[rocket335is]

greetings, I have been experiencing this issue for 5 months already and wasn’t able to fix it. I got 335is with N54 engine. Car is jerking under acceleration, barely going with 30mph and weird roaring noise coming from intake/tb area, and charge pipe is moving(as if inflating)when flooring. Also took off intake manifold and it is firing outside the engine, I serviced the engine, thought timing was off, changed chain, valve seals and both camshaft with ledges, still the same. Compression is 180psi in all cylinders, used Boroscope and investigated cylinders, everything is perfect, also smoke tested couple of times, no leaks. Changed spark plugs, coils. Changed DME MSD81 2 times, always the same. Valves are not bent, timing is good. When u are revving in neutral, 3-4 thousand rpm, u can hear roaring from intake. Main thing is engine is backfiring when I took off intake, which means that intake valves are open during combustion. Any ideas, it drives me crazy already. If that helps car has DCT transmission. What is more important, only misfire codes, nothing informative. Thank u.

[suspect]

Originally Posted by rocket335is

greetings, I have been experiencing this issue for 5 months already and wasn’t able to fix it. I got 335is with N54 engine. Car is jerking under acceleration, barely going with 30mph and weird roaring noise coming from intake/tb area, and charge pipe is moving(as if inflating)when flooring. Also took off intake manifold and it is firing outside the engine, I serviced the engine, thought timing was off, changed chain, valve seals and both camshaft with ledges, still the same. Compression is 180psi in all cylinders, used Boroscope and investigated cylinders, everything is perfect, also smoke tested couple of times, no leaks. Changed spark plugs, coils. Changed DME MSD81 2 times, always the same. Valves are not bent, timing is good. When u are revving in neutral, 3-4 thousand rpm, u can hear roaring from intake. Main thing is engine is backfiring when I took off intake, which means that intake valves are open during combustion. Any ideas, it drives me crazy already. If that helps car has DCT transmission. What is more important, only misfire codes, nothing informative. Thank u.

If you have made sure timing is the correct the only other thing I can think of is somehow the VANOS system.

[rocket335is]

Is there a possibility, that it’s an electricity related thing, grounds? Since I have already swapped 2 DMEs, and they worked the same

[whyzee125]

I unfortunately don't have any advice here but I'd love to see a video for curiosities sake. Maybe it would help another member point you in the right direction too.

[rocket335is]

I will put valve cover back on, I checked timing 2 times already, and will take a video and post some log 0-30 mph😅.