Electronic Engine Power Control

Electronic Engine Power Control

With an EPC system, the throttle valve is not operated by a cable from the accelerator pedal. There is no mechanical connection between the accelerator pedal and the throttle valve.

The position of the accelerator pedal is communicated to engine control module (ECM) by the throttle position sensor / accelerator pedal position sensor 2 (variable resistances; stored in one housing) that are mounted on the accelerator pedal assembly.

The accelerator pedal position (driver's intention) is a main input unit for the ECM.

Operation of the throttle valve occurs via an electric motor, the throttle drive for in the throttle valve control module. This is true across the entire engine speed and engine load spectrum.

The throttle valve is operated by the EPC according to commands from the engine control module (ECM).

With engine off and ignition switched on, the ECM controls the throttle drive according to input from the throttle position sensor / accelerator pedal position sensor 2. This means, engine load, speed or other sensor inputs are not a contributing factor. If the accelerator pedal is pressed half way, the throttle drive opens the throttle valve to the same degree; i.e. throttle valve is then opened approximately half way.

With engine running under load, ECM can open or close the throttle valve independently of the throttle position sensor / accelerator pedal position sensor 2 based on other sensors or contributing factors.

This means, for example, that under certain conditions the throttle valve could be opened above half throttle even though the accelerator pedal has only been pressed half way. This has the advantage of preventing torque losses from the throttle valve position while under load.

In addition, it can result in a significant reduction in emissions and fuel consumption under lighter engine load conditions.

EPC is an acronym for the system containing all components that contribute to recognizing, actuating and monitoring the position of the throttle valve.