I had removed the intake to replace the clutch on my alternator. Many
folks over at the tdi forum go on and on about the clogging of the
intake so I looked at mine. I had some crud so I removed it, scraped
it, sprayed it with carb cleaner and pressure washed it. It looked
pretty clean when done. No performance difference though. I guess it
was not all that clogged. I was planning on installing a Mann Provent
to reduce all that oil from getting in the intake. If any of you have
removed the intake pipe you will see all the oil which may not be all
that much but ti does accumulate over time. There are even articles
that mention how to clean the intercooler of this oil mess.

My theory is that the oil from the crankcase vent mixes up with the
egr gasses and the heat of the turbo to make some nasty coke or soot.
Removing the oil from the mix should reduce that build up. I need to
purchase a good vent to test my theory. Unfortunately it takes me
about 3 years to accumulate 100,000 miles.

One myth proposed is that reving the engine will prevent these
deposits. I generally drive for mileage getting 50 mpg regularly.
Reving over 3,000 is rather rare and I generally shift at 2,000. I
feel this is a myth because an engine is more often than not runnng at
relatively steady states at relatively low rpms with relatively low
boost. Second thought is that you have more crankcase pressure at
higher revs. More pressure might mean more oil slung about that gets
into the intake gunking stuff up. My third part of this is fluid
dynamics. There are areas of high velocity and low velocity in an
intake. You will get some deposits in areas of low velocity no matter
how much you rev.

Some propose egr recalibration which apparently has drwawbacks like
reduced power and reduced mileage. I believe I read that the computer
makes some calibration related to the egr that reduces fuel flow.

Has anyone seen any good studies from a well educated mechanic or
other source that might shed light on the oil-egr interaction?

Jim B.