MB CIS system - more questions

[quk@sievers.com (Phil Payne)]

OK, guys - pay attention:
 
a) WOT switch - Bosch 0 280 120 308, Audi 034 133 093F
 
   Is it normal to see hysterisis?  It makes, and then you can back off
   10 to 15 degrees before it breaks.  Also, is this the part that people
   have been cheerfully dismantling and fixing?
 
b) Pressure regulator (membrane valve) - 034 133 534L
 
   I ran a normal check on the warm-up regulator.  Despite Charles Probst's
   comments about "control pressure regulator" being a more acceptable term
   than "warm-up regulator", I think the lattr term is better on the MB 
   because it has no vacuum-controlled functions.  Anyway, it warmed up fine.
 
   With the engine idling at a control pressure of 3.5 bar, I tried feeding 
   vacuum into the membrane valve.  At 0.7 bar, it reduced control pressure
   by 0.2 bar.  This doesn't seem to be very much.  So the question - how
   much does the vacuum link to the warm-up regulator reduce control 
   pressure on cars that do it this way?
 
I still can't find any data on the membrane valve's nominal performance, and I 
can't discover any part number for the frequency valve (which the microfiche 
refers to as the control valve). 

--
 Phil Payne
 phil@sievers.com
 Committee Member, UK Audi [ur-]quattro Owners Club