[s-cars] Boost gauge not functioning / How do I pressure test intake?

[Walsh, Edward]

I just installed a boost gauge that is T'd off the manifold vacuum line that
activates the bypass valve.  The same place that I used successfully on a
previous S4.

Well, the gauge wouldn't show boost or vacuum. The needle doesn't move.  The
gauge works as tested w/ mityvac.  So I tested the bypass valve itself by
applying suction to the port.  Sure enough, it wouldn't hold vacuum.  Oddly,
though, I would hold pressure (I couldn't breath out).  Would a blown bypass
valve create a leak large enough to prevent the gauge from working?  Or, do
I have another leak elsewhere in the system?  I did try to "pressurize the
system by applying 10psi via compressed air to the hose II plumbed in for
the boost gauge, and the system would hold no pressure.  The air would
quickly leak out in a non-descript area/manner.  Did I test the system
properly?

Thank you for any insight,

Ed


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