Camshaft Timing Control, Checking

Camshaft timing control, checking
The intake camshaft is adjusted as a function of load and engine speed. The camshaft adjustment solenoid valve switches oil pressure to the camshaft adjuster (mechanical adjustment device).

Note: Camshaft timing control only becomes active 25 seconds after starting engine.

System test, performing
Special tools and equipment





^ VAS 5051 with VAS 5051/1

Test requirements:
^ Coolant temperature at least 80°C
^ Selector lever set to P or N

Work sequence
- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01- Engine electronics" from list. Engine must be idling.

WARNING:
^ Always attach testers and measuring instruments to back seat and have them operated from there by a second person.
^ If testers and measuring instruments were to be operated from front passengers seat, person sitting there could suffer injury in the event of an accident due to triggering of front passengers airbag.





Indicated on VAS 5051:
- From list -1- select diagnostic function "04- Basic setting".





Indicated on VAS 5051:
1. Enter display group
- Use keypad -2- to enter "094" for "Display group number 094" and confirm by touching Q key.





Indicated on VAS 5051:
- Activate basic setting by touching key -A-.
- Simultaneously press accelerator and brake pedal; engine speed increases to approximately 2200 rpm.

Condition:
^ Accelerator and brake pedal pressed simultaneously, engine running at approximately 2200 rpm





- Check specifications in display zones -3- and -4-.
If reading does not match "Syst. OK' specification:
- Touch 4 key twice.





Indicated on VAS 5051:
- From list -1- select diagnostic function "08- Reading measured value block".





Indicated on VAS 5051:
1. Enter display group
- Use keypad -2- to enter "091 " for "Display group number 091 " and confirm by touching Q key.





Indicated on VAS 5051:
- Check display in zones -3- and -4- at idle and in the course of a test drive.
- Perform the same test in display group 092.
- Touch s key or t key to switch display group.
^ Actual value in display zone -4- must roughly correspond in each case to specification in display zone -3-
- Terminate function "08- Reading measured value block" by touching < key.

If actual value does not match specification:
- Check camshaft adjustment solenoid valves; Refer to Camshaft adjustment solenoid valves, checking

Note: If value displayed during test drive is far too low, solenoid camshaft adjustment valve is switching oil pressure properly to mechanical camshaft adjuster, but adjuster is not able to attain its end position (e.g. stiff).