[Pohsib]

2006 BMW 330i 6MT w Sport Package ~200K miles

After a slight bit of what might be consider "spirited" driving (I don't think I exceeded 5K rpms accelerating or downshifting) my car started a terrible flapping sound. It doesn't do it while idling but it does run rough like a missing cylinder - the whole front end of the car vibrates. Also, when I try to drive and it starts that terrible flappy sound, I can't pull over and get out of the car fast enough to see it there's anything going on in the engine bay. The "flapping" doesn't stop the instant I take it out of gear and pull over.

I had just replaced the radiator with an all aluminum one, a few coolant hoses, the belt, and the tensioner. I had driven the car about 40 miles that day and it ran beautifully. The "flapping" event started that evening after about five minutes of driving and one minute of that spirited driving (if it can be called that.) Since I had purchased new coils and spark plugs, I went ahead changed them out. That did not fix the problem.

I started a list of possible problems in the order that I think could possibly be:

Broken DISA valve
Faulty eccentric shaft sensor
Faulty valvetronic camshaft adjusting unit
Fuel injector issue

Less likely
Timing chain and /or tensioner?

I didn't notice any fuel smell or white smoke. However, I wasn't looking for that during the brief the time I had the engine on. There isn't a metallic or clanging sound from the engine so I'm told that it's unlikely that I broken something in there. There wasn't any oil on the end of the plugs when I pulled them (there was oil around the top of plugs four and five but I'm pretty sure that's because I need to change my valve cover gasket.


How can I sort through the list of possible issues?

I should add too that I have not ruled out possible fuel issues or visually verified the engine mounts. I think those two are unlikely because I changed the engine mounts last year. I get 93 No ethanol gasoline at the same gas station all the time and due to the timing (after "spirited" driving) of the issue I don't think the gasoline is the issue.