Variable Induction Air Control System: Description

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Infiniti QX4, 2003 Infiniti Q45, 2003 Infiniti M45, 2003 Infiniti I35, and 2003 Infiniti G35. However, it is still accessible from the selected car via links, so may be relevant.

When the engine is running at low or medium speed, the power valve is fully closed. Under this condition, the effective suction port length is equivalent to the total length of the intake manifold collector's suction port including the intake valve. This long suction port provides increased air intake which results in improved suction efficiency and higher torque generation. The system includes a surge tank and one-way valve.

When engine is running at high speed, the Engine Control Module (ECM) sends the signal to the Variable Induction Air Control System (VIAS) control solenoid valve. This signal introduces the intake manifold vacuum into the power valve actuator and therefore opens the power valve to 2 suction passages together in the collector. Under this condition, the effective port length is equivalent to the length of the suction port provided independently for each cylinder. This shortened port length results in enhanced engine output with reduced suction resistance under high speeds.

The power valve is installed in intake manifold collector and is used to control the suction passage of the variable induction air control system. It is set in the fully closed or fully opened position by the power valve actuator operated by the vacuum stored in the surge tank. The vacuum in the surge tank is controlled by the VIAS control solenoid valve.

The VIAS control solenoid valve cuts the intake manifold vacuum signal for power valve control. It responds to ON/OFF signals from the ECM. When the solenoid is off, the vacuum signal from the intake manifold is cut. When the ECM sends an ON signal, the coil pulls the plunger downward and feeds the vacuum signal to the power valve actuator.