Intake Manifold Change-Over Checking

Intake Manifold Change-Over, Checking

NOTE: The intake manifold switches from the long intake path to the short one at approx.5400 RPM.

Intake Manifold Change-Over, Checking Function

NOTE: The following test should only be performed if there is a performance deficiency.

- Increase engine speed to noticeably above 5400 RPM.
Specified value: Vacuum diaphragm for the intake manifold change-over must activate.

If vacuum diaphragm does not activate:
- Check vacuum lines for proper connection, sealing and continuity, see overview of Intake Manifold Change-Over.
- Check whether the change-over mechanism moves easily. (Operate change-over linkage by hand as a test).
- Check-valve (black/white) leaky, clogged or incorrectly installed.
- Intake Manifold Change-Over Valve faulty (does not switch through or clogged).
- Check Intake Manifold Change-Over Valve -N156-. Testing and Inspection
- Check vacuum system for proper seal.
Vacuum System, Checking For Proper Seal