2007 Tahoe 5.3. Misfire

[jacobsprad]

This is a flex fuel with afm. Codes are showing misfire 1 and 7 stabilatrac and abs etc. There has never been an issue, with either. I was at 90 cruise controlled, after an hour. It started running rough and all those lights came on the dash.

[CamGTP]

Both cylinder 1 and cylinder 7 are AFM cylinders. Possible that a lifter failed on one or both cylinders.

 

Pull the valve cover to see what the rocker arms are doing. If one is loose because the lifter collapsed then you found your problem. Sometimes the lifter will stick in the bore and that rocker arm/valve won't move with the others when you crank the engine over.