[PackPride85]

Most people probably aren't to this point yet mileage wise, but at some point because its a DI motor, the valves are going to require cleaning from carbon buildup. I'm not too familiar with how BMWs handle this, but with my mazda it was generally recommended at 50-60k miles.

I've heard that BMW dealers (in the US) actually offer a blasting service that uses crushed walnut shells. Just curious if others on here have previously used this service and how much they typically charge.

This thread seems to be a pretty good indication that the problem does exist and the method actually works:

http://www.e90post.com/forums/showthread.php?t=682116

[chmura]

I think this was fixed with the N55 motor?

I know Toyota 4DS motors they do not have carbon build up issues at all. Each cylinder has 2 injectors both port and direct injection. The combination of using these injectors you do not have any carbon build up from the valves.

[PackPride85]

Originally Posted by chmura

I think this was fixed with the N55 motor?

I know Toyota 4DS motors they do not have carbon build up issues at all. Each cylinder has 2 injectors both port and direct injection. The combination of using these injectors you do not have any carbon build up from the valves.

None of the bmw motors use the port/di combo like the 4ds that I know of. That's the only real "fix".

[SeanWRT]

Use Ethanol once in a couple month should do.

[flyboy385]

I recently brought in my 2011 N55 135i with around 75,000 miles on it to have the intake valves looked at.
After more than 50,000 miles with JB4, DP and exhaust, my mechanic said it was amazingly clean and I could go another 75,000 miles before valve cleaning was needed.
I imagine the N55 in the M2 should be similar, so probably not something to worry about yet.

[J3STER]

Originally Posted by SeanWRT

Use Ethanol once in a couple month should do.

How will this help? The cars runs DI, the fuel does not touch the valves.