volkswagen Workshop Repair Guides

Volkswagen Workshop Service and Repair Manuals

ABOUT US
Checking charge pressure control solenoid valve N75 > < Engine code AGR

Golf Mk4

Engine code AHF, ALH, ASV
Engine code AHF, ALH, ASV
Test prerequisites
l  No fault stored in fault memory → Rep. Gr.01
l  No leaks on intake and exhaust systems
l  No faults in engine and fuel injection system, e.g. commencement of injection, injectors and compression pressure.
l  Engine oil temperature at least 80 °C
Test procedure
Note the following if testers and measuring instruments have to be used during a road test:
t  Test and measuring instruments must always be secured to rear seat and operated by a second person from this location.
If test and measuring instruments are operated from front passenger seat and the vehicle is involved in an accident, there is a possibility that the person sitting in this seat may receive serious injuries when the airbag is triggered.
–  Connect fault reader -V.A.G 1551- or vehicle diagnosis tester -V.A.G 1552- with cable -V.A.G 1551/3- and select engine electronics control unit with “address word” 01. The engine must be at idle when doing this: → Rep. Gr.01
   
Indicated on display:
–  Press keys 0 and 8 for “Read measured value block” function and confirm with Q key.
  
Rapid data transfer                 HELP
Select function XX
Indicated on display:
–  Press keys 0, 1 and 1 for “Display group number 11” and confirm entry with Q key.
  
Read measured value block           HELP
Input display group number XXX
–  Indicated on display:
–  Accelerate vehicle in 3rd gear from approx. 1500 rpm using full throttle.
–  At approx. 3000 rpm, press PRINT button on fault reader -V.A.G 1551- or vehicle diagnosis tester -V.A.G 1552- .
  
Read measured value block 11         ->
840 rpm    938 mbar   978 mbar   92%
Specification on fault reader -V.A.G 1551- or vehicle diagnosis tester -V.A.G 1552-: 1700…2250 mbar (in display zone 3)
If the specification is not attained:
–  Carry out final control diagnosis and actuate charge pressure control solenoid valve: → Rep. Gr.01
  
Read measured value block 11           ->
3090 rpm     1866 mbar    1917 mbar    62 %
Indicated on display:
The solenoid valve should operate and, when this happens, the wastegate pressure unit linkage should move back and forth on the turbocharger (at least 3…4 times, as long as there is vacuum in the vacuum reservoir).
–  If the rod moves and the charge pressure specifications are not obtained, renew turbocharger.
If linkage does not move because the solenoid valve is not working:
–  Check charge pressure control solenoid valve -N75- → Chapter.
–  Check vacuum hoses → Chapter.
If linkage does not move, even though solenoid valve is working:
  
Final control diagnosis               ->
Charge press control solenoid valve N75
–  Connect hand vacuum pump with accessory -V.A.G 1390- to charge pressure control valve and check linkage for freedom of movement.
–  If linkage does not move easily, renew turbocharger.
  N21-0078

Checking charge pressure control solenoid valve N75 > < Engine code AGR