Intake Manifold: Testing and Inspection

Intake manifold change-over, checking
This check need only be performed when there is a reduction in available torque, i.e. problems with engine elasticity and pulling power on acceleration etc.

Test conditions

Special tools and equipment

^ V.A.G. 1390 Hand vacuum pump

^ V.A.G 1368 Vacuum tester

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

Check vacuum actuator in intake manifold upper part for leaks

^ Disconnect vacuum hose to variable intake manifold actuator (arrow) from 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 V.A.G. 1390 to vacuum tester V.A.G. 1368 (connection -B-).

^ Pull vacuum hose to variable intake manifold actuator (arrow), off intake manifold tuning valve 2 -1-.
^ Connect hand vacuum pump V.A.G. 1390 to vacuum tester V.A.G. 1368 (connection -B-).

^ Connect vacuum hose (to actuator) to vacuum tester V.A.G. 1368 (connection -A-).
^ Set vacuum tester to -A/B- position.
^ Operate V.A.G. 1390 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 a malfunction is detected:
^ Replace intake manifold upper part or intake manifold lower part.