1bad87ss

I posted in Pam thread previous but have had a false diagnose. I have a 09 g8 gt. Camped and stalled. Car started missing a few weeks ago. One day I tore into it doing all of the obvious. I changed plugs coils and still missed. Bench tested injector and reinstalled. Still fouled plug. Swapped injectors and coils to other cylinders. Still fouled. Fouled as in black but not wet. Like it had fire and fuel just not enough. Then I went to compression test. All tested at time at 180psi. So I was stumped. I believe I had a warm engine at time and that was a false reading or something. Not sure why. Well the car sat for a while and I finally got back around to rerunning some test. Did a cold engine compression rest and #1 had 135 and others at 180. Now getting somewhere. Put a couple squirts of oil in cylinder and it went to just over 150. Pulled head off and took to machine shop. Everything checked out. Pulled vac on all 4 and no issues. Just pulled Bolton end and took out number one piston and there is nothing obvious wrong besides a couple very very minor scuff on the exterior side of the cylinder wall. Could this really cause this. I am taking to taking to machine shop in the am for him to look at but highly doubt that's the issue. What else could it possibly be. Head gasket didn't show any obvious signs either

Really stumped on this.

Thanks for any input .

LLLosingit

iTrader: (4)

First thing I would recommend is that the next time something happens slow down before you go tearing things apart, It's easier to diagnose a problem before tearing down. A compression test should be done with the engine at operating temperature with all plugs pulled and throttle blades open. A better way to diagnose a problem like that is a leak down test. A compression test will only tell you that you are losing compression, A leak down test will tell you where you are losing it.

Fouled black is most likely oil fouled, Oil mixed with fuel and air is much harder to burn than just fuel/air so that could be why the miss didn't go away. If the head checked out it's probably had a ring sealing problem (leak down test would have pointed this out).
Ring seal problem could be caused by several factors. Worn rings, Carbon on rings/ring lands among other possibilities.