Q7 Q7 Help

[Roddy269]

I have a 2006 Q7 4.2 FSI and its started misfiring and the engine light came on. It gave me codes for misfire on all cylinders. The car is at 122k but the engine was replaced at 76k. Compression is also jumping all over the place.
Codes showing: P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308
Does anyone have any experience with these engines?

 

[Roddy269]

Update. Long over due...

Turned out that the intake manifold plastic flags had disintegrated and a bit of plastic was actually wedged under the valve, not allowing it to move and causing a misfire.
This also caused the hydraulic lifter to pop out of place, had I not removed the rocker cover. I'd have been screwed.

Luckily the lifter was put back and the plastic was removed. Inspected the valves and piston and saw nothing wrong. Compression tested fine. Manifold was put on with all new gaskets. Took lots of time but not much expense. Did a service and repaired the misfire for around £200 in parts and my own time.