Engine Performance - Functional Description: Ignition: Notes

The engine features an inductive ignition system with static ignition distribution.

The ignition circuit consists of the following components:

• Ignition coil with primary and secondary coil
• Ignition output stage in the Digital Motor Electronics (DME) for controlling the current via the primary coil
• Spark plug which is connected to the secondary coil.

Each spark plug is activated by a high voltage from a separate ignition coil (pencil ignition coil) that is inserted directly into the cylinder head cover and activates a separate ignition output stage in the Digital Motor Electronics (DME). The ignition coils use the vehicle voltage to generate this high voltage that ignites the fuel-air mixture in the combustion chambers.

The point at which the ignition spark ignites the fuel-air mixture must be set so as to ensure optimum torque, low fuel consumption and minimum pollutant emissions. The essential variables are:

• Engine speed
• Engine torque
• Air ratio value
• Coolant temperature
• Intake air temperature.

These values are recorded by sensors, processed by the Digital Engine Electronics (DME), digitalized and output as a signal for the ignition output stages.