|
I had such a very annoying sound in my exhaust of my 1998 Volvo S40 T4. It was clearly a phenomon of resonance, since it popped up at certain (low) rpm's only.
They told me then it was the catalyst in the exhaust coming in contact with the outer shell or a piece of the catalyst substrate breaking off and getting somewhere in my exhaust. They never cured it. I hope it's not such an ugly bug they can't find!
Since your car is brand new, insist them on getting it solved. I would be pissed when I had an M135i sounding like a trabant falling to pieces! I assume BMW will understand it's unacceptable.
|