grounds on the cylinder head and transmission?

[Josiah0303]

Yes the harness is intact still. I went through every wire I could reach to look for shorts but didn’t find any. The main grounds from head to body and frame to motor are okay, I didn’t find any frayed wires anywhere yet.

I should have added that the car is a 2010 Camaro SS with the 6.2L and manual 6 speed. Also, I did not find any vacuum leaks anywhere and I also did not find any broken valve springs, the car has comp dual beehive type springs.