Variable Induction System: Description and Operation

Induction Control Valve:

Induction Control Valve Operation:

PURPOSE
Changes intake air velocity.

LOCATION
Under the intake manifold.

OPERATION
^ Low engine speed
During low engine rpm a short intake path is desirable. A shorter intake path increases engine response and torque. During high torque demand periods, the control solenoid is not energized. This prevents vacuum from operating the actuator diaphragm. When the induction control valve is closed, intake air flows from the individual throttle bores directly into the corresponding intake chambers, with no crossover effect between cylinder banks. This creates a short air flow path into the combustion chambers.

^ High engine speed
During high engine speed a long intake path is desirable. A long intake path increases engine horsepower. During high engine speeds the ECU energizes the control solenoid, allowing vacuum stored in a tank to act upon the actuator diaphragm. Vacuum moves the diaphragm which in turn opens the induction control valve. When the valve opens, it connects the two halves of the intake collector together. Intake air is allowed to flow from both throttle bores to the cylinder that has the most vacuum (intake stroke). Since some of the air flows from the corresponding throttle bore to the cylinder and part from the opposite one, the intake air path is increased.