I am guessing the reason that the V6's and V8's have more problems with carbon buildup, is that with more cylinders firing you are pushing that much more gasses past the rings into the crankcase and out the PCV valve. Because of the extra cylinders the V6 theoretically pushes 50% more gases through the PCV valve than the 4 cylinder, and the V8 pushes 100% more gases through than the 4 cylinder. That would cause buildup to happen quicker than you would find it happening in the 4 cylinder.

 

I saw reference to the patent in earlier threads... does anyone have access to this patent paper or know where it can be found and downloaded? This could be very helpful for those of us pursuing a settlement with Audi.

Also if anyone has had any experience in settlement through BBB or other venues, it would be helpful to learn what information was presented to the car maker.

 

I haven't had a chance to look for the patent, but if I remember the patent also states that due to the nature of the design, there is not much that can be done and carbon buildup will occure. The over 3000 rpm thing was one item mentioned that would help but not cure the problem. Audi/VW having this design out the longest, is experiencing the carbon problems that other companies, such as GM, who just released DI engines more recently, will soon have to deal with.

 

I think I found the patent that has been mentioned. It does not look exactly like the one I saw, but does mention somewhere between half and two thirds the way through, the over 3000 rpm thing for 20 minutes. Here is the link.

http://www.mycar.net/volkswagen/6866031.html

 

I have a RS4 that just required the intake manifold to be removed and the cleaning of what looked like a massive amount of black burnt oil build up in the upper cylinder head area. I have attached the photos that my dealer provided. The work was completed under warranty but no one can tell me exactly what this build up is from and the dealer said they can’t tell me its not going to happen again. I trust my dealer as I have been buying and servicing Audi's and Porsche's with them for years. I hear that Porsche's are not having the same problems, however, with their direct fuel injection engines. The repair was just cleaning and not repairing or replacing something that could have caused this massive build up. The symptom I had and have had multiple occurrences is an engine check light and a rough run condition when I start the car in the morning and after sitting through out the day. I understand that Audi says it is a fuel issue and I assure everyone I use 91 octane fuel-this is an RS4!!!! When you look at these photos it reminds me of my fireplace chimney that was so full of residual burnt residue that it caused a FIRE….. Audi needs to address this issue as I plan to keep my 2 Audi's (RS4 and R8) for years. The next time I need this clean out they say it will be on me as I am nearing 50K. Who should I pass this onto? The State CARB or what? I've done some looking around online and I'm clearly not the only one with this problem as owners of the 3.2L in the A6 seem especially prone. I've even seen some postings by independent shops of these kind of pictures on AudiWorld's forums. I'm surprised there hasn't been a class action lawsuit and disappointed Audi hasn't addressed this with more resources in the interest of the customer.

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Will post more soon.

 

From this point on use the top tier gas. It really shouldn't make a difference in the intake manifold, but if it happens again, at least you can say you did. Because of DI, there is no way that was caused by fuel. The fuel is injected into the cylinder and never comes in contact with the intake manifold. Your PCV valve is letting oily crankcase gases go back through the intake to get burned off, which is exactly how it was designed to work. Those oily gasses then get burned up in the cylinder and don't cause emmissions problems. With traditional fuel injected systems there is a spray of detergent ladden gas that sprays though the intakes and valves that helps clean them. Remember the 8 cylinder is pushing more crankcase gases though the system than the smaller A4 engines, so there are more vapors to coat the intakes. The 4cylinder has the advantage of the turbo, which compresses the air in the intake heating it, helping with burnoff. If you go to Audiworld, you will find someone elses pictures of their RS4 8cylinder and how carboned up it got.

 

I just took my 2008 Audi A6 3.2 in with 17k miles on it for the 3rd time with the engine light illuminated.They also told me to ensure that I only use the prescribed brands of gasoline. I use Shell V-Power. Now, 1 month later, the same thing. The check engine light is on and the dealer finally admits that this is a nationwide problem without a root cause or solution.

 

Mine went in the shop for misfire codes on Friday and waiting for Audi to respond. It's a 3.2 with 13K miles.