Variable Induction System: Description and Operation

High Speed Inlet Air System:

A unique High Speed Inlet Air (HSIA) performance control system is used only as a means of improving the engine performance above 5000 RPM. It employs a dual port intake manifold in which the high-speed ports are opened by shutter valves and a shutter valve actuator, controlled by the HSIA solenoid, the vacuum reservoir, and the Powertrain Control Module (PCM). Below 5000 RPM, the HSIA solenoid is energized, its air vent is closed, and the vacuum, which keeps the shutter valve closed, is maintained by the vacuum reservoir and the one-way check valve. Above 5000 RPM, the solenoid is deenergized by the PCM, and the vacuum holding the shutters closed is vented, allowing the spring-loaded actuator to pull the shutter valves open. A vacuum reservoir is used to store needed vacuum which otherwise would not be available during wide open throttle and other low vacuum engine operating modes.

High Speed Inlet Air System:

The shutter valve, located in the intake manifold, opens and closes an intake path in the intake manifold which increases the length of the intake runner when opened and shortens the runner when closed. This action improves torque characteristics at low and high engine rpm.