Now and again I get some knocking from the engine on my 320i E92. Its happened twice now but then goes away for a while and you can't make it do it again. The engine sounds rough when its happening but I've noticed no lack in power or performance or drop (or rise) in fuel economy. It seems to be driving fine and doing OK so I don't get where this noise is coming from (see video). It will go away now for a while and come back at some random point in the future. Started it today on the drive and warmed it for 15 minutes or so, revving it to get the heat through it. Couldn't make it do it!
Any help appreciated
