Have been very interested in doing a search on here re. carbon build up.

My JCW 2011 (n14 engine) has had a top end decoke @ 13000 miles ( I had the car @ 10000 miles) and found a occasional stutter on acceleration, and very intermittent puffs of greyish smoke when in traffic.

It took many discussions/visits to the dealer, who after carrying out many tests etc. agreed via BMW to have the decoke.

Since having this done you can feel the difference both in acceleration and tick over.

I should add the car, when I originally had it went very well, in fact the dealer said, many times there was nothing wrong with it !!

The car is a ex demo.

The car has and is not using oil.

My question is why a decoke @ 13000 miles ??

I still waiting for an answer from the dealer/bmw.

 

Based on what I've seen with the N14, it's really not uncommon to perform a decarb. of the intake valves at that mileage. I've seen some pretty nasty carbon buildup on N14's with less than 10k. If I'm not mistaken, the N14 is a direct-injected engine. Fuel is directly injected into the combustion chamber, and never actually makes contact with the intake valves.

 

Yes you are correct re.direct-injection.
According to the mini dealer, this is the first one they have had with such a low mileage !
Are you in the motor trade ?
This doesn't seem to be a common fault, other than at higher mileage.
I appreciate your reply, you are the only one on this forum. Ive had nothing on uk forums !!
ANY idea why, other than dirct injection ??

Thanks again.

 

I thought that from 2011-on the "S" models used the new n18 engines and while still direct injected were suposed to be less prone to carbon build up due to vave overlap configuration?

 

[QUOTE=TREX;3857121]I thought that from 2011-on the "S" models used the new n18 engines and while still direct injected were suposed to be less prone to carbon build up due to vave overlap configuration?[/QUOTte}

The 2011 JCW is a N-14. The JCW didn't come with the N-18 until 2013! The 2011 MCS to 2013 MCS are N-18's.

 

[QUOTE=1guru2;3857147]In addition, the OP is in the UK and I believe their model years are ahead of US for some of the refreshes.

 

I don't know that we can draw that type of conclusion. I think it is the type of miles more than the number of miles that leads to the buildup. By that I mean that my 09 JCW didn't have its first walnut blasting until 100,000 miles and the build up was there but the shop said that they have had much worse buildup on much lower mile cars.

For my car it was a road warrior for its first 3 years racking up almost 80,000 miles. All of those were long haul interstate runs.

It may be that the engine suffers more from the urban market where it only runs for a few minutes and is slow city traffic from traffic light to traffic light. Which if true, really sucks since that is the market that MINI caters to.

Maybe that is why people are always saying "Drive it like you stole it!!"

 

[QUOTE=05r50;3857151]Disregard my prior remarks about the Justa's having N-18's, they have N-12's. My error.

 

Yes, that is true the 2011 and on MCS's do have the N-18. However the fJCW's were N-14's until 2013 when they were upgraded to the N-18.

Yes, also true due to the N-18's having Valvetronic and Dual Vanos, there are times at low RPM that the exhaust valve closes before the intake valve opens, thus no carbon to the intake valves.

 

Thanks guys for your replies, so are we saying that you are likely to get early carbon build up if you don't Drive it like you stole it