Checking electronic power control (EPC) — VW

VW
Polo
2002
Engine
4 cyl. injection engine, (2 valves, roller rocker fingers)
Edition
10.2004
Checking electronic power control (EPC)
Support
Connector
Black, 6-pin
Accelerator pedal position sender
G79
and
Accelerator pedal position sender -2-
G185
To remove it the instrument panel and the pedal cluster cover must be removed
10 Nm
Function of EPC system
With the EPC system the throttle valve is not operated by a cable. There is no mechanical connection between accelerator and throttle valve.
The position of the accelerator is transmitted to the engine control unit by two accelerator position senders (variable resistors together in a housing) which are connected to the accelerator pedal.
The position of the accelerator (driver's requirement) is the main input value for the engine control unit.
The throttle valve is operated over the complete revolution and load range by an electric motor (throttle valve positioner) in the throttle valve control part.
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 pedal position sender. This means that 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 pedal position sender.
This means that the throttle valve can already be completely open even though the accelerator pedal is only depressed half way. This avoids choking losses caused by the throttle valve.
This also gives vastly improved consumption and exhaust emission levels at certain load conditions.
After evaluating the torque requirements of various components (e.g. air conditioning, automatic gearbox, ABS/ESP and so on), the engine control unit calculates the optimal throttle valve opening angle for the respective situation.
The EPC is a system, which is comprised of different components which have an influence, control or monitor 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.
Observe safety precautions
Chapter
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Observe rules for cleanliness
Chapter
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