328i Strange noise from under drivers seat
Ok I have a 2011 328i with what sounded like electrical static coming from under the drivers seat. I thought it was my amp or head unit going out. Went to the stealer they said nothing wrong. I guess they meant nothing wrong as in the amp and head unit were ok. However I guess they didn't take the time to use their ears and hear the sound. Anyways I went home put the car on ramps and crawled under the car and removed one of the splash shields and could hear the noise right away. When I grabbed the exhaust bracket the noise would stop. I checked all the bolts they where tight. Turns out there was one loose bolt on the transmission brace. The washer under the bolt was vibrating and causing a high pitch sound that would vary with engine rpms like a electrical noise through a speaker. I tightened that bolt and my problem was solved. I hope this may help someone with a similar problem.