| With the EPC system, the throttle valve is not operated by a cable from the accelerator There is no mechanical connection between the accelerator and the throttle valve. |
| The position of the accelerator is transmitted to the engine control unit by two accelerator position senders (variable resistors together in one housing) connected to the accelerator. |
| The position of the accelerator (driver's requirement) is a main input value for the engine control unit. |
| The throttle valve is actuated by a servomotor (throttle valve positioner) in the throttle valve module over the full range of engine speeds and load conditions. |
| The throttle valve is operated by the throttle valve positioner which is controlled by the engine control unit. |
| When the engine is not running and the ignition is switched on, the engine control unit moves the throttle valve exactly as prescribed by the accelerator position sender. That is, when the accelerator is depressed halfway, the throttle valve positioner opens the throttle valve by the same amount. The throttle is then approximately half open. |
| When the engine is running (under load), the engine control unit can open or close the throttle valve independently of the accelerator position sender. |
| This means that the throttle valve can already be completely open even though the accelerator is depressed half way. This has the advantage of preventing throttling losses at the throttle valve. |
| This also results in significantly improved consumption and exhaust emission values under certain load conditions. |
| After evaluating the torque requirements of various components (e.g. air conditioning system, automatic gearbox, ABS/ESP and so on), the engine control unit calculates the optimal throttle valve opening angle for the respective situation. |
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