I've been reading many threads here about extreme carbon buildup that has plagued certain Mini Cooper S engines. Which model years are most prone to this, and was the buildup due to a design issue that has since been rectified?

 

Pre 2010 (n14) engine models had the carbon issue. I believe most if not all countrymen had the n18 except for a very few early models.

 

The CM has only been available with the n16/n18.

As for the carbon issue, I don't know specifically about the n18 however I believe that all direct-injected engines are prone to carbon build-up to some degree, except for certain designs which also have an injector in the intake. Do a search for "bmw walnut shell cleaning".

 

BMW and Audi's carbon build up problem have been fixed for the most part on the newer models with the exception of a few high performance engines. Does anyone have a 2010 or newer mini that has carbon build up issues?

 

It's direct inject, it will happen eventually. Many other brands are going this route too. In a few years this will be common maintenance.

 

There are very few carbon build up issue in the 2012+ BMW and Audi DI engines. I think they have it figured out.

 

If that were true, wouldn't we be hearing about it by now? There's numerous early Countryman owners out there that are now over 75K miles, and I can't recall anyone here reporting the issue. If you look a the 2nd generation section of the website, you will see numerous owners reporting the problem at far less mileage. Or are you saying the problem is inevitable with DI engines, but with the changes it will just happen at much higher mileage?

 

Its a few years later and Im looking for this answer to after someone scared me about DI engines and this issue with the GTIs