2013 BMW 335i N55 - Multiple Misfires and P0300, P0301, P0306

Question

My F30 is throwing codes for random misfires and specific misfires on cylinders 1 and 6. It happens mostly when the engine is cold or when I'm merging onto the highway and really bury the pedal. If I drive like a grandma, it stays smooth, but any boost causes a 'Drivetrain Malfunction' warning on the iDrive.

I pulled the plugs and they looked a bit dark but not wet. I'm afraid it might be the HPFP starting to go since these N55s are known for it, but I don't have any fuel pressure codes yet.

HighwayHelen · Answer

Check your intake valves for carbon buildup. At 80k+ miles, the N55 gets pretty bad since it's direct injection. If the valves are coated in gunk, you'll get turbulent airflow at idle and under load, causing those P0300 codes.

ShopBossMike · Answer

✅ Confirmed fix: This turned out to be two failing Bosch ignition coils that only broke down under high load/high heat. Even though I swapped 1 and 2, the random P0300 kept coming back. Replaced all 6 coils with the updated Delphi units (the ones with the metal sleeves) and the misfire is completely gone.

WeldShopWanda · Answer

Check the gap on your plugs. If you're running any kind of tune, the stock gap is too wide for high boost. Drop them down to .022 and see if the blowout stops.

2013 BMW 335i N55 - Multiple Misfires and P0300, P0301, P0306

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