Intake Manifold: Testing and Inspection

Intake manifold change-over, checking

Engine codes BDC, BGD
This check need only be performed when there is a reduction in available torque, i.e. issues with engine elasticity and pulling power on acceleration etc.

Special tools, equipment, testers, measuring instruments and auxiliary items required

^ VAG1390 Hand vacuum pump

^ VAG1368 Vacuum tester

Work sequence
^ Check that vacuum lines are correctly installed and not interchanged.
^ Check vacuum hoses for porosity.
^ Check vacuum system for leaks.

Checking vacuum actuator in intake manifold upper part for leaks

^ Pull vacuum hose to variable intake manifold actuator (arrow) off intake manifold change-over valve -1-.

Note: The variable intake manifold change-over actuator is integrated in the manifold and is therefore not visible from the outside.

^ Connect hand vacuum pump VAG1390 to vacuum tester VAG1368 (connection -B-).

^ Pull vacuum hose to variable intake manifold actuator (arrow), off intake manifold tuning valve -1-.
^ Connect hand vacuum pump VAG1390 to vacuum tester VAG1368 (connection -B-).

^ Connect vacuum hose (to actuator) to vacuum tester VAG1368 (connection -A-).
^ Set vacuum tester to -A/B- position.
^ Operate VAG1390 several times. Create a vacuum of maximum 500 millibar.
^ Vacuum must not drop

If the vacuum drops:
^ Replace intake manifold lower part.

If the vacuum does not drop at either of the vacuum actuators:
^ Check change-over mechanics in intake manifold for freedom of movement.
^ Remove intake manifold upper part.
^ Repeat leak tests on both vacuum actuators. Check that change-over flaps move.
If fault is detected:
^ Replace intake manifold upper part or intake manifold lower part.