Throttle Body: Description and Operation

Throttle Body Injection Unit:

Throttle Body Assembly (Typical):

The throttle body assembly is attached to the intake manifold, and is used to control air flow into the engine, controlling engine output. The throttle valve within the throttle body is opened by the driver through the accelerator controls. During engine idle, the throttle valve is closed, and air flow is handled by the Idle Air Control (IAC) Valve.

The throttle body also provides the location for mounting the Throttle Position Sensor (TPS). Vacuum ports are located above or below the throttle valve to generate vacuum signals needed by various components.