Variable Induction System: Description and Operation

The air intake system utilizes a secondary intake port along with a primary intake port. The secondary port is opened and closed by an electronically operated intake manifold runner control (IMRC) deactivation motor, thus improving low and mid-range torque and fuel efficiency.

The air induction system improves engine performance by using the intake manifold runner control (IMRC) assemblies as follows:

- The intake manifold has two runners per cylinder, feeding each of the intake parts in the cylinder heads.

- The IMRC assemblies are located between the intake manifold and cylinder heads, providing two air passages for each cylinder.

- One air passage is always open and the other passage switches from closed to open by means of a valve plate.

- Below 3000 rpm, this valve plate is closed to improve low-speed and cold engine performance.

- Above 3000 rpm, this valve plate opens to improve high-speed engine performance.

The valve plates are opened and closed by the IMRC deactivation motor, which is controlled by the powertrain control module (PCM).