I just returned from having my '09 R56 30K service at which time I asked the dealer to look into a problem that was becoming increasingly noticable, a light engine miss. It's most noticable when the car is cold, running at a steady 1500 - 2000 rpm in second gear, for example. It also doesn't always take a load without hiccuping as it warms up. Once hot, it's only noticable when idling, where it will misfire once or twice about every 5 - 10 seconds.

The dealer claimed that this was a somewhat common problem related to the carboning of the intake tract that has been widely discussed in this forum. He also claimed that unless it was bad enough to throw a fault code, MINI would not pay for the intake cleaning, which they were happy to do if I gave them $495. I opted not to have them do that, thinking that if it was really necessary, I would do it myself.

What I don't understand, however, is how the accumulation of carbon in the intake an on the back side of the valves is causing the miss. I was more likely to attribute it to partial fouling of the injector in the head and expected them to recommend an injector flush. Anyone have a similar experience?

 

Exact same problem my kids 07 MCS is having. Dealer wanted 100 bucks to pull the intake and clean the runners and valves. Apparently the carbon build up absorbs the air/fuel mixture and keeps it from reaching the combustion chambers resulting in a leaner mixture. On top of that they mentioned the timing has stetched, which I confirmed with my local dealer (the kid is in Florida, I'm in VA) and he sees a good amount of MINI's with timing chain issues. So after the intake is cleaned and the injectors are cleaned the miss is still there. What's next? Basically pull the head and do a valve job. $4200 bucks now and how much of a chance is it that it won't need that aforementioned timing chain? Slim I'm betting. So I decided to have them replace the motor along with the clutch and flywheel. Yea, it's 6 grand now, but all those other issues will be gone and it'll have a 2 year unlimited mileage warranty.

Face it, MINI has problems with these motors and they know it. But they refuse to do much about it. This car has been maintained well above what MINI suggests and still this problem occurred.

Don't get me wrong, I love the car and still have brand loyalty, but I thought the days of British cars being undependable were over!

 

If I were you and you are planing on keeping the car I would look into an extended warranty.I have fidelity 3 yrs 36,000 miles thats over the 50,000 that Mini has.It is bumper to bumper.From what I understand it is what most car dealers use and has a high recommendation.I have not needed to use it yet but if any major part/ component fails all I have to put out is the $100 deductable.My Mini Dealer, Mini of Annapolis, uses it and has never had an issue on claims,,,Just IMO

 

I had the same problem. Refer to the thread I just started. I dont think anything will solve the spontaneous problem. One down and rest kept floating up. I love MINI., just that it's giving too much problem.

 

Thanks for the input.

I'm still scratching my head over the carbon / miss relationship. The lean condition caused by carbon on the back side of the valves absorbing fuel doesn't sound right. Since this is a direct injection motor, the intake is dry and the fuel is injected into the cylinder directly. Any other thoughts?

 

The coked carbon buildup comes from the PCV system, not the fuel. This is an inherent problem with all direct fuel injection engines, not just the MINI. There are several huge threads on this subject here on NAM.

 

You're exactly correct on that, Dwight. It's a big problem on Porsche's DI motors as well. Apparently without the fuel spraying on the back of the intake valves as in a conventional system, the oil vapors attach to the back of the hot intake valve, eventually creating this build-up. While I can understand that it will tend to inhibit air flow, it shouldn't cause the type of lean misfire that I'm seeing - I'm still suspecting poor fuel atomization at low flow levels due to partially fouled injectors.

On a related note, I'm suprised at how poorly the R56's PCV system prevents vapors from being re-introduced into the intake. There was quite a bit of oil in the turbo inlet hose that I pulled of the other day. The reason for the revised system in 2011, I suppose.