iconoclast

I cannot find any straight-forward answers or information on the matter of carbon build-up. I have owned several FSI/GDI/DI engines and ALL needed carbon cleaning at one point or another despite Dealers claiming the issue does not exist and if it does show up it's from "poor US fuel & oil quality". This is my first MB w/ Direct Injection and I am curious to know if anyone on here has had any issues with carbon build-up or has completed cleanings on the M157.

At 29k Miles on a large engine like this I have to assume there is some sort of build-up just not sure if it is enough that warrants a cleaning or if it is completely choked like other engines in vehicles I own(ed).

Thanks.

EVOII_Racer

I have no idea but I am very curious on reading answers to your post

Very good question!

Staff@WORLD

The build up on these new engines is pretty disgusting. I have not had our ML63 apart but I have had our E63 apart and it is the same engine. When you take the intake manifold off and peak at the intake valve with a flashlight it is full of sludge.

This is a direct effect of the direct injection engine.

Obviously their are a lot of performance advantages of the direct injected engine which are a direct result of injecting the fuel directly into the cylinder head, more important to the car manufacturers is the fact that it is cleaner and more fuel efficient as well. Now the problem with the direct injected engine is that the intake valve does not get cleaned anymore. In an old fuel injected engine the back of the intake valve would get sprayed with fuel and this fuel has detergent which keeps things clean. This kept the back of the valve clean and healthy but that option does not exist anymore on a true direct injected engine. Some companies have added regular style injectors on top of the direct injectors to solve this issue but that adds cost and makes the motor less efficient and decreases performance.

Who knows what the solution is but I am sure that some very smart people are working on it right now.

iconoclast

i am familiar with the root cause and this being a side-effect of DI... the only solution is supplemental injector which washes over the valves or variable spray from injector that is positioned at a different angle which then washes over to reduce build-up. MB has changed the design on two engines going forward to mitigate build-up (as has audi, bmw, lexus). my concern isn't so much with the build-up but more so about how often a cleaning would be necessary.

as stated in my original post, i have owned several vehicles and have completed cleanings on all of the DI engine equipped vehicles. it is disgusting but the restored power and breath ability is worth the effort and money. the trend seems the larger the displacement the more build-up and sludge is found. smaller engines barely had any build up at 20k miles on the flip side the RS4 was sludged and choked by 10k miles.

iconoclast

any other updates or input?

newguy2008

I would like to know this as well. Thanks.