Hello !
that carbon suit is NOT coming completely from the burned OIL ... ALL DFI engines have that Problem !
1) from the EVAP System there is always a Little bit of oil and condensate transfered into the engines combustion area .... BUT the intake valves were the cold parts of the engines valvetrain so the oil and condensate CAN PHYSICLY NEVER burn to ashes at the cold intake valves ! !
2) the DFI process is creating lots of carbon suit during the combustion and during the nessesary valve overlap .. were INTAKE and EXHAUST valves BOTH open and covered with the carbon suit ... BUT the exhaust valves get HOT enough to burn the carbon suit ... so at all DFI engines you see dirty intake valves and not so dirty exhaust valves !
3) all old style intake manifold injection engines clean the INTAKE valves automaticly by the fuel spray into the cylinder ... old Technology .. but cleaner Intake valves !
Good examples you find around the world in all Forums about DFI engines ... here a 98kmiles driven Golf TFSI :
http://i483.photobucket.com/albums/r...valvedirt3.jpg
and Porsche Cayenne DFI V8
http://i46.photobucket.com/albums/f1...offman_001.jpg
http://i46.photobucket.com/albums/f1...offman_003.jpg
So Google yourself and you will find many examples from ALL worldwide DFI engine manifactures !
Greets ASH@IPF-TUNING