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Checking charge pressure regulation solenoid valve N75 > < Checking charge pressure system: engine code AWC

Leon Mk2

Checking charge pressure regulation
Checking charge pressure regulation
Special tools and workshop equipment required
t  Fault reader -V.A.G 1551-
t  Diagnosis cable -V.A.G 1551/3C-
  Note!
The vehicle system tester -V.A.G 1552- can be used instead of the fault reader -V.A.G 1551-, however a print-out is not possible.
Test prerequisites
l  No fault may be stored in fault memory → Rep. Gr.01.
l  Engine oil temperature at least 80 °C (radiator fan must have run once).
l  No leaks on intake and exhaust systems
Test procedure
–  Connect fault reader -V.A.G 1551- (vehicle system tester -V.A.G 1552-). Start engine and select “Address word” 01 of engine control unit. Connect fault reader and select engine control unit → Rep. Gr.01.
   
Indicated on display:
–  Press keys 0 and 8 for function “Read measured value block” and confirm entry with Q key.
  
Rapid data transfer                 HELP
Select function XX
Indicated on display:
–  Press keys 1, 1 and 4 for “Display group number 114” and confirm entry with Q key.
  
Read measured value block               
Input display group number XXX
Indicated on display: (1...4 = display zones)
–  During a test drive or on the rolling road, check (at full throttle between 1800…2300 rpm) on-off ratio of charge pressure control solenoid valve -N75- in display zone 4. Specification: 5.0…95.0%.
Observe applicable safety precautions during road test → Chapter.
If the specification is attained:
–  Change to display group 115 as follows: fault reader -V.A.G 1551-: press key 3 vehicle system tester -V.A.G 1552-: press key ↑.
  
Read measured value block 114          ->
         1         2         3         4
Indicated on display: (1...4 = display zones)
–  Check actual charge pressure value in display zone 4 at full throttle:
On rolling road
In 3rd gear or 2nd gear (automatic)
During vehicle operation
Vehicles with manual gearbox
–  In 2nd gear, accelerate vehicle at full throttle.
Vehicles with automatic gearbox
–  Manually engage 4th gear (automatic) and accelerate the vehicle at full throttle from a low speed (without kick-down, the gearbox no longer shifts down).
–  Press print key between 1800…2300 rpm and read off actual charge pressure value in display zone 4. Specification: 1350 … 1750 mbar.
–  Compare actual charge pressure value with specification in display zone 3. Max. difference: 100 mbar.
  Note!
Repeat test if full charge pressure has not yet built up or difference between specified and actual value is excessive.
–  Press the → key.
–  Press keys 0 and 6 for function “End output” and confirm entry with Q key.
–  Switch off ignition.
If the charge pressure is exceeded:
–  Check charge air pressure sender -G31- → Chapter.
–  Check charge pressure control solenoid valve -N75-. (Vacuum hose from turbocharger via solenoid valve to vacuum unit not blocked when connector is pulled off).
Vacuum hoses on solenoid valve → Fig..
–  Check that vacuum unit for charge pressure control valve is securely mounted on turbocharger.
–  Check vacuum unit for charge pressure control valve → Chapter.
If the charge pressure is not attained:
–  Check charge air pressure sender -G31- → Chapter.
–  Check charge pressure regulation solenoid valve -N75- → Chapter.
–  Check vacuum unit for charge pressure control valve → Chapter.
–  Turbocharger defective. Renew turbocharger → Chapter, Removing and installing turbocharger with attachments.
–  Interrogate and erase fault memory → Rep. Gr.01
  
Read measured value block 115          ->
         1         2         3         4

Checking charge pressure regulation solenoid valve N75 > < Checking charge pressure system: engine code AWC