Faulty Intake Manifold Runner Control (IMRC) actuator
Intake Manifold Runner Control actuator harness is open or shorted
Intake Manifold Runner Control actuator circuit poor electrical connection
Faulty Powertrain Control Module (PCM)
Engine Light ON (or Service Engine Soon Warning Light)
The Intake Manifold Runner Control (IMRC) is an electrically actuated system consisting of a motorized actuator with an attaching linkage for each housing on each bank. The linkage attaches to the housing butterfly plate levers. Each IMRC housing is an aluminum casting with two intake air passages for each cylinder. One passage is always open, and the other is opened and closed with a butterfly valve plate. The housing uses a return spring to hold the plates closed. The motorized actuator houses internal switches to provide feedback to the Powertrain Control Module (PCM), indicating linkage and plate position. Under about 3000 rpm, the vacuum solenoid will be energized. This will allow the manifold vacuum to be applied and the butterfly valve plates to stay closed. Above approximately 3000 rpm, the vacuum solenoid will be de-energized. This will allow a vacuum to vent from the actuator and the butterfly valve plates to open. The Diagnostic Trouble Code (DTC) indicates the IMRC primary control circuit is low.