Ignition system (VW Golf 4)

The ignition system creates a spark discharge in each engine cylinder at a certain moment, which ignites the compressed fuel mixture. To create a spark in the ignition coil, the battery voltage of 12 V is converted into a high ignition voltage of 25,000–30,000 V.

To determine the ignition timing, the control unit uses information stored in memory and information from sensors installed on the engine. The ignition system receives control signals from the Hall sensor or pulse sensor. Additionally, the ignition timing is also adjusted based on the signal from the knock sensor, which is sensitive to premature ignition and, accordingly, reduces the ignition timing.

Warning: When working on the ignition system, to avoid damaging semiconductor devices (diodes and transistors), the following requirements must be met:

• do not disconnect the battery, alternator or any electrical connections while the engine is running;
• when performing any work, remove the negative terminal from the battery;
• when performing electric welding work on a vehicle, turn off the generator and control unit;
• do not operate the engine with the generator disconnected from the electrical system.

Warning: Do not touch or disconnect high-voltage wires with your hand while the engine is running or while the engine is cranking with the starter.

Warning: Disconnect ignition system wires and instrument wires only when the ignition is off.

Warning: Wash the engine only with the ignition off.

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