Re: '88 5000CD TQW engine knocking

["Robert Myers" <rmyers@inetone.net>]

Don't think so, Frank.  A vacuum leak in this line will admit external air
into the system and should result in a reading near 1.0 bar, not zero,
unless the car is at quite high altitude.  Even then it is not going to
read even nearly that low.  

The problem just about has to be something strange happening with the
pressure transducer inside the ECU.  An intermittent open?  A short?  A
faulty transducer itself?  Or perhaps a break in the circuit to the
display?  (Don't think so - then the display should go blank rather than
low.)  Or...?

C'mon, Gurus, let's figure this one out for Andrew.

At 03:36 PM 2/12/98 -0800, you wrote:
>>Does anyone have the answer to this?
>>Intermittently, the digital boost guage will stop functioning and read
>>0.0, or 0.1
>>Once this happens, the engine will knock under hard acceleration
>>(pinging begins at about 3800rpm).  No warning lights come on.
>>When the boost guage is functioning properly everything is great!
>>        ???
>
>i would guess you have an intermittent vacuum leak in the line that goes
>from the mainfold to the computer..
>
>frank
>
>to: IN:andrew_ireland@scotia-mcleod.com
>cc: IN:quattro@coimbra.ans.net
>
>
___
   Bob
*****************************************************************
*  Robert L. Myers    rmyers@inetone.net      Home 304-574-2372 *
*  Rt. 1, Box 57                         FAX/Modem 304-574-1166 *
*  Fayetteville, WV 25840 USA            WV tag Q SHIP 2.2+ bar *
*  Obligatory quattro and sleddog-L references:                 *
*  My 3 Siberian Huskies enjoy riding in my '89 200TQ           *
*****************************************************************