Throttle Body
A butterfly valve that controls the amount of air entering the engine's intake manifold in response to accelerator inputs.
The throttle body is a critical component of the air intake system that controls the amount of air entering the engine. Located between the air filter box and the intake manifold, it contains a pivoting flat butterfly valve (throttle plate) that opens and closes in response to accelerator pedal inputs.
In older vehicles, the throttle plate was connected directly to the gas pedal via a steel cable. Modern vehicles use an electronic **drive-by-wire** system, where the gas pedal sends an electronic signal to the engine computer (ECM), which activates an electric motor inside the throttle body to position the plate. The throttle body also houses the **Throttle Position Sensor (TPS)** to monitor plate angle.
Over time, oil vapors and carbon soot can accumulate on the inner walls of the throttle body and around the butterfly valve. This carbon buildup restricts airflow, particularly when the valve is nearly closed at idle, causing a rough idle, engine stalling, hesitation under acceleration, or a sticky gas pedal.
Cleaning the throttle body with a specialized spray cleaner is a common maintenance procedure that restores smooth idle quality. If the internal electric actuator or TPS sensor fails, the entire throttle body must be replaced.