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Random misfire light acceleration on the interstate.

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Vehicle came in and i replaced the motor mounts due to them leaking fluid (fluid filled mounts). 

test drove the vehicle and felt a slight surge on the interstate under light throttle. check with scanner and almost all the cylinders (on both banks) had misfire counts. its just odd because i can get it to misfire under load or power braking it. (maybe 1 or 2 random counts when doing that but not as bad as under acceleration) 

Did find some issue with the torque converters. vehicle has about 60k on the motor thinking i should start with some spark plugs. Anyone ran into this issue? 

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  • 2 months later...

Mode 6 misfires or actual stored DTCs?


Engines never going to run a drive cycle without a some sort of count (at least that I have yet ever to come across).


As long as the counts are uniform across the cylinders and they are hard stored or excessive, I wouldn't worry about it.


For example: typical 35miles drive cycle to work will results in misfire counts on our 19 Tahoe upwards of 10-15 across the cylinders (closer to 10 in 1-6 and 8, my cylinder 7 typically has a 50% higher count which I'm keeping an eye on as it's an AFM cylinder). We have 69k on our 5.3 and I already swapped out plugs around 50k IIRC.


You could try running some valve cleaner (seafoam, BG, etc) to try cleaning the valves and see if that helps. Plugs are easy and cheap, so another thing that wouldn't necessarily hurt to do of you wanted.

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  • 2 weeks later...

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