Got the P0302 code, engine is clearly running on three cylinders, very rough idle and little power. checked the plugs and they're all in good shape (replaced all four about 6000 miles ago), but #2 plug was still wet. Threw on a new coil on #2 plug, but still misfired.

Injector stuck open? Carbon build up? 02 sensor?

 

Bet the carbon is built up enough to be causing a valve issue...

 

What engine/car/chassis is this?

 

Its an '08 R56 type S hatchback, N14 engine (if i remember correctly), no mods or anything, bone stock.

I swapped plugs from cyl 1 and 2, cyl 2 is now dry and looks pretty covered in carbon, and cyl 1 plug is now wet. Might have multiple issues, bad plug not sparking/burning fuel, and valve issue on cyl 2. A shop recently told me I've got exhaust making its way into the coolant system, so I've got a leak somewhere, and I'm sure thats not helping either.

If its not just a plug, this is gonna be expensive.