Vacuum Leak/Boost Issue

Ben Swann benswann at
Mon Mar 23 19:06:24 PDT 2009

It does does of sound like the pressure transducer or ECU circuitry  is bad.  When
engine not running readout should be 1 ( or .9 if at higher altitude or low pressure

P.T. in ECU does provide the output to the dash readout.  You might want to install a
guage to erform a sanity check.

I suppose you could swap in a good known working ECU - if you need one LMK.


[Date: Mon, 23 Mar 2009 09:43:51 -0400
From: "Hayes Myers" <hayesmyers at>
Subject: Vacuum Leak/Boost Issue
To: <quattro at>
Message-ID: <004f01c9abbd$682120e0$386362a0$@com>
Content-Type: text/plain;	charset="us-ascii"

Started tracking down the running issues on the 10v: 

Trying to track down low boost issue. My dash boost indicates .4 or .5
(should be .9/1 when you turn the key even). Ran lots of quick start trying
to find boost leak. pulled intercooler off, checked hoses, put a known good
intercooler on. Didn't find anything doing these leak checks. Ran compressed
air through the ECU vacuum hose and heard what sounded like an air tank
filling up from under the hood. no whooshing /leak noises.  When pulling the
vacuum cap off the top of the fuel distributor boot (i think that's what it
is called) nothing happens...runs happily along... which seems strange. I'm
running right now with the vacuum hose off the ECU (plugged this hose with a
screw/clamp). Still get same dashboard reading and car runs exactly the
same. I'm thinking the transducer in the ECU may be shot among other things.

1) Do you tink the transducer will affect things? (does the pressure reading
give the ecu a signal other than the readout..i'm imagining it might)
2) where else would i be leaking?? Feel that the intake side is in good
shape. (even swapped mm hose).

Feel like i'm getting closer to a solution... looking forward to having

Hayes Myers, P.Eng   

91 200 TQM 10v]

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