Doesn't make any sense to me. I am going to try to get a hold of a tech I worked with in the next week or two to see what they say causes it. If it's something simple such as diverting an intake/exhaust path, that'd be a relief.

 

^I can't believe I didn't think of this one - crank case ventilation. People seem to be using oil catch cans... So I would assume it could be a ventilation issue. Thinking out loud, my guess is venting the crank case to atmosphere would solve the issue. Wonder how you do that on the 4.2?

Seems EGR could be an issue as well. From Audizine, a post on VWAG's patent:
http://www.audizine.com/forum/showth...=1#post4752426
So if there is EGR, do a delete, vent the CC to atmosphere or employ a catch can.

 

Meth injection, catch can does not work. Everything has been tested.

Its not exactly carbon from combustion, its oil film buildup thats not effectively cleaned by fuel since the engine is direct injected, not port injected. It affects airflow dramatically into the motor causing power loss. VAG motors have not used EGRs since the early 90's.

 

Though I could be wrong, my experience would tell me the fact it is direct injected should not be the issue - plenty of DI motors are spotless on the intake side of the head - what is allowing the oil to get onto the intake side of the head? Bad sealing at the valve and head? Crank case ventilation?

 

I've never seen a DFI injected Porsche engine have this issue.

 

The oil vapor in the air stream clings onto the valves and stays there because the valves are relatively hot on the heads. The RS4 already has an elaborate crankcase ventilation system equipped with a 3 stage venturi cyclone to help remove the oil particles. Obviously it doesn't separate all the oil out otherwise this wouldn't happen.



There already is a cyclonic oil separator in these engines that is a bit more advanced than a catch can and works much better. There is nothing more efficient in removing oil from the PVC system than that. But, a cyclonic separator cannot remove volitile oil components that remains in the vapor stage. Fuel dilution can drive flashpoint down in the mid 200F range in these engines, which is the operating oil temperature.



Basically fuel dilution is the cause of this issue on these motors.

Possibly preventing this is to vent crankcase pressure out to the atmosphere rather than back into intake but in that case need to cap off the source of crankcase vacuum so you don't have vacuum leak which can cause other headaches.

 

Ok, then how do we prevent fuel blow-by?

Allow the engine to come to temp before increasing load or RPMs?

Change the oil frequently?

 

Kai,

By fuel dilution I'm guessing you mean oil blow-by is getting into the fuel in the combustion chamber then the crankcase vapor (composed of both oil and fuel) is gumming up the intake ports?
I think what Kai is suggesting is to vent the crank case to the atmosphere. You'll have to plug the device that creates the vacuum for the CCV system as it is a NA engine. Changing the oil will not help blow-by as blow-by is created by oil blowing past the piston rings into the combustion chamber.

Fuel blow-by would mean fuel is getting into the oil.