| Function of the electronic engine power output regulation (E-gas) |
| On the electronic throttle system the throttle valve is not operated by a control cable connected to the accelerator pedal. There is no mechanical connection between the accelerator pedal and the throttle valve. |
| The position of the accelerator pedal is signalled by the engine control unit via two accelerator pedal position senders (variable resistors; located in a housing), which are connected to the accelerator pedal. |
| The accelerator pedal position (driver's instruction) is a main input dimension for the engine control unit. |
| The throttle valve is activated by an electric motor (throttle valve positioner) in the throttle valve control unit over the full speed and load range. |
| The throttle valve is activated by the throttle valve positioner according to the instructions of the engine control unit. |
| With the engine stopped and the ignition on, the engine control unit controls the throttle valve positioner accurately according to instructions from the accelerator pedal position sender. This means that if the accelerator pedal is half pressed the throttle valve positioner opens the throttle valve to the same extent; the throttle valve will thus be approximately half open. |
| With the engine running (under load) the engine control unit may open and close the throttle valve independently of the accelerator pedal position sender. |
| Thus, for example, the throttle valve may already be fully open even though the accelerator pedal is only half pressed. This offers the advantage that throttle losses on the throttle valve can be avoided. |
| The engine control unit analyses the torque demands from the various components (e.g. the air conditioning system, the automatic gearbox, ABS/ESP, etc.) and calculates the optimum throttle flap opening angle for each situation. |
| Moreover, under certain load conditions this may result in clearly improved values as concerns exhaust gas emission and fuel consumption. |
| It would be wrong to assume that the „electronic throttle system“ only consists of one or two components. The electronic throttle is a system that includes all the components, which contribute to determining, controlling and monitoring the position of the throttle valve (e.g. the accelerator pedal position sender, the throttle valve control unit, the EPC warning lamp, the engine control unit, etc.). |
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