Checking turbocharger and charge pressure control: Audi A8 D2 (AFB, AJK, AKE, AKF, …)

🧭 Before you start

Fits: Audi A8 D2 (4D)

• Renewed: turbocharger

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• At altitudes above 1000 m, the difference between the two display zones may increase by 100 mbar for each further 1000 metres of altitude.
• The absolute pressure displayed on the turbocharger testerV.A.G 1397 A must decrease by the specified values stated.
• Check movement of linkage over entire adjustment range: It must move constantly and smoothly
• The absolute pressure displayed on the turbocharger testerV.A.G 1397 A must decrease by the specified value stated.

🔧 Engine codes this applies to

📋 Procedure

1. From list (1), select function "“08 - Reading measured value block”".
2. Use keypad (2) to enter "“033”" for "“Display group 033”" and confirm by touching Q key.
3. Increase engine speed to 3050 … 3150 rpm and maintain at this level until displays in zones (3) and (4) have settled.
4. Compare display in zones (3) and (4).
5. Check vane adjustment at both turbochargers (see the separate procedure).

6. Touch ← key.
7. Use keypad (2) to enter "“011”" for "“Display group 011”" and confirm by touching Q key.
8. Increase engine speed to 3050 … 3150 rpm and maintain at this level until displays in zones (2) and (3) have settled.
9. Compare display in zones (2) and (3). [Note: At altitudes above 1000 m, the difference between the two display zones may increase by 100 mbar for each further 1000 metres of altitude.]
10. Terminate function "“08 - Reading measured value block”" by touching ← key.
11. Check charge pressure (see the separate procedure).
12. On vehicles with auxiliary heater, screw out bolts (arrows) for attaching exhaust pipe of auxiliary/supplementary heater to noise insulation.
13. Unfasten quick-release fasteners (1) and (2) and detach front and rear noise insulation.
14. From list (1) select function "“04 - Basic setting”".
15. Use keypad (2) to enter "“033”" for "“Display group 033”" and confirm by touching Q key.
16. Activate basic setting by touching key A.
17. Check display in zones (2), (3) and (4).
18. Also check whether operating rods move alternately at both turbochargers (arrows).
19. Terminate function "“04 - Basic setting”" by touching ← key.
20. Check air mass meters (repair group 23).
21. Check linkage and vacuum units for charge pressure control (see the separate procedure).
22. Check vacuum actuation for left and right turbochargers (see the separate procedure).
23. Switch off ignition.
24. Switch on turbocharger tester V.A.G 1397 A and set measuring range switch to (I) (absolute pressure).
25. Attach measurement hose to connection (I).
26. Disconnect hose (arrow) at vacuum unit for charge pressure control.
27. Use test hoses to connect vacuum hand pump V.A.G 1390 and turbocharger tester V.A.G 1397 A as shown.
28. Use vacuum hand pump to generate vacuum.
29. Take vacuum reading on turbocharger tester V.A.G 1397 A.
30. In doing so, observe turbocharger linkage: [Note: The absolute pressure displayed on the turbocharger tester V.A.G 1397 A must decrease by the specified values stated.]
31. Vent the vacuum hand pump. [Note: Check movement of linkage over entire adjustment range: It must move constantly and smoothly]
32. Repeat test if necessary at second turbocharger.
33. Replace turbocharger.
34. Disconnect hose (arrow) at vacuum unit for charge pressure control.
35. Switch on turbocharger tester V.A.G 1397 A and set measuring range switch to (I) (absolute pressure).
36. Attach measurement hose to connection (I).
37. Connect measurement hose to vacuum hose detached.
38. From list (1) select function "“04 - Basic setting”".
39. Use keypad (2) to enter "“033”" for "“Display group 033”" and confirm by touching Q key.
40. Activate basic setting by touching key A. [Note: The absolute pressure displayed on the turbocharger tester V.A.G 1397 A must decrease by the specified value stated.]
41. Repeat test if necessary at second turbocharger.
42. Check whether charge pressure control hose has become disconnected or is clogged
43. Check charge pressure control solenoid valve N75 or N274.
44. Terminate function "“04 - Basic setting”" by touching ← key.
45. Touch "“06 - End output”".
46. Switch off ignition.

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