Throttle Body: Description and Operation

Throttle Body Cross-Section:

The throttle body consists of the main bore, air bypass passage, fuel passage, vacuum passage (for EGR system, vacuum advance, pressure sensor and canister purge system) and the following parts.

^ Injector which injects fuel according to the signal from ECM

^ Fuel pressure regulator which maintains the fuel pressure to the injector a certain amount higher than the pressure in the intake manifold

^ Throttle valve which is interlocked with the accelerator pedal and controls the amount of the air fuel mixture drawn into the combustion chamber

^ TPS which detects the throttle valve opening and sends a signal to ECM

^ Air valve which supplies the bypass air when the engine is cold

^ Idle speed adjusting screw which controls the amount of bypass air to adjust engine idle speed