Variable Induction System: Description and Operation

Variable Intake Control System. (VICS)





Low to medium speed torque is boosted with a variable intake manifold controlled by the ECM via a Variable Intake Control System. (VICS). The VICS consists of an actuator (operated by engine vacuum) and a solenoid which is turned ON (open) or OFF (closed) by the ECM (ground controlled) to allow vacuum to operate the VICS actuator. A vacuum chamber with a check valve is fitted to ensure a stable supply of vacuum to the VICS actuator. The system is designed to direct intake airflow through long runners below 3500 � 100 RPM. Above 3500 RPM, the ECM activates the vacuum control solenoid, which in turn allows manifold vacuum to operate the VICS actuator; intake airflow is then redirected through shorter intake runners.






Variable Intake Manifold






Low to medium speed torque is boosted through the use of a Variable Intake Manifold. The PCM controls this function utilizing a Variable Intake Motor. Based on engine RPM, the position of the shutter within the intake manifold is changed, thereby directing intake air through a longer path (for low RPM operation) or a shorter path (for high RPM operation). Two Hall-effect sensors, supplied with a 5-volt reference, detect shutter position and relay this information to the PCM.

The PCM activates the Variable intake motor to change
shutter position at 3750 RPM; shutter position change is completed at 4750 RPM.

The chart below shows the number of steps in the variable intake motor and the
RPM ranges for each step: