A200 20V 3B / Motronic Fault / Engine s

[arnberg@NCSMSG01ES.ntc.nokia.com (Arnberg Tommy NTC/MSG-Es)]

Hello !

Car:            Audi 200   20 V   3B  Turbo  engine  -90

Problem:  Annoying ping/knocking  problem.
                    It seems that  the  Knock sensor system works,   but 
reaction time is slow.
                    How slow is fast enough ?
                    Mileage is also  worse than factory value;  about 1,5  L 
  more  per   100 km.
                    Mileage tested with  warm enough engine and  temperature 
and  friction OK

Conditions:   1B  engine swapped   to   3B   engine
                         4 or 5  gear
                         RPM  around  1700  1800
                         pedal pushed to metal and boost builds up
                         98 octane O2 - oxinated  bleifrei super gas, 
strongest available
                         spark plugs:  BRISK  premium  trispark  according 
to plug mf.    OK
                         spark leads OK
                         fuel rail operating pressure OK
                         fuel delivery rate OK
                         lambda sond values OK
                         inleat air leaks   OK
                         wastegate frequency valve ohms   between  25 <-> 35 
   OK

Foundings:   I visited local ( very few good available)  BOSCH
                         Center and   result:
                          Motronic  error  code  00513 /  2111   Engine 
speed sender (G 28) / Problems ?

 - what could be wrong with the sensor system  ?
 -  what could be the most likely problem / solution ?
 - I have not yet done  the speed  sensor    wire ohm  test   1  <-> 2 
   about    1 kohm
  1 to 3      and        2 to     3     infinite
 - how does  Motronic  judge,  that   the speed sensor  is not OK ?

rgs.
Tommy Arnberg
FINLAND