The primary function of the engine throttle is to regulate the air/fuel mix. This is achieved by increasing or decreasing the volume of incoming air by means of a butterfly valve in the throttle body. In general, there are three main types of throttle system:

• Mechanical throttle valves controlled via physical linkage from the accelerator pedal
• Electromotive throttle valves controlled through a combination of the accelerator pedal and an ECM
• Electronic throttle valves controlled via an electronic signal from an ECU