Overboost and diaphragm

[Bruce Kaye <bruce.kaye@edrd.dnd.ca>]

Hello to all

The Audi gods have requested an offering.  I was driving up a long grade
and I moved over to pass a slow car in the fast lane when suddenly the
wagon stumbled. It was the like I had run out of gas...?  The next time it
happened, I was accelerating up the highway and I noticed the boost gauge
climbing to 1.6 bar then - the wall. The fuel pump shutoff kicked in.(this
only happens in 4th and 5th)  So now I think I know the problem and I need
help with the cause and fix.  My mechanic's first thought is a torn
wastegate diaphragm but he hasn't seen the car yet.  After a quick search
of the archives I  found the following probabilities; torn diaphragm,
broken tube to the bottom of the wastegate, stuck wastegate and bad
pressure sensor.  Are there any others and where can I get a new wastegate
diaphragm?  

Thanks in advance. This list make it possible to own an Audi and not have
to win the lotto. 



Bruce 

87 5000CD Quattro Avant
87 5000s Avant (parts?/fixer-upper)
86 5000s Avant (wife's)
83 GPZ 1100
75 TR6