Ignition System, Basic Function - GF07.10-D-1035A

Engine 274 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 

General 

The ignition system initiates the ignition of the fuel/air mixture in spark-ignition engines through a high-voltage ignition spark. With this, it contributes substantially to the generation of the specific engine output and influences the combustion emissions as well as engine torque and the exhaust gas temperature.

Function requirements 

• Engine management ON (circuit 87M)

Function 

Single spark ignition 

Ignition coils are charged once per ignition process and an ignition spark is generated. Single-spark ignition is characterized by a long charging time for the ignition coils.

Multi-spark ignition 

To ignite the fuel/air mixture optimally, even under critical conditions (e.g. high flow rates), the multi-spark ignition is used.

After the compression of the fuel/air mixture and supercharging by the respective ignition coil, a spark plug generates up to four ignition sparks at distances defined at time intervals for multi-spark ignition. As a result, efficient combustion of the fuel/air mixture is achieved, the fuel consumption is reduced correspondingly and an optimized output of the combustion engine is generated. Between the ignition sparks, the ignition coils do not discharge completely. When the charging current is interrupted at the firing point, an ignition spark is produced. In order to reduce the charging time until the next spark, energy is stored for the next ignition spark through intermediate charging.

Ideal development of the primary and secondary current for a multi-spark ignition 

Courtesy of MERCEDES-BENZ USA