Anyone have misfires after unsticking an AFM style lifter?

slowfive0 · 2021-12-14T01:24:58.000Z

I have a 2015 6.2 (L86) engine that had a stuck #7 intake lifter. I was able to unstick the lifter using the special tool, but now I have a small miss that counts up only at idle on #7. Fuel trims are negative, but very low and are both very close to each other at all rpms EXCEPT idle. At idle Bank1 is skewed negative by 7 points (LTFT1: -10 vs LTFT2: -3). I replaced that injector and made no change. All the injector seals were intact. NOTE: Misfires only count up on #7 at idle or at extremely low rpms. It never sets any misfire codes, but you can feel the roughness in the steering wheel and it doesn't idle cleanly. It does set fuel trim imbalance codes. Sometimes just bank 1, sometimes both banks; i.e. P219a/P219b. I checked compression and #7 had 230psi & #5 had 260psi. I put a couple of squirts of oil into cylinder #7 and the reading went up to 260psi which would point towards a ring issue. I was leaning towards a damaged camshaft issue, but am having hell trying to get my dial indicator setup to work (brake booster in the way) so I can't 100% verify the lift vs a k/g cylinder. For what its worth, I didn't see the dial indicator needle jump when checking the lift over the nose of the cam (which might indicate damage). Lift reading was questionable though as mentioned due to the booster. Maybe the lifter or rocker arm (bearings) are damaged and have some play in it or something weird like that but I would expect misfires at all rpms......? Maybe not....? The low compression seems to point to a camshaft problem (truck was great before), but the compression jumping up with the oil test has me perplexed.......Appreciate any thoughts/suggestions before I dive into this pos ;-) Thank you.

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