Intermittent wastegate rattle after 'spirited' drives

[NYHoustonman]

Hi all,

Twice this year so far, my N54 (Dinan stage 1 - very mild tune) has developed a very noticeable wastegate rattle under on lift off and under throttle. Accompanying this is a rough/garbled exhaust note.

The first time this happened was about a month ago. I went for a mountain drive and everything was fine. After parking the car for about an hour, I started it back up and the symptoms mentioned above showed themselves for the first time. After parking again and coming back an hour and a half or so later, the problem was gone. I calmed down and thought nothing of it.

This past Sunday, I went for another mountain drive and, under similar circumstances, the symptoms reappeared. They didn't go away this time until yesterday afternoon (coincidentally after an oil and brake fluid change).

I treat this car well, I think. I never ask much of it until it's warmed up, and I give it plenty of time to cool down via gentle driving each time I thrash it (once every two weeks or so). No codes have been thrown. I know there are a few possible causes for wastegate rattle, but as I understand it the rattle is usually present only after cold starts, or always present, etc. I haven't found anybody describing this mode of failure.

Does anyone have any ideas as to where to start troubleshooting?

[Dackelone]

defective wastegates...

[NYHoustonman]

I'm aware of the deficiency and know I'm covered till 8 years/82k miles, but I was hoping for some anecdotal evidence . The problem I have now is that the symptoms are completely gone - no wastegate rattle, no perceptible loss of power. When I bring the car in to BMW there's no guarantee that they'll find anything (or even agree to look at it without a code to guide them).

[Dackelone]

Try this...