Variable Induction System: Description and Operation

PURPOSE:
To create high torque at low rpm range, requires a long intake pipe with a small diameter. To achieve high performance in the upper rpm range a short intake pipe with large diameter is required. To achieve a compromise, an intake manifold change-over was developed at an rpm of approximately 3950. The intake paths in the intake manifold change-over are shortened by opening the change-over doors. Intake manifold change-over is activated by a valve.
OBD II CHECKS:
The electrical function of the valve.

Intake Manifold Change-Over Valve N156:

Electrical Circuit - Intake Manifold Change-Over Valve N156:

Intake Manifold Change-Over Valve N156:
The valve is located next to the EGR-frequency valve on the mass airflow sensor. If there is a break in the circuit, the change-over doors remain closed.