Step Motor IAC System

This system uses a step-motor type IACV to control bypass airflow. The IACV consists of a stepmotor with four coils, magnetic rotor, valve and seat, and can vary bypass airflow by positioning it's valve into one of 125 possible "steps". Basically, the higher the IACV step number, the larger the airflow opening and the greater the volume of air bypassed around the closed throttle.

The ECM controls IACV positioning by sequentially energizing its four motor coils. For each coil that is pulsed, the IACVs magnetic rotor moves one step, which in turn changes the valve and seat positioning slightly. The ECM commands larger IACV position changes by repeating the sequential pulses to each of the four coils, until the desired position is reached. If the IaCv is disconnected or inoperative, it will remain fixed at it's last position.

Duty-Control Rotary Solenoid IAC System

This system uses a rotary solenoid IACV to perform idle speed stabilization. Bypass air control is accomplished by means of a movable rotary valve which blocks or exposes a bypass port based on command signals from the ECM. The IACV consists of two electrical coils, permanent magnet, valve, bypass port, and bi-metallic coil.

Duty-Control Rotary Solenoid IAC System

This system uses a rotary solenoid IACV to perform idle speed stabilization. Bypass air control is accomplished by means of a movable rotary valve which blocks or exposes a bypass port based on command signals from the ECM. The IACV consists of two electrical coils, permanent magnet, valve, bypass port, and bi-metallic coil.

Idle Valve Signal Toyota Supra

The ECM controls IACV positioning by applying a duty cycled signal to the two electrical coils in the IACV. By changing the duty ratio (on time versus off time), a change in magnetic field causes the valve to rotate. Basically, as duty ratio exceeds 50%, the valve opens the bypass passage and as duty ratio drops below 50%, the valve closes the passage. If the IACV is disconnect or inoperative, the valve will move to a default position and idle rpm will be around 1000 to 1200 rpm at operating temperature.

2001 Highlander Air Bypass Passageway

Duty-Control ACV System

This system regulates air bypass volume by using an ECM duty-cycle controlled Air Control Valve (ACV). The ACV uses an electric solenoid to control a normally closed air valve which blocks passage of air from the air cleaner to the intake manifold. Since the ACV is incapable of flowing high air volume, a separate mechanical air valve is used to perform cold fast-idle on

Duty-Control ACV System

This system regulates air bypass volume by using an ECM duty-cycle controlled Air Control Valve (ACV). The ACV uses an electric solenoid to control a normally closed air valve which blocks passage of air from the air cleaner to the intake manifold. Since the ACV is incapable of flowing high air volume, a separate mechanical air valve is used to perform cold fast-idle on vehicles equipped with this system. With this type system, the ECM varies bypass airflow by changing the duty ratio of the command signal to the ACV. By increasing the duty ratio, the ECM holds the air bypass open longer, causing an increase to idle speed. The ACV does not have any effect on cold fast idle or warm-up fast idle speed, and is only used during starting and warm curb-idle.

Thermal Vacum Valve Echo 2003

On/Off VSV Type IAC System

This type of IAC system uses a normally closed Vacuum Switching Valve (VSV) to control a fixed air bleed into the intake manifold. This on/off type VSV is controlled by signals from the ECM or directly through the tail lamp or rear window defogger circuits.

On/Off VSV Type IAC System

This type of IAC system uses a normally closed Vacuum Switching Valve (VSV) to control a fixed air bleed into the intake manifold. This on/off type VSV is controlled by signals from the ECM or directly through the tail lamp or rear window defogger circuits.

The ECM controls the VSV by supplying current to the solenoid coil when preprogrammed conditions are met. Also, current can be supplied to the solenoid from the tail lamp or rear window defogger circuits by passing through isolation diodes. Engines using this IAC system must also use a mechanical air valve for cold fast-idle.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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Responses

  • Caragh
    How to bleed air control sensor in 91 toyota celica?
    3 years ago
  • michelle
    What controls iac in 1989 land cruiser?
    2 years ago

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