You sure love to leave smart comments buddy. Your barking at the wrong tree...

All direct injection engines cause carbon buildup...so how are you ever going to stop it? Your going to try to eliminate it with a catch can? Nope. You can try to prevent it from building up too much but IMO, I will save that $170-230 or what ever price they are and save it for the walnut blasting! Again, I wish more people would post pictures of their valves for the N18's to prove it isn't as bad as the N14's were. It's not eliminated, but it's improved that you won't have too much carbon on the valves.

This is IMO, you don't have to agree but the point was maybe the N18 got better and did you forget that all direct injection engines cause it regardless?

 

And how is it working out? Let us know.

 

It's not catch anything. I can flip the can upside down and nothing will come out, not a drop.

The inside of the can is discolored so I know oil vapors are going through.
I even inspected the intake tube to the turbo and it's clean. I also inspected the hot side boost tube at the FMIC...that's clean as well.


Awesome that I'm not catching anything.....crappy that I paid for the catch can lol.

 

Thanks for letting us know. But remember people weather does make a difference when getting a catch can if any of you are still planning on getting it.

 

Yup, don't get one if you're in SoCal. Doesn't get cold enough

 

http://royalpurpleconsumer.com/produ...ystem-cleaner/

Would fuel system cleaner like this help with the carbon build up issue?

 

No

 

In any direct injection engine, the carbon build up problem is caused by the fuel being injected directly into the combustion chamber, not drawn in through the intake valve. As a result, whatever cleaner is in the fuel, whether put there by the refinery or as an additive used by the car owner, it never gets the chance to wash the back of the intake valve. Because the PCV system directs crankcase oil vapor into the air intake, the oil cokes on the back of the intake valve. This is a potential issue will all direct injection engines, but particularly so with the N14. The question here is whether the design of the N18 has lessened the problem.

 

Okay, since its been a while since the last post on this thread giving people with the N18 engine time to accumulate some more mileage, it might be time to resurrect the question about carbon buildup with the N18.

I now have 17,000 on my N18 and am noticing some occasional slight hesitation on acceleration from a stop. Haven't seen any codes but plan to have the dealer check it out when I get my free oil change in 2,000 miles.

Has anybody with the N18 had a confirmed carbon buildup diagnosis?

 

This thread has been a hoot to read.
My input, for what it's worth, since somehow people are trying(again) to connect a catch can to carbon build up(which it will not prevent, that's a dead horse):

The oil catch can does not fix the concern of carbon build up on your valves, HOWEVER, in my experience over the years with turbocharged cars, factory or custom aftermarket, a catch can is a goo idea.(In our N14 case, on the drivers side hose, which I believe has been said is the ONLY PCV system portion access-able).

The reason I say this, the catch can is not being installed to somehow magically prevent carbon build up on the valves, but to keep the oil from going back through the turbo. A little oil burning up in the cylinders is no biggie, hence the passenger side portion of the PCV system not really needing one. But you just don't want to be recirculating oil through the turbo and intercooler, it can gum things up and definitely hurts the turbo over time.

 

I don't disagree with what you say...this thread got highjacked by the catch can discussion which was not my original intent. Back to the original question which I don't think anybody has really addressed:

*****THIS IS FOR THE N18 ENGINE*****

Are there any of you out there with the N18 that have actually had a carbon buildup diagnosis at a MINI dealership? How many out there have had no carbon buildup problems? What is the mileage when this occurred or what is your current mileage if you've had no problems?

*****THIS IS FOR THE N18 ENGINE*****

 

For what its worth... I'm on my 3rd Mini, My first with the N18 a 2012 CM ALL4S. One of my PM's is that I drilled a 1/8" hole in the plastic intake tube from the filter to the Turbo and every 10,000 Miles ( I'm at 25k) I use 3M throttle body cleaner the type that's comes with a long small plastic tube and the can has a lockdown dispenser on it. I feed about 2 inches of the tube into the intake tube and keep the rev's at 2k . I lock the can dispenser on. It takes about 15 minutes to empty the can which I then pull the tube and put a small screw in the intake tube to seal it. I have no data to prove I'm doing any good but I get 32 MPG on the highway and have no throttle stumble. I am also old school and change my oil at every 7k so at 25k its had 1 dealer change at 14k and 3 of my own. Its due at 28k back at the dealer. I use either Mini branded 5w30 synthentic or Castrol Edge which ever I find a bit cheaper at the time.

 

Yes the N18 engine will have carbon build up problems. Had it misfire and the dealer stated this was the issue (46k miles on my 2011). I'm going to a local shop now to check on walnut blasting.

 

How does a turbo charged engine DRAW air or vacuum into the cylinder when there is positive pressure in the intake system at all times the engine is running according to my absolute pressure gauge on my 2013 JCW N-18 engine.

The big difference between the N-14 and N-18 engines is the overlap angle. On the N-18 engine the intake cam is retarded at low rpm and the exhaust cam is advanced to the point that there is actually a negative overlap angle. IE the intake opens after the exhaust closes. This prevents any combustion gases from entering the intake system past the valves. At mid rpm the intake cam advances and the exhaust cam retards creating a large overlap cycle. On a turbo engine there is a back pressure behind the turbine wheel that exceeds the air intake pressure from the turbo. At this point the combustion gases can now get past the intake valves and dilutes the incoming air. This is called internal EGR. At high RPM the N-18 cams revert back to retarded intake and advanced exhaust, with very little overlap for best power. Very little combustion contamination past the intakes. This why you won't see as much carbon on the intake valves of the N-18 vrs the N-14 which has a fixed exhaust cam setting, and full lift on the intakes throughout the entire RPM range. This allows a greater overlap degree opening throughout the entire RPM range, thus more combustion gases past the intakes, thus more carbon.

As for the OCC. It may prevent some crankcase gases from entering the intake, but the main problem is the combustion gases during the overlap cycle.

Don't ask who I am or what I do. I can't tell you!

 

Aha...an NSA operative tapping into MINI engineers' cell phone conversations.

 

Aha, I can assure you that is not the case. Who I am or what I do is just not important to the issue. Without trying to sound like a college professor giving a lecture on fluid dynamics and pressure gradients I'll just say it like this. There is always positive exhaust pressure through the exhaust port to the back of the turbine wheels of the twin scroll turbos on a MINI. This pressure on a turbo engine is always greater that the positive pressure of the intake air coming from the turbo to the engine. In the short period the exhaust valve is open when the intake valve starts to open there will be a brief moment of back flow into the intake port past the valves until the exhaust valve closes. Dual Vanos minimizes this flow by closing the exhaust valve sooner and opening the intake valve later at low and high speeds. At middle RPM and load is some variation of this allowing combustion gases into the cylinder for EGR purposes. So, the N-18 engine will have some carbon on the intake valves, but not as bad as the N-14 which has only single Vanos on the intake side.

As for oil from the PCV system. This can be caused by blow-by past the rings. If you see a lot of oil in your catch can it's time to do a cylinder leak down test . If you have more than a 10% leak down past the rings into the crankcase it's time to rebuild the engine. Blaming the PCV is like killing the messenger. Maybe with the MCS,and JCW engines, both N-18 and N-14 running at 225F doesn't help the blow-by situation. Only the 2013 N-18 JCW and GP2 engines run at 195F.

In summation. We're all going to have some carbon on the intake valves, so save your money for the walnut shell blasting and consider it normal maintenance.

 

I was only joking with the NSA comment as you can see from the smiley. Actually I have enjoyed reading your informed comments. Its pretty obvious you know what you are talking about.

 

With absolutely no one provoking you or asking, saying "Don't ask what I do, I can't tell you" means "I have some menial non-classified or private job that has no reason to be masked, but I want to feel special". LMAO....

 

Would this water vapor from the PCV be helping to clean the valves a tiny bit. Kind of like water/meth injection might do?

 

The only way to fix carbon buildup is to use a DI+ port injection setup like Toyota/Lexus uses. It's more complicated, but if a $25k Scion can get it, I don't see why a $35k mini couldn't.

 

Furthering your point about price/features, there's no explicable reason a car of such low build quality and cheap feel inside should cost $35K in the first place.

 

Too bad there is no way to like or upvote a post on this board. Thanks for the details.

 

No offense taken. It was all in good humor. Hope my critique of the problem was helpful!

 

Sorry I had projected the wrong image with my comment. I retired 10 years ago from a highly technical aerospace job, gained through education and experience. I'm just a very private person, but wanted to share what my research had led me to, hoping to shed some light on the carbon problem. It was meant to generate discussion, not short sighted comment!

 

Your avoidance of ethanol is pointless. It had absolutely no negative effect on your performance. From station to station, you will get different quality gas which will effect your milage, but ethanol is not hurting your car at all. I'm well versed in ethanol, and how it interacts with cars. Any newer car has a fuel system that is fully safe to run any percentage of ethanol. You may experience a small decrease in milage, but many cars with turbochargers and especially if you have a tune, can make better milage due to higher octane when mixed at a 30/70 ethanol-gas mixture. The hype of ethanol messing up cars are just lies put out by the large oil companies. If it was true, Brazil wouldn't have almost all of their cars running E-85 to E-100 with absolutely no problems.

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