mhblaw

FWIW, and knock on wood, my '13 RS5 runs like a champ at 61k...

SloopJohnB@mac.com

backyard tuneup; i.e., introduce about a quart of water into the engine while it was hot and running at about 2K rpm. You DON'T POUR it in, just aspirate it slowly into a vacuum port on the manifold. The spray of liquid blasting into steam on the intake valves blows off the carbon on the valves as well as the carbon buildup, if any, in the combustion chamber.

As to how it works, I had firsthand experience on a Mercruiser 6 cylinder engine that a next door neighbor had allowed to freeze up the manifold one winter because he didn't use ears on the lower drive to inject antifreeze into the engine cooling system. Normally just draining the engine on a trailer or running the engine out of the water for 10–20 seconds is enough, but not that year! Anyway, the #6 cylinder and head/valves were clean as new after we ran the engine in the spring and discovered it was only running on five cylinders!!!

I would guess that methanol/water injection would work as well too..BMW for example has it on some of their new M engines.

jemanner

What bothers me is the slow response from the vehicle manufacturers. This has become a very well known issue across the industry. One solution is dual injection, i.e. a combination of port and direct injection. It appears that on the 2.0 TFSI Audi is indeed introducing dual injection in the European market, but not yet in the U.S. Why? Other manufacturers, such as Toyota, are implementing dual injection on some engines. Sure it's an additional expense, but this is passed on to the consumer in any case. I would much rather pay a bit more for the vehicle now, than deal with periodic intake valve cleanings down the road.