It seems as though more and more cases are popping up where direct injected engines are experiencing miss-fires, rough running, and reduced power output due to extreme levels of carbon buildup on the intake valves. Audi's 4.2 FSI V8 and 5.2 FSI V10, VW's 2.0T, and Porsche's 4.8 DFI V8 are known victims so far...
Presumably, this is because normal port-injected engines have the added benefit of washing away any deposits that may form with the fuel spray. Unfortunately direct injected engines have no way of clearing off deposits and thus need to go in periodically to have the valves cleaned.
Is this a design flaw with direct injection or is there a solution on the horizon? Has anyone had first-hand experience with this phenomenon?
Links for reference:
Porsche Cayenne Turbo:
Modified by greatfox at 12:26 PM 5-19-2009