Intake Manifold Change-Over Function, Checking

Intake Manifold Change-Over

Intake Manifold Change-Over Function, Checking
This test should only be performed if there is a performance deficiency.

The intake manifold switches from the long intake path to the short one at approx. 4700 RPM.

- Increase engine RPM significantly above 4700 RPM. This process should actuate the vacuum diaphragm for the intake manifold change-over. (Component location: on intake manifold front left, beneath ignition coils).

If the change-over does not occur, the following tests must be performed.
- Check Intake Manifold Change-Over Valve -N156-, if necessary, check activation valve. Refer to "Scan Tool Testing/Output Diagnostic Test Mode (DTM) (Function 03)", Testing and Inspection
- Check vacuum system for proper seal. Refer to "Vacuum System, Checking For Proper Seal", Testing and Inspection
- Check vacuum lines for proper connection, sealing and continuity.
- Check whether the change-over mechanism moves easily (operate change-over linkage by hand).