Carbon build up and sticks...

[shah269]

I have a good friend who works for Volvo USA and is a total car guy.
We were having drinks this past Sunday and he was asking how i liked my little 135i and how he misses his late 80's 911.
I told him about the carbon build up.
Then he asked me an odd thing....
J "Your car is a stick right?"
Me "Yes, but that carbon build up...."
J "Don't worry you drive a stick it's not as bad on sticks."
Me "WHAT are you talking about...."
he wouldn't say much......freaking contract and bla bla bla....but said something that when they were doing their testing...sticks had a greater propensity to "shake off" the carbon build up better than automatics due to engine braking while down shifting off of high ways....

I was like....WHAT!
I'm a mechanical engineer...and this freaking hurt my head....
thoughts?

[Sixle]

My buddy had a 6mt 2008 135i and had the walnut blast done at 40k, not sure how bad it was but from everything I've read the guys with 6mt's like myself are seeing the build up regardless of the trans. The 6mt might be more resilient by 10-15k miles but I'm not exactly sure downshifting forces are high enough to "shake" the carbon off.

I'm only at 21k miles on mine but I suppose ill check them out around 30-35k.

[BrokenVert]

As a fellow engineer I join you in your WAAAT.

Also id like to know how the testing was done. Was this two engines on dynos running identical programs, was it a study of service records? If its the latter than it opens everything up to a lot of scrutiny.


The most obvious thought being that manual drivers tend to get more into the act of driving. We tend to care for our cars more and as such dont treat them in a way that would accelerate the buildup of carbon. ie - being hard on a car immediately after startup. We also tend to rev the engine a bit more often - revving under load (hard accelerations) will blast out soot before it has a chance to fully bake in.

So in other words id take it with a grain of salt, Carbon buildup is going to happen in the intake manifold, its just in the nature of DI cars - they all do it at an accelerated rate when compared to normal port injection.

[SGJB135i]

I had mine done, I drive a stick, it was crazy dirty, hasn't been cleaned for 80k miles haha car feels so much better

[RimasRS]

I saw somewhere suggestions how to clean carbon buildup on VAG cars something like hold up on 3rd gear 4-5 thousand rpm for 45 seconds then punch on gas the other time let go the gas but for me it sounds mystical. I dont remember source but it was mentioned even on this forum.

[n54door]

ditto - i have a 6mt, and it was all gummed up on the valves. Pretty bad actually.

[Acheron83]

Likewise.

Mine at 60 000km: