Variable Induction System: Testing and Inspection

Intake Manifold Change-over, Checking

Testing should only be performed if the engine is losing power.
The intake manifold change over function switches over from the long intake tract to the short intake tract at about 4200 rpm.

Intake manifold change-over, checking function







- Remove front engine cover (arrows).







- Start engine and increase engine speed to well above 4200 rpm.
- The operating rods of the actuator for the intake manifold (arrow) must move.

If the change-over is not taking place, perform the following tests:

- Check intake manifold change-over valve -N156- (perform final control diagnosis, if necessary, check valve and actuation).
Output Diagnostic Test Mode (DTM) (Function 03)
Testing and Inspection
- Checking vacuum system for leaks. [1][2]Testing and Inspection
- Check that vacuum hoses are properly connected and free of leaks and obstructions.
- Check that change-over mechanism operates freely (move push rod by hand).