For those really interested in gasoline . . .

http://www.eoearth.org/article/Gasoline?topic=50361

Perhaps the fuel additive did not help you since you already had excessive build up.

Typically an engine will not accumulate enough carbon build up during 3,000 miles to start causing problems, even with the use of low grade / low octaine fuel. Adding this stuf every 3K makes sence.

I will be using Shell's or Exxon's 93 octaine and will also be using Audi fuel additive every 3K miles. Hopefully this will alleviate any issues with carbon build up.

Is anyone doing the BG induction service as a preventative measure?

Costs like $180 buck to do at an Audi shop nearby. Whether it works or not is a debate in and to itself.

And from what I have read, it doesn't matter what fuel you use. The problem is, as mentioned above, there is no fuel reaching the top of the valve to clean it and stop the carbon from caking on top of each other. I remember reading that no type of top tier gas or additives work. I even remember reading an owner doing a meth injection on top and that didn't stop it (of course that was with an S4 and I think they had the worst problem of anyone.

Design flaw of FSI

If those channels are part of the EGR system, should they be covered under an emissions warranty?

I bet they are not. They are merely what's affected by a flawed vent system inherent with DI engines

Octane ratings (numeric) are NOT an indicator of fuel quality. 95 RON (the Euro number) is roughly equivalent to fuel with an AKI of 87 in the U.S.

It is true that European gasoline is different, but the numbers you're quoting (the RON or Research Octane Number ratings) have nothing at all to do with that, as cebo said.

European fuel has a much lower sulfur content than NA fuel.

The best way to avoid having these problems in your engine is to stick to top tier fuels. www.toptiergas.com

In Short: If you're driving an Audi, you shouldn't be buying gas at costco or walmart or whatever.

Didn't someone post that the carbon buildup is from the fuel not washing down the intake tract ?

If that's the case,
then how does the the quality of fuel have anything to do with the intake tract if no fuel is directed there ?

just curious :)

So, new to this thread, but I was wondering, and this may be my lack of knowledge of the technology, but if the case really was that direct injection prevent fuel from washing the valves, wouldn't most modern diesels have a huge problem? I thought that most of the new diesels have gone to direct injection as well. That creates a pretty large field, I really haven't heard of anything like this before.

The carbon deposits in this case was found in the EXHAUST ports. The intake ports were remarkably clean and the technician was actually surprised by that. Definitely impurities burning and caking in the smaller channels as seen in the pics.
I have to admit, I was not diligent enough about where I was refueling, mainly because of convenience on my longer trips, but now I have vowed to stick to Shell Ultra and nothing else!