Ignition

Ignition

The N14 engine has 4 individual ignition coils. The ignition coils generate the ignition high voltage from the on-board supply voltage to ignite the mixture in the combustion chambers. The firing order is 1 - 3 - 4 - 2.
The engine is installed laterally.

Brief description of components

The following components for the ignition are described:

Ignition coils

The ignition coils are activated by the DME control unit. The ignition coils receive terminal 30 from the overload-protection relay of the ignition. Each ignition coil is seated on a spark plug.

System functions

The following system functions are described:

Ignition circuit monitoring

The firing circuit is monitored on the basis of the current in the primary coil of the ignition coil. The current must be within certain values during certain time thresholds for switching on. The following are monitored in the ignition diagnosis:

• Primary power circuit of the ignition coil
  
• Wiring harness for the ignition
  
• Secondary power circuit of the ignition coil with spark plug
  
• Duration of spark combustion
  

The following faults can be detected by the ignition-circuit monitoring:

• Short circuit on the primary side of the ignition coil
  
• Short circuit on the secondary side of the ignition coil
  
• Spark plug
  
• Break in wiring of the activation
  
• Defective ignition output stages
  

The following cannot be detected:

• Sporadic faults, such as loose contacts or activation line
  
• Flashovers in the high-tension circuit parallel to the spark gap without the formation of a coil short circuit
  
  

Notes for Service department

General information

Note! Multiple ignition only in the range close to idling.

The multiple ignition only takes place in the warm-up phase (maximum of 64 °C) as well as in the range close to idling.

No liability can be accepted for printing or other errors. Subject to changes of a technical nature