Accelerator Pedal

The accelerator pedal is the right most pedal in the driver's foot well and is responsible for regulating the engine throttle control. The position of the pedal represents the 'openess' of the throttle, a fully raised pedal will be a closed throttle position whereas a fully depressed pedal will correspond to a wide open throttle position. The wider the throttle position the more air and fuel flow into the engine, the more air and fuel the more power and acceleration.

On older cars the accelerator pedal would have been connected to a cable that connects the pedal directly to the throttle body. Modern cars use a 'drive by wire' system that essentially transmits the pedal position as a digital signal to the ecu, the ecu then manages the throttle position. This allows for more safety systems to come into play as the ecu has ultimate control over the throttle rather than the driver.

Accelerator pedals can have problems mechanically and also with the sensor. There is added complexity for automatic cars as the pedal will also have a 'kick down' feature that tells the ecu to apply as much throttle as the engine can handle.