Functions of EPC system

With EPC, the throttle valve is not actuated through a cable from the accelerator. There is no mechanical connection between the accelerator and the throttle valve.

The position of the accelerator pedal is transmitted to the Engine Control Module (ECM) via two accelerator pedal position senders (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 (ECM).

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 approx. half way.

With engine running (under load) the Engine Control Module (ECM) can open and close the throttle valve independently of the accelerator pedal position sender.

That way the throttle valve can already be completely opened, although the accelerator pedal is only depressed half-way. An advantage of this is that throttle losses at the throttle valve are avoided.

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

The Engine Control Module (ECM) calculates after evaluation of torque requirements of the different components (e.g. A/C system, automatic transmission, ABS/ESP, etc.) a throttle valve opening angle optimal for the respective situation.

Observe safety precautions, refer to Safety precautions when working on fuel supply system  .

Observe rules for cleanliness, refer to Rules for cleanliness  .