Variable Valve Timing Solenoid: Service and Repair

Camshaft timing control, testing
The timing of the intake camshaft is controlled according to engine load and engine speed. The electrically operated solenoid valve for camshaft adjustment transmits oil pressure to the mechanical camshaft adjuster as required.

Note: The camshaft timing control only becomes active 25 seconds after engine is started.

Testing system

Special tools and equipment
^ VAS 5051 and VAS 5051/1

Requirements for test:
^ Coolant temperature at least 80°C
^ Vehicles with automatic transmission: selector lever in position P or N

Test sequence
- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" from menu. When doing this engine should be idling.

WARNING!
^ Test equipment must always be secured on rear seat and operated from rear seat by a second person.
^ If test equipment is operated from front passenger seat, occupants could be injured by passenger's airbag in an accident.





Display on VAS 5051:
- Select diagnosis function "04 - Basic settings" from menu -1-.





Display on VAS 5051:
1 - Enter display group
- Using keypad -2-, enter "094" to select Display group 094 and confirm entry with (arrow) button.





Display on VAS 5051:
- Press button -A- to activate Basic setting.
- Increase engine speed to above 2000 rpm for about 10 seconds.
- Check readouts in display zones -3- and -4-.





If specification "Syst. O.K." is not attained:
Press the (arrow) button twice.





Display on VAS 5051:
- Select diagnosis function "08 - Read data block" from menu -1-.





Display on VAS 5051:
1 - Enter display group
- Using keypad -2-, enter "090" to select Display group 090 and confirm entry with (arrow) button.








Display on VAS 5051:

Test requirement:
^ Engine idling.

- Check readouts in display zones -3- and -4-.





- Take vehicle for a test drive.
- Check readouts in display zones -3- and -4-.





- Press the (arrow) button to exit from function "08 - Read data block".

If specifications are not obtained:
- Test solenoid valves for camshaft adjustment.

Note: If only a value between 6.0° cr/shaft and 16.0 "cr/shaft is displayed during test, electric valve for camshaft adjustment is correctly transferring oil pressure to mechanical camshaft adjuster, but mechanical adjuster cannot reach its end position (for example, because it is not moving freely).