Intake Manifold Runner Control (IMRC) Solenoid

Fig 1: Intake Manifold Runner Control (IMRC) Solenoid

Courtesy of GENERAL MOTORS CORP.

The characteristic torque curve of a normally aspirated engine depends mainly on how the engines average pressure changes over the engine speed band. The average pressure is proportional to the volume of the air mass present in the cylinder when the inlet valve is closed. The design of the inlet system determines how large an air mass can be drawn into a cylinder at a given engine speed.

An intake manifold runner control (IMRC) valve (2) is used to change the intake manifold runner configuration. When the IMRC valve is open, the intake manifold is configured to one large plenum (4). When the IMRC valve is closed, the intake manifold is configured to two smaller plenums (3). The two intake manifold runner sizes result in different torque curves which improves performance at low and high engine speeds. The IMRC valve is located in the intake manifold (1). The ignition voltage circuit and the IMRC control circuit are routed to the IMRC solenoid thru an IMRC driver module. The IMRC driver module is an amplifier that is used to strengthen the IMRC solenoids ability to remain in the position commanded by the engine control module (ECM), during high load and current demands.