Variable Induction System: Description and Operation

GENERAL
- The induction control system opens and closes the induction control valve to change the intake air flow rate according to engine operation, thereby increasing the amount of air introduced in the cylinders.
This increase in the amount of air is generally referred to as the "high" charging efficiency.
- The induction control system consists of the following parts:
- ECM
- Induction control solenoid valve (turns the vacuum applied to the diaphragm ON or OFF).
- Induction control valve (installed in collector chamber)
- Diaphragm (to open/close induction control valve)
- Vacuum tank
- Check valve








- The induction control valve operates on the intake manifold pressure transmitted to the diaphragm. The intake manifold pressure is controlled by opening/closing the induction control solenoid valve which is determined by the ECM according to the engine speed and amount of fuel injection.

FUNCTION
Engine at standstill
- While the engine is off, vacuum pressure is not applied to the diaphragm. The induction control valve is open.

Engine idling
- While the engine is idling, no signal is sent from the ECM. The induction control valve is open.

Engine operating at low speeds
- The induction control valve is open with engine operating under light loads.
- As load increases, the engine picks up speed and then operates in the intermediate speed range. At this point, the induction control valve closes, allowing the left and right collector chamber intake air passages to operate independently of each other.

Engine operating at intermediate speeds (2,300 - 4,200 rpm)
- The induction control system receives a signal from the ECM. At this point, the induction control solenoid valve turns on (opens). Intake manifold vacuum~pressure will then act on the diaphragm, closing the induction control valve. Now, even when the intake manifold vacuum pressure is decreased with changes in engine conditions, the check valve is closed, constantly maintaining vacuum pressure inside the vacuum tank. The induction control valve is also closed.

Engine operating at high speeds
- The induction control valve receives a signal from the ECM, turning off (closing) the induction control solenoid valve. At this point, atmospheric pressure from the solenoid valve end acts on the diaphragm, moving the induction control valve back. The induction control valve will then open, connecting the left and right collector chamber air passages.