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Misfire on a Hemi
Posted to Technical Discussion Forum on 8/23/2017 8 Replies

Hemi came in yesterday with an intermittent misfire on cylinder 8- checked the misfire counter and could watch misfires happening on the right bank consistently. Customer informed me the truck had just had head gaskets at another shop in town. I thought maybe the head was leaking and checked the coolant for exhaust gases, but got nothing. Pulled a plug, and it was heavily fouled and had carbon tracking up the insulator. Replaced plugs, wires, and COP boots thinking that was the problem. Nope- still has a light misfire. 90% of the misfires are coming from cyl#6, with a few randoms from 1,2,4, and 8. I swapped cyl #6 coil with cyl #3, and cyl#6 still has a mis.

Pulled #6 plug and found it was fairly oil soaked, after running for roughly ~45 minutes. Thinking this may be related. Are these hemis known to use oil? Valve seal? Intake manifold?

J.B. Chapman
Owner/Shop Foreman
Chapman's Automotive
Craig, Colorado, USA

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car Vehicle Data

2005 Dodge Ram 1500 ST 5.7L

VIN 1D7HU18D45
Engine5.7 L
Trans5-speed Automatic (Electronic)