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Burnt valves on 4-6 cyl, but lean mixture on all cylinders?
Engine: n52b25, huge problems in the lower rpms
Okay, so - Dry + Wet compression test results:
Dry compression test - between 12.5 and 13 bar across the board (180-190psi) which is obviously pretty low, piston rings are worn for sure.
Wet compression test is where it gets interesting - cyl 1-3: 17 bar (250psi), so obviously the few drops of oil help fill the gaps caused by the worn piston rings, but cyl 4-6 with a few drops of oil - between 13.5 and 14.5 (190-210psi), burnt valves seem to be the apparent cause. So I would understand a lean condition on bank 2 (cylinders 4-6), but why would bank 1 (cylinders 1-3) run lean?
TLDR:: Why would the car be throwing Lean mixture codes on ALL cylinders (both banks), if 1-3 only have worn piston rings and valves seem to be in order? Or would the huge compression loss from the piston ring wear also make it burn lean?
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