[s-cars] Boost leak - update, what am I missing here?

[Mike Claire]

Thanks for jumping in guys.  All dead ends so far and there's no way forward
until I take care of the one big blind spot I still have.

I've only tested the plenum to 15.  I need to go higher but that MAF to
turbo hose was about to blow.

Next time I'll start at the turbo output and give it 25 and we'll see what
happens.  Anybody know what to use there as a compressor test plug?

BTW when the car was idling a few minutes ago I put my palm over the exhaust
tips and it was pulsing along with each cylinder.  I read someplace that
blocked cats will give you a slow, steady ultrahot exhaust.


Mike


On 4/21/07, Mike Claire <mike.claire at gmail.com> wrote:
>
> Yes, on test #4 I removed the input line from the wastegate.  And I
> expected unlimited boost and all I got was the same old 15 or 16 lbs.
>
> My conclusion was the same as yours - I must have a massive leak or a bad
> turbo.
>
> Next test will be removing the samco from the turbo outlet, finding a plug
> that I can put a compressor quick connect on, and pumping 25 lbs into it.
>
>
>
> Mike
>
> On 4/21/07, calvinlc at earthlink.net <calvinlc at earthlink.net> wrote:
> >
> > On test #4, if you removed the input line to the wastegate you should
> > have
> > seen basically unlimited boost if you kept your foot in it, if I am
> > thinking
> > about it right.  If you did not see tons of boost with that hose
> > disconnected I think you may have a turbo problem or a massive leak.  Am
> > I
> > remembering this plumbing right?  I have a tendency to get mixed up
> > between
> > the 10 valves and the 20 valves here as they reversed the plumbing to
> > the
> > WG.
> > --Calvin
> >
> >
> > -----Original Message-----
> > From: s-car-list-bounces at audifans.com
> > [mailto:s-car-list-bounces at audifans.com ]On Behalf Of Mike Claire
> > Sent: Saturday, April 21, 2007 12:57 PM
> > To: S-car list
> > Subject: [s-cars] Boost leak - update, what am I missing here?
> >
> >
> > A bunch of you guys replied to me last week with ideas, and I appreciate
> > the
> > help.  I've gone through everything suggested, and have read everything
> > about these issues I could find on Scott Mockrey's site,and STFA with
> > abandon.  I'm pretty much tapped - nothing to show for it.  I was
> > distracted
> > this week by new symptoms - and ultimately #3 coil just failed entirely.
> > Dead short.  That's fixed now and the car runs great again - except it's
> > still low on boost.
> >
> > (subject is a '93 S4, MTM 1+ (Pastore) chip.  Used to indicate 22 lbs on
> >
> > A-pillar gauge.  Now it peaks at 16 or 17, and backs down from there.)
> >
> > I'm either losing boost - or not making enough of it.  I don't know
> > where
> > else to look - what am I missing here?
> >
> > 1.  Pressure tested main intake plenum to 15 lbs with a compressor and
> > PVC
> > cleanout plugged into the intake boost.  Closed off Samco where it
> > enters
> > the intake, and the ISV - PASSED
> >
> > 2.  Pressure tested all the small hoses in the PCV circuit, water trap,
> > ECU
> > connection, boost gauge connection, etc. etc.  PASSED
> >
> > 3.  Removed BPV, plugged the Samco, plugged vacuum line (eliminate
> > possibility of BPV leaking pressure).   PASSED
> >
> > 4.  Removed silicone line from wastegate, plugged it shut (to test for
> > possibility of wastegate opening prematurely)  PASSED
> >
> > I can only think of two possibilities - either the turbo is no longer
> > capable of building normal boost, or the intake plenum is leaking at
> > pressures higher than 15 lbs.
> >
> > Could the turbo be failing?  It sounds the same and drives the same as
> > ever
> >
> >
> > I can take the Samco off the turbo outlet and pressure test from there,
> > but
> > I don't have compressor plug handy for that.
> >
> >
> > Before I do that - any ideas?
> >
> >
> > Mike
> > _______________________________________________
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> >
> >
>