Electronic Power Control (EPC) System, Significance

EPC System, Function

For Electronic Power Control (EPC) system, the throttle valve is not operated by a cable from accelerator pedal. There is no mechanical connection between accelerator pedal and throttle valve.

The position of accelerator pedal is communicated to Engine Control Module (ECM) via two sensors for accelerator pedal position (variable resistances; stored in one housing) that are connected with accelerator pedal.

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

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

The throttle valve is operated by throttle valve actuator according to instructions of the ECM.

With ignition switched on and engine off, the ECM activates throttle valve actuator precisely according to sensor for accelerator pedal position. This means, if accelerator pedal is depressed half way, the throttle valve actuator opens the throttle valve to the same degree; i.e. throttle valve would be opened half way.

With engine running (under load), the ECM can open or close throttle valve independently of sensor for accelerator pedal position.

This means, for example, that the throttle valve could be fully opened even though accelerator pedal has only been depressed half way. This has the advantage of preventing torque losses at throttle valve.

In addition to this, it results in significantly better values relative to emissions and consumption under certain load conditions.

The required engine torque can be achieved by Engine Control Module (ECM) via optimal combination of throttle valve diameter and boost pressure.

It would be incorrect to think that (EPC) consists of only one or two components. The Electronic Power Control (EPC) system is much more of a system, containing all components that contribute to recognizing, controlling and monitoring position of throttle valve, e.g. sensor for accelerator pedal position, throttle valve control module, EPC warning lamp, Engine Control Module (ECM).