[Qwisler135]

I have a 2012 bmw 328i. The other day, the car started misfiring in cylinder 2 and 4 and was flashing the engine light, white smoke coming out the exhaust. The spark plugs were black, from fuel, we replaced them and deactivated the bm3 and jb4. It now seems like the car is building pressure in the valve cover. And still running rough. Does anyone know what the problem might be?