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Old 01-17-2018, 07:41 PM   #1
Bladeboy1998
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Join Date: Nov 2014
Location: Toledo Ohio
Posts: 520
2003 2500hd 6.0 odd vacuum leak issue

Alright guys, I've got a weird one for you. I have a miss fire on cylinder 1, 3, 6, and 8, 8 being the worst. Fuel trims on bank 2 are wayyy rich, almost acts like a vacuum leak, has the high idle, misfire, and fuel trims way off. Propane tested around the intake, no leaks that I can find. So I move on to the smoke machine, still no external leaks. (I'm putting the smoke machine nozzle into the fuel pressure reg vacuum line.) I pulled the pcv hose off, and pluged the intake side. It came out of the valve cover with pressure. Pulled the oil cap, same there.

I have a vacuum leak internally from what I can see. So I pulled the valve cover thinking it may be valve stem seals cause the intake valve could be closed and leaking up through into the valve cover. Well turns out its coming from the pushrod galleys. My next thought was rings, did a compression test on bank 2 side, all were at 130 psi +- 3 pounds. Compression is perfect.

Got a new plug for cyl 8 cause I broke it anyways, and moved the coil from cyl 2 to cyl 8, and the misfire stayed on 8.

I feel like I'm chasing 2 different problems, but I'm lost. It's killing my fuel economy too
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