My 2011 335i N55 has had a very slight and intermittent knock/tapping noise which can be heard at idle only. Pushing hard or with high rpm, no issues. I recorded a video where i taped under the car and the noise was much more pronounced [bottom end, driver side area]. Besides occasional surging idle, and the noise specifically, no real issues. I have it in my head that if it goes, it goes and just replace it through my aftermarket warranty, hopefully. But im curious by nature so any ideas?
The vehicle has 79,000 miles right now and i bought it with 63k. The noise became much louder right after oil change with fresh oil, then slowly leveled to the occasional idle knocking.
It does not sound like injector noise, nor is the sound coming from that area. I also sent oil to Blackstone Labs, adking about the problem specifically and they said there is no metal shavings.