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Discussion Starter · #1 · (Edited)
Hi guys new to the forum.
I'm working on a 2015 2.0 tfsi A5 S line. customer came in for oil consumption and cylinder 3 misfire. Diagnosed it to be bad pistons to cause the oil consumption and burnt valve for the misfire. When the engine was disassembled we found the burnt cylinder 3 exhaust valve and damaged seat.
I've sent the head out to a machine shop to replace the valve seat. I replaced all exhaust and intake valves and lapped them. Installed the head, changed the spark plugs, injectors, ignition coils, vvt solenoid and actuator, pistons, timing chain and tensioner. (ALL GERMAN OEM EQUIVALENT PARTS USED)
I noticed the repaired exhaust valve #4 in picture below is sitting a bit lower than the rest . will this cause a problem now with the valve sitting deeper in the head, which puts the valve closer to the camshaft. there is no valve lash adjustment as these are hydraulic lifters. and once the valve cover goes on to secure the camshafts there is no way to check clearance. will the hydraulic lifter compensate for the deeper sitting valve?
I still have a cylinder 3 misfire. when i have the scan tool open, under misfire counter, cylinder 3 only misfires the 1st minute on cold start up. once the engine is warm the misfire goes away and drives like normal.
the high pressure fuel pump has 580 psi. leak down test is at 35% leakage steady though out all cylinders. compression test is steady at 200 psi through all cylinders.

Any idea on what it can be?
Possibly bad valve seat installation due to valve sitting too low ?

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