Direct Injection carbon buildup
 

My DD is a 2011 Audi S5, lovely car and sounds fabulous with its Stasis exhaust. I have it in at the dealer right now for an oil change with 21,000 kilometers on it (13k miles). I had been noticing lately that it was not starting well when the engine was hot and felt down on power. They now have the intake manifold off and are de-carbonizing the valves and intake manifold.

I found this article on the problem:

http://www.autoobserver.com/2011/06/...-adopters.html

Interesting it says that Porsche doesn't seem to be having a problem...

Common s5 v8 problem. And rs4

There is an aftermarket oil catch can you can install to fix it

Audi is not the only one that suffers from this.

It becomes a maintenance item. Here's how you actually fix it:

http://www.motorvac.com/index.cfm?PAGEPATH=&ID=38819

I've been using my credit card, I should try this :)

Drive the Audi harder... :evilgrin: Not too many problems like this that a good old Italian Tune Up can't fix :D

The best solution to this issue is the design in the Flat-4 motor used in the budget sports cars, Subaru BRZ, Scion FR-S, and Toyota GT86.

There they use 2 fuel injectors per cylinder. One is inside the combustion chamber (DFI) and one is farther up the intake air tract. The second one acts to wash the intake and valves (like a traditional non-DFI motor).

This allows all the benefits of both DFI (fuel economuy, high compression and specific output, HP/Liter) and non-DFI (no carbon build-up).

I wish Porsche and others would adopt this technology...

Common problem w/ the DI Audi motors.

There was a dyno chart around where a guy lost like 35 rwhp over 20K miles due to the carbon build up in his Audi.

Other engines don't have the problem and it has to do w/ vapor routing and some other fine details.

It can get pretty bad...

Yikes -- I'll say.

that's why my RS4 dint stay long.
BMW also got this issue in addition to other stuff

doesn't look good at all.
explains why 2 year old ttrs are cheap here...

BMW 335 are like this to. Walnut blasting usually is the best option.

Bought my RS4 with 23k miles, dealer took of manifold and manually cleaned valves 3k miles later under warranty due to power loss.

I run Shell fuel and hammer the car hard after it reaches normal operating temps and haven't had another problem in two years.

My RS4 has a nice power surge at around 4500 RPM all the way till it shuts off at 8200 RPM like the 4.2 liter DFI V8 motor should.

I hear you BUT...that doesn't work in this case as the oil is coming from the PCV system. It doesn't get washed off the valve by the injector....looking around the internet the oil catch can seems to be the solution to keep the oil out of the intake manifold. Even then I suspect it will just slow down the problem not eliminate it.

Interesting solution to go to 2 injectors...

I really enjoyed my RS4 but my diesel F250 ended up being a better bet as a daily driver, I was really worried about the carbon issues and that I would get arrested for how the RS4 required me to drive it!!