Which component of a fuel-injected engine is responsible for controlling air intake?

The throttle body is a critical component of a fuel-injected engine that regulates the amount of air entering the engine's combustion chamber. It does this by using a butterfly valve that opens and closes in response to the driver's accelerator pedal input. When the pedal is pressed, the valve opens wider, allowing more air to flow into the engine. Conversely, when the pedal is released, the valve closes, reducing airflow.

This process ensures that the engine receives the appropriate amount of air to mix with the fuel for combustion, directly influencing engine performance and efficiency. The throttle body's design and operation are essential for maintaining optimal air-fuel ratios, which are crucial for achieving the desired power output and emissions control.

The other components listed, such as the fuel pump, carburetor, and alternator, serve different functions. The fuel pump delivers fuel to the engine, the carburetor is used in some older engines to mix fuel and air (but is not found in fuel-injected engines), and the alternator generates electrical power. Thus, these components do not control air intake in the same manner as the throttle body.