# Mini Carbon Build up - Is it a dealer money maker



## BigglesTAP (Feb 22, 2009)

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.


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## timfitz63 (Aug 10, 2010)

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...


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## BMWFatherFigure (Aug 5, 2012)

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


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## timfitz63 (Aug 10, 2010)

BMWFatherFigure said:


> 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...


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## Madwick (Dec 27, 2012)

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


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## 650 Ryder (Mar 31, 2008)

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


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## timfitz63 (Aug 10, 2010)

Madwick said:


> 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.


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## Zuger (Feb 23, 2013)

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.


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## timfitz63 (Aug 10, 2010)

Zuger said:


> ... 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.


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## BK544E34 (Apr 12, 2013)

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.


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## timfitz63 (Aug 10, 2010)

BK544E34 said:


> 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...? :dunno:


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## BK544E34 (Apr 12, 2013)

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!


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## timfitz63 (Aug 10, 2010)

BK544E34 said:


> 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...



BK544E34 said:


> ... 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.


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## BK544E34 (Apr 12, 2013)

timfitz63 said:


> 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?


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## timfitz63 (Aug 10, 2010)

BK544E34 said:


> 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..


OK. Well, it sounds like you're closer to the problems than I am. I'll take your posts under advisement!



BK544E34 said:


> ... Had a JCW in with a catch can and the valves were fairly clean. Maybe it does work?


I know some who swear by them, particularly on an early ('07-'10) turbocharged MINI...


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## mc85 (Jan 31, 2009)

hey guys I know there hasn't been much on this thread. But after reading im curious if my 03 mcs is experiencing this problem sense ive noticed it will have a sluggish start sometimes and also seems a lil boggy on take off. the car does have 90k a upgraded air intake and Jackson racing ignition wires. everything else engine wise is stock.


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## timfitz63 (Aug 10, 2010)

mc85 said:


> hey guys I know there hasn't been much on this thread. But after reading im curious if my 03 mcs is experiencing this problem sense ive noticed it will have a sluggish start sometimes and also seems a lil boggy on take off. the car does have 90k a upgraded air intake and Jackson racing ignition wires. everything else engine wise is stock.


I doubt this (carbon build-up) is the problem with your model year MINI; the carbon build-up is related to the use of direct injection in the engine, and I don't believe the pre-2007 models employed that type of fuel delivery system.


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## ayycloud (Jun 25, 2013)

timfitz63 said:


> I doubt this (carbon build-up) is the problem with your model year MINI; the carbon build-up is related to the use of direct injection in the engine, and I don't believe the pre-2007 models employed that type of fuel delivery system.


We just bought a new hardtop my13 and I noticed on take off that it takes a split second after stepping on the accelerator before the car moves. Is this normal or is there something wrong with the car? 
Thanks


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## timfitz63 (Aug 10, 2010)

ayycloud said:


> We just bought a new hardtop my13 and I noticed on take off that it takes a split second after stepping on the accelerator before the car moves. Is this normal or is there something wrong with the car?
> Thanks


Speculating a bit here. With the relative 'newness' of you car, I doubt it's carbon build-up. I kind-of noticed the same thing when I started driving my '09 -- and noticed the same behavior in Clubman S models that I'd test-drove at the MINI dealer -- and came to attribute it to turbo lag. And the effect seemed to be more pronounced in the automatic transmission vehicle I test-drove. The car doesn't have a lot of turbo lag, but it does seem to possess some if one doesn't keep the RPM's up some. After a while, I became conditioned about what to do with the accelerator pedal during routine driving situations, and I really don't even notice the effect any more...


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## ayycloud (Jun 25, 2013)

timfitz63 said:


> Speculating a bit here. With the relative 'newness' of you car, I doubt it's carbon build-up. I kind-of noticed the same thing when I started driving my '09 -- and noticed the same behavior in Clubman S models that I'd test-drove at the MINI dealer -- and came to attribute it to turbo lag. And the effect seemed to be more pronounced in the automatic transmission vehicle I test-drove. The car doesn't have a lot of turbo lag, but it does seem to possess some if one doesn't keep the RPM's up some. After a while, I became conditioned about what to do with the accelerator pedal during routine driving situations, and I really don't even notice the effect any more...


Our is just the base cooper a/t. I noticed the lag when rpm drops below 2k. In situations like coming in to a Main Street from a complete stop, that's where u would notice the late response of the car a second or two after stepping on the gas. Another is when u yield making a left turn, it gets scary coz u don't have that power to quickly cross the street and there are oncoming cars coming from the opposite lane. Do u think this will go away after break in period? Thanks


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## timfitz63 (Aug 10, 2010)

ayycloud said:


> Our is just the base cooper a/t. I noticed the lag when rpm drops below 2k. In situations like coming in to a Main Street from a complete stop, that's where u would notice the late response of the car a second or two after stepping on the gas. Another is when u yield making a left turn, it gets scary coz u don't have that power to quickly cross the street and there are oncoming cars coming from the opposite lane. Do u think this will go away after break in period? Thanks


OK, well that's an important distinction; obviously turbo lag isn't the culprit. Since you've got an automatic transmission, I'm going to say that's the 'problem,' although I don't think anything is wrong, per se, with your transmission. It seemed to me, in the few cases where I drove a MINI -- or BMW -- equipped with an automatic, that they're a bit sluggish in responding to a command to accelerate from a stop. I personally don't care for the way MINI/BMW has programmed or scheduled (however you'd like to term it) their automatic transmissions. It seems like they've over-compensated in order to get a smooth transition from a stop to forward motion, and there's a lot of lag in the response. So that could be what you're perceiving...? And it probably won't 'improve' over time; I'm sorry to say that it's just the way they are...


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## ayycloud (Jun 25, 2013)

Thanks


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## Mishie (May 26, 2017)

*SF Mini is a joke*

I was just told I needed carbon build up removed from my 2010 Mini Cooper S. My car has 43k miles and has a manual transmission. Mini SF told me this procedure will cost $2100 plus tax. I was also told that it was not covered under my $4k extended warranty I purchased. One month ago the High Pressure Pump went out on me while on the feeeway. After the repair they were unable to diagnose the carbon problem. However still having the gas not properly working "choking" I took it back and insisted they look again. This time they charged me $170 to just look at the car. My issue is why was this not noticed the first time I took the car in? Also if the carbon build up is a known issue for the 2010 model how come mini doesn't let you know preventative measures and why hassent there been a recall?


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## Autoputzer (Mar 16, 2014)

Here are diagrams of port fuel injection and direct injection. Note that with port injection, the intake ports and intake valves are bathed in gasoline, and carbon is steadily cleaned by the gasoline (and the additives). In direct injection no fuel is introduced outside the combustion chamber.

Direct injection bumps up our fuel economy by about 5%. But, you eventually pay for it with carbon build-up. The good news is that the new BMW LL-01/01FE/04/14FE made by Shell seem to evaporate less than the old stuff. Almost all that carbon is burnt oil vapor sucked out of the engine by the crankcase ventilation system.

Direct injection burns so efficiently that it creates soot in the exhaust. The EU is going after these emissions. The U.S. will not be far behind. One solution seems to be having both port and direct injection systems. This could also solve the carbon build up. The water injection system on the M4 GTS might also be a future solution.

Finally, here's a DIY video of how to do it yourself. The critical step is to make damn sure the intake valves are completely closed before blowing the walnut shells in there.

https://www.youtube.com/watch?v=NnMhNXXawjk

I'm planning to keep my 535i about 100k miles. So, I'm thinking about doing a walnut blast just past 50k miles. The second blast will the next owner's problem.


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