[s-cars] Question about turbo chatter and BPV

[Trevor Frank]

I don't think it should make this noise. This sounds like turbo stall
due to backpressure on the turbo.  I have seen the bpv's installed
backwards and it has lead to this.  I have also seen more installs where
there was too much spring pressure used and the same was true.  I
personally have done both in the past and have been corrected by other,
Javad, Chris L, thanks that I had screwed up.  I have heard that when
they are torn they make a bit of a brrrrr sound around 3k.

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com] On Behalf Of James Bufkin
Sent: Sunday, July 18, 2004 6:46 AM
To: s-car-list at audifans.com
Subject: [s-cars] Question about turbo chatter and BPV

I don't own a urS4, but a good friend of mine does and I helped him
install
a Stage 1 pair of chips yesterday morning.  The chip install went fine
and
the 287 HP was definnately there, but when I sat in his car and we went
for
a test drive, I was hearing a definate turbo chatter at the top of the
revs
between shifts.   I could especially hear it when driving next to parked

cars or concrete barriers.

I told him I think his BPV is faulty cause that noise is indicative of
turbo stall, just like the rally cars used to make (I really like the
sound, but its not good for a street car in the long scheme).   He said
his
car has been making that noise for a year or so.   Good thing the guy
rarely takes his car about 4K rpm when he's driving...     So we went
back
to my place and removed the BPV, It looked okay.   There was a trace of
oil
on the side facing the turbo, which was odd, but could be explained by
the
fact we were pushing the motor to test the chip.   The vacuum line to
the
Valve was intact as well.

Is the only possibility a torn boot inside the BPV?

James



----------------------------------
James Bufkin, P.E.
Bufkin Design & Engineering, Inc.
Austin, Texas
ph: 512-236-8070
fax:  512-480-5927
cell:  512-914-2659

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