My 2009 MCS has a great MINI service history until I bought it about 2 years ago. The car just went above 130k miles, the last 40k or so I have owned it and done all the service myself. Lately, the car has developed a bit of a stumble / rough idle. It might be a miss but I'm not 100%. This happens most of the time at idle, the few times it doesn't happen I can't really explain yet. The car pulls great under throttle.

I have been regular with the oil. I have a craven dipstick to help with that. I have not done any ignition work nor do I know if the car has had any carbon deposits removed.

It just bought an F56 and I'm planning to sell this car. I would like to get her purring smooth for the next owner, but I would also like to avoid anything too major.

Anything obvious stand out that might cause this?

 

Given the mileage, wondering if one of the coils is going bad - do you experience rough idle under wet conditions (like after it rains/snow) but not under dry conditions? Any CEL or DTC codes that is indicating a misfire in any of the cylinders?

 

It doesn't really rain or snow too much here in California so I can't honestly say about how it does in the rain. The issue happens when it is dry. Also, there is nothing set on the dash for CEL or DTC but I haven't pulled codes. Not sure if I have the ability to pull them.

 

Given the mileage and you don't know the history, bet it's carbon buildup on the intake valves. Only way to know, take off the intake and take a peek..

 

Could be any number of things:
Carbon buildup
VANOS solenoid
Thermostat (I wouldn't jump to this if you don't have a CEL light)
Spark plugs
Compression issues (unlikely if the car runs happily)
HPFP starting to fail
etc
etc

 

I'd first replace your plugs if you've never had this done. This is very easy to do. Then clean up those intake valves. They get gunked up pretty quick. If it's still idling rough you'll have to work through the other items mentioned. I'm facing a problem myself right now. I've got a bad misfire problem now. Almost sounds like a bad timing issue. The problem for me happened while driving on freeway. I'm gonna try another thread because I've got a lot of questions. Good luck man.