A8 Quattro Sedan V8-4.2L (AUX) (2001)
Electronic Throttle Control Module: Description and Operation
Electronic throttle system, function
With the electronic throttle, the throttle valve is not operated by a cable connected to the accelerator pedal. There is no mechanical link between the
accelerator and the throttle valve.
The position of the accelerator pedal is communicated to the engine control module by two accelerator position sensors (variable resistors, both installed
in a single housing) which are connected to the accelerator pedal.
The accelerator position (as determined by the driver) is one of the main input values for the engine control module.
The throttle valve is actuated by a servomotor (throttle valve positioner) in the throttle valve control part over the full range of engine speeds and load
The throttle valve positioner actuates the throttle valve according to the commands it receives from the engine control module.
When the engine is running (i.e. under load) the engine control module can open and close the throttle valve freely (i.e. independently of the signals
being sent by the accelerator position sender).
The electronic throttle is not simply a combination of two or three components, but rather a complete system comprising all the elements that together
determine the position of the throttle valve and also control and monitor it. For example, the accelerator position sensor, throttle valve control module,
EPC warning lamp, engine control module etc