I've had my 07 Cooper S since APR this year and have been having some problems with it ever since then. My car had this intermittent acceleration issue, which I was pretty sure was carbon related. Did some minor fixes to it, but recently the car has been misbehaving when accelerating, usually in third/fourth gear.
The best way to describe it is a pinging/sparking noise coming from the drivers side of the engine bay, and at the same time as the noise the car loses all acceleration, before kicking back in again. The car has no fault codes or lights on, but it has also done it before when accelerating gently, although not to the same extent. Anyone else experienced this before?