Mini Carbon Build up - Is it a dealer money maker

I would like to find out how many of you have been told by your dealer that your new mini needed preventative maintenance to clear the fuel injectors and inlet valves to prevent future carbon build up at the cost of the owner.($390)

I have to say I have had numerous new cars and this is my wifes 3rd Mini and this has never been the case.

To the best of my knowledge, that 'preventative maintenance' recommendation appears nowhere in the vehicle documentation: Owner's Manual, vehicle maintenance schedules (i.e., the OBC), etc.

Because of the well-documented issue of carbon build-up in these engines, they clearly need to be periodically cleaned -- if a solution to avoid the build-up can't be found. But the claim occasionally made by MINI service centers that this has long been is a 'recommended' maintenance action is, in my estimation, spurious.

Sure, I would recommend it too... But what's at issue now is who should be paying for it: the owner (as MINI contends with their 'preventative maintenance' posturing), or MINI (because it's a design shortcoming that should be either covered or remedied)...? Unfortunately, the latter is not likely to happen without involving lawyers...

Never had the problem - even in my older MINI. Sounds like a stealer 'special' to me.

Originally Posted by BMWFatherFigure

Never had the problem - even in my older MINI...

The older (first-generation) MINI's did not utilize direct injection, which is the primary cause of this problem.

It's a real problem; but thus far, MINI/BMW has not owned up to their role in contributing to it...

is there any kind of additive that can be used aside from going to the dealership?

Originally Posted by Madwick

is there any kind of additive that can be used aside from going to the dealership?

Not really. Some recommend using Seafoam, but I'm personally not convinced that will really help. The fundamental issue is that, unless the cleaning agent can be directly applied to the intake valves, it's not going to be effective. Ordinarily, the fuel itself would clean the intake valves; but since the fuel is injected directly into the cylinders on this engine, it never touches the intake valves, and they apparently cake up with re-circulated crankcase vapors. So any additive put into the fuel will also bypass the intake valves.

The best method of cleaning these intake valves appears to be through the use of some kind of abrasive: wire brush (with or without a cleaning agent) or the walnut-shell blasting employed by MINI dealers.

Had the carbon build up issue about a year ago. SA questioned our gas use first and then after some education from me, he decided to clean the injectors and admit it was a common problem with these injectors. It's my hope that something has changed for MY13. I recently took delivery of my 3rd Mini. I know the engine of the Countryman S is made across the pond so hopefully they changed the injectors.........Phil

Interesting, I just brought my wife's 2010 Mini Cooper S with only 26,000 kms to the dealer last week as it was almost stalling when it was cold and put in reverse. The cause, carbon build up! The scan fault memory was - codes set for several cylinder misfire, they suspected carbon buildup on back of valves. They removed intake manifold and found heavy soot, performed cleaning procedure with walnut blaster (whatever that is) which solved the problem ran the test again reprogrammed vehicle and clear fault memory and the road test was ok, problem solved. Luckily this was covered under the warranty but it is a concern if this seems to happen to many owners. The solution I was told was to use better quality gas and of course minimum 91 octane.

Originally Posted by Zuger

... The solution I was told was to use better quality gas and of course minimum 91 octane.

That's MINI's pat answer to this; the reality is the use of direct injection coupled with the early routing of crankcase vapors is the fundamental reason for carbon build-up in these engines. There was a slight re-design of the crankcase vapor routing on the 2011+ models that was intended to address this very issue. But it's easier for MINI to blame it on the owners for using 'poor quality' and/or lower-octane fuel... The sad fact is, on 2010 and earlier models, use of 91+ octane top tier gasoline won't guarantee that one won't see this problem.

The reprogram is supposed to be a solution to the intake valves being carbonised. We haven't seen an N18 need a carbon clean yet.

Originally Posted by BK544E34

The reprogram is supposed to be a solution to the intake valves being carbonised. We haven't seen an N18 need a carbon clean yet.

Not sure what the programming can do to mitigate carbon buildup in a direct-injection engine...? My understanding is that the N18 engine (used in the 2011 and later model year MINI's) has a revised valve cover that incorporates new PCV plumbing designed to reduce the amount of offending crankcase vapors at the intake valves. So if you aren't seeing any carbon build-up in the N18 engines, those hardware changes may be the real reason...

If so, the question now becomes: can these revised N18 valve covers and PCV plumbing be retrofitted to the N14 engine (2007-2010 MINI's), which suffers with carbon build-up issues...?

We see a lot of inline fuel injector cleans in association with doing the intake valve cleans.

"After completion of the repairs, reprogram the complete vehicle using the current ISTA/P version (ISTA/P 2.47.1 or higher; target integration level R056-12-07-503 or higher). The new DME calibration software includes an optimized injection timing strategy, as well as an increased operating pressure, improving the injector’s operation."

Not sure about the retrofit. I imagine there could be a plausibility. I have heard that methanol injection prevents the build up as well. Lots of paths to explore!

Originally Posted by BK544E34

We see a lot of inline fuel injector cleans in association with doing the intake valve cleans.

"After completion of the repairs, reprogram the complete vehicle using the current ISTA/P version (ISTA/P 2.47.1 or higher; target integration level R056-12-07-503 or higher). The new DME calibration software includes an optimized injection timing strategy, as well as an increased operating pressure, improving the injector’s operation..."

Hmm. That sounds more like a strategy for keeping the injectors themselves clean; or possibly a fuel economy or emissions change. I'm skeptical that increasing fuel pressure at the injector can do anything to prevent carbon deposits on on the intake valves, since the fuel never actually touches those valves. But I'm just speculating...

Originally Posted by BK544E34

... Not sure about the retrofit. I imagine there could be a plausibility. I have heard that methanol injection prevents the build up as well. Lots of paths to explore!

Yeah, folks have tried a number of aftermarket solutions, including methanol and oil catch cans. The jury still seems to be out on their relative effectiveness, though.

Originally Posted by timfitz63

Hmm. That sounds more like a strategy for keeping the injectors themselves clean; or possibly a fuel economy or emissions change. I'm skeptical that increasing fuel pressure at the injector can do anything to prevent carbon deposits on on the intake valves, since the fuel never actually touches those valves. But I'm just speculating....

I just fix things according to bulletins! Apparently the two are related for the misfire faults. The repair instructions fix that cars, so I guess it works. Had a JCW in with a catch can and the valves were fairly clean. Maybe it does work?