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

[Mike Claire]

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
> _______________________________________________
> S-CAR-List mailing list
> S-CAR-List at audifans.com
> http://www.audifans.com/mailman/listinfo/s-car-list
>
>