Beetle L4-2.0L (AEG) (2000)
Accelerator Pedal Position Sensor: Testing and Inspection
Electronic Power Control (EPC) System, Checking
(Engine Code: AVH, AZG)
Electronic Power Control EPC) system, function
In the EPC or "E-Gas" system, the throttle valve is not operated via 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 the engine control module via two sensors for accelerator pedal position (changeable
resistances; stored in one housing) that are connected with the accelerator pedal.
The position of the accelerator pedal (driver's intention) is a main input value for the Engine Control Module (ECM).
Operation of the throttle valve occurs throughout the entire RPM and load range via an electric motor (throttle valve actuator) in the throttle valve
The throttle valve is operated by the throttle valve actuator according to the specifications 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 exactly according to
the specifications of the accelerator pedal position sensor. This means, if the pedal is depressed half way, the throttle valve actuator opens the throttle
valve to the same degree; the throttle valve is then opened half way.
With the engine running (under load), the Engine Control Module can open and close the throttle valve independently of the accelerator pedal position
In this way, the throttle valve can already be completely open, even though the accelerator pedal has only been depressed half way. This is
advantageous since charging losses at the throttle valve can be avoided.Furthermore, it results in significantly better emissions and consumption values
under certain load conditions.
It would be wrong to assume that "E-Gas" consists of only one or two components. E-Gas is much more of a system containing all components that
contribute to determining, regulating and monitoring the throttle valve position (e.g. accelerator pedal position sensor, throttle valve control module,
Electronic Power Control (EPC) warning lamp, Engine Control Module (ECM))