Hey, there.

2012 Mini Countryman S, 6-speed.

Wondering if anyone has a clue about what could be causing this. It only happens under full throttle/very near full throttle. It only happens between 3000 and 5000 RPMs. It feels like a miss in one of the cylinders. It happens 1 - 3 times very quickly in each gear, then stops (or I upshift). I get a pop and burble from the exhaust at the same time, similar to when I downshift. No smoke, no warning lights. Though I haven't yet hooked it up to a scanner to see if there are any codes that just weren't severe enough to trip a light.

Things off the top of my head I could see it being, no particular order:

1. Dirty fuel filter that chokes under high demand
2. Spark plug that is fouled and doesn't burn correctly under high load
3. Fuel injector started to get clogged that doesn't spray the full amount it should under high load.
4. Waste gate is activating early, and dumping boost.
5. Some issue with a cylinder, maybe compression or valve issue.

One guy I read about had a very similar scenario but on an '02 Cooper. Ended up a piston head had a chip or hole or something. Had to have all the piston heads replace, and the top end rebuilt.