2009 Cooper S 6-speed w/ 93k KMs (57k miles).

Recently I've been experiencing very slight flat spots in the RPM curve after a cold start and during the warm up period, usually below 2k or 3k RPMs and mostly noticeable with moderate acceleration in 2nd, 3rd and 4th. There doesn't seem to be an issue when the motor is up to normal operating temperature.

Secondly, around the same time I noticed this, upon start up, it grumbles around 9k RPMs instead of the usual fluctuation to a higher RPM before settling at a lower RPM.

Thirdly, higher end RPMs (4k+) feel a little flat, noticeable in 1st, 2nd and 3rd. It's hard to tell for sure at the minute with our slick roads.

I'm concerned as I have a 1k mile trip coming up over Christmas and I'm wondering if this may or may not be early symptoms of carbon build up?

No codes. The MINI runs fine otherwise. No spluttering or hesitation. I've only owned it for a year and a half and to my knowledge it's never had a HPFP or walnut blasting. I have a very short in-city commute but tend to open it up on the weekends.

 

I don't know for sure if it carbon buildup or not, but I know that our 09 it started feeling weak and had a rough idle, no warning lights. So, I purchased some seafoam from the local auto store and ran it through the PCV hose on the valve cover and it worked wonders. It might just breathe a little life back into your MINI.

If you do not know about seafoam:
It is a liquid that you can suck into the intake tract through the vacuum pressure from the PCV hose on the top of the valve cover. Once you suck in about half the bottle, you shut the car off and let it sit. The seafoam works to break down any deposits on the valves. You start the car and give it some moderate revs until the white smoke clears from the exhaust. In theory it should burn off any carbon from the valves. In my use, it has worked very well but might take more than one use for perfect results.

Good luck!!