Electronic Power Control System Function

Electronic Power Control System Function

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

The position of the accelerator pedal is transmitted to the engine control module via two accelerator pedal position sensors (adjustable resistances, accommodated in one housing), that are connected to the accelerator pedal.

The position of the accelerator pedal (driver controlled) is a main input for the engine control module.

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

The throttle valve is operated by the throttle drive according to the instructions of the Engine Control Module (ECM).

With the engine at standstill and the ignition switched on, the Engine Control Module (ECM) activates the throttle valve actuator precisely according to the specifications of the Throttle Position (TP) Sensor. This means, if the accelerator pedal is depressed 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) the engine control module can open and close the throttle valve independently of the accelerator pedal position sensor.

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

After evaluating the torque requirements of the various components (such as the A/C system, automatic transmission, ABS/ESP, etc.), the engine control module calculates the optimal throttle valve opening angle for the current situation.

Aside from that, it results in clearly better pollutant output and consumption values under certain load conditions.

"EPC" is a system containing all components that contribute to determining, controlling and monitoring the throttle valve position, e.g. Throttle Position (TP) Sensor, Throttle Valve Control Module, EPC warning light, Engine Control Module (ECM).