Not getting full boost and getting torque steer.

[Tony Guttmann <tonyg@ms.unimelb.edu.au>]

I'd like to thank members of this group for their invaluable
advice on my recent queries,  particularly Robert Myers, Daniel
Grady, Phil Payne and Scott Mockry's for his excellent site. I'd
also like to pass on my experiences in following up the suggestions
I received and - inevitably - ask for more help!

My car is an '89 200t - regretably non-quattro and even more
regretably automatic (but this was the only 200t that Audi imported
into Australia).

My first problem was torque-steer. A number of people suggested
replacing the top mounts of the front struts. I had thought of that
previously, but inspection from the top - and wiggling them with
a screwdriver - indicated that they were fine. However given the
almost universal view that they were likely to be the culprit, I
pulled one out, and found that it was split through from the bottom,
about 95% of the way to the top! So while it looked perfect from
the top, it was stuffed. I now await arrival of new mounts from
the States - where they are 1/4 the local price!

My other problem was lack of boost (only getting 1.3 bar max.). My
mechanic initially found that the turbo frequency valve wasn't
getting any signal. Checking out the codes - courtesy of Scott's
instructions - he got two error codes. One showed the air temp.
sensor wire o/c, the other indicated that the knock sensor on
cylinders 3/4/5 was not working. Fixing these problems raised
the boost to 1.4 bar, and the turbo frequency valve is now
working.

Also checked out the WOT switch. Circuit resistance in "wide
open throttle" measures as close to zero ohms as my multimeter
can read. Certainly less than 0.1 ohm - so I presume the switch is
fine. 

Tried replacing the ECU from another car. Still 1.4 bar. Tried
raising the octane rating of the fuel to 104. Still 1.4 bar.

There is a manifold pressure pick-up so my mechanic then arranged
some temporary plumbing to bleed off some pressure, thereby
falsifying the pressure to the ECU. This fooled the ECU into
signalling the frequency valve to stay open longer, and then I
got my 1.7-1.8 bar boost! So this indicates that the system can
get there - but how to make it do so?
 
Can anyone suggest what to try next? And/or tell me where I can get
operating voltages for various bits of the circuitry, or
resistance readings of various sensors, in order to determine 
which bit isn't sending the right signals?
 
Many thanks in anticipation of your help.

Tony Guttmann
-- 

phone +61 3 9344 5551, fax +61 3 9344 4599 
tonyg@maths.mu.oz.au 
http://www.ms.unimelb.edu.au