Re: Berzerk pressure transducer -Reply

[Dave Head <dhead@sundial.net>]

At 02:49 PM 6/19/97 -0400, you wrote:

>I've been having similar weirdness on my 91 200qw (IA stage 3) along
>with a problem getting max boost.
>The relative scale is usually  .4 off throttle coasting and highest is 1.7 to
>1.8.  But I have seen as low as .2 when coasting and 1.1 full throttle
>(max boost limited).  Sometimes when it seems I'm about to be
>boost-limited, I get some misfiring at high boost levels.  Something is
>definitely not happy under there.  When really cool, it runs pretty well.

Under normal conditions I'll see .2-.1 during engine braking, .3 at idle,
.3-.4 with medium fan running, .5 with AC on. When it works right (until
today) its accurate to within .1-.15 bar...

My misfiring at high boost has alway ended up being a bad hose/vacuum
leak/air leak...

>Mine seems to be relative to the outside temp and/or how warm things
>are in the engine compartment.  When temps are high, I won't get full
>boost.  This happens if I sit in traffic for a while or if the cars has only
>been shut down for a short time and restarted.  I noticed this behavior
>first during my cross-country trip.  When I would pull off the interstate to
>get gas, then get back on, I would not have full boost for "merging" :-).
>After a few miles apparently things would cool enough and I could get
>max boost again.  

Many times these leaks are temperature dependent - especially on Audis...
Those underhood temps can be evil...

>This behavior seems to be getting worse and although the car still has
>adequate power, it obviously needs some attention.  You caught my
>attention with this one because of singling out the pressure transducer. 

>That is on part of the IA mod I have; the pressure transducer is changed.

Is it a 2.5 bar transducer?

>I haven't started to troubleshoot this yet because of time constraints.  I
>am also waiting until I get my other car down here so I have alternate
>transpo in case I really screw somehting up poking around in there. :-)

Someone else should be able to give you the pinout - yer ECU is diffent than
mine. Pin 17 is supposed to give the reading for the transducer output on
mine - 4.9 to 5.0V at 1.9 - 2.0 bar.
********************************AUDI FAN***********************************
                                   EMCM(SW) Dave Head  
87 5KCStq 194K miles                1.7 bar 
    qcusa #3442                 Maitland, Florida   
******************************************************************************