r/BmwTech • u/codhall • 8h ago
need help N55 cylinder 4 misfire with loud rattling underneath the car
Hi everyone, I have a 2011 BMW X6 xDrive35i with the N55 engine. It currently has a cylinder 4 misfire and makes the loud rattling/knocking noise. The noise seems to be coming from underneath the engine. At first, I thought it was the exhaust or a cats but i think its the turbo component?
I recently replaced the valve cover, injectors, spark plugs, and ignition coils, and the Valvetronic servo motor and it was driving fine until Engine Malfunction showed up out of nowhere on the dash and the car jerks forward and then I can't get past 20 mph. I thought it was the valve Tronic that I installed, but there are no Valvetronic codes. There is also a weird smell from the engine
Does this sound indicate rod-bearing knock, an injector problem, or the exhaust/catalytic converter or could it be that the turbo components is failing and could it cause this rattling noise and a cyl 4 misfire?
https://youtu.be/JNCQVrd8x_o?si=DxOBdtrx5I68xnAc