Throttle Body: Description and Operation

Throttle Body Assembly:

The throttle body assembly is mounted on the intake manifold and houses the throttle plate, two fuel injectors, fuel pressure regulator, Throttle Position Sensor (TPS), throttle body temperature sensor, Idle Speed Control (ISC) actuator, and a Manifold Absolute Pressure (MAP) sensor.

Intake air flow is controlled by a cable operated throttle plate and by the position of the Idle Speed Control (ISC) actuator (when the throttle lever is at the closed position). Engine idle speed is controlled by the ISC actuator and the ISC actuator is controlled by the engine controller. The throttle lever rests against an adjustment screw at the end of the actuators plunger when the vehicle is idling. The ISC actuator is used to set throttle stop angle during deceleration, and it controls the engine idle speed (throttle lever position) by extending or retracting its plunger.

The throttle body provides metering, atomization, and mixing of the fuel. Once the air and fuel have mixed, the atomized mixture flows into the combustion chamber via the intake manifold.