Variable Induction System: Description and Operation
DESCRIPTIONThe air induction system improves engine performance by using the intake manifold runner control (IMRC) assemblies as follows:
- The intake manifold (9424) has two runners per cylinder, feeding each of the intake ports in the cylinder heads (6049).
- The IMRC is integral to the lower intake manifold. The assemblies are located between the upper intake manifold and cylinder heads, providing two air passages for each cylinder.
- One air passage is always available to direct throttle input and the other passage switches from closed to open by means of a valve plate, the intake manifold runner control actuator and cables.
- Below 2800 rpm, this valve plate is closed to improve low speed and cold engine performance.
- Above 3500 rpm, this valve plate opens to improve high speed engine performance.
The valve plates are opened and closed by the electric actuator and cable assembly, which is controlled by the powertrain control module (PCM) (12A650).