Ignition system
The ignition system ignites the air-fuel mixture supplied to the combustion chambers of gasoline engines. To form a spark of the required intensity, the 12-volt voltage of the on-board network is converted into high-voltage voltage in the ignition coils installed above each spark plug (high voltage wires are not used).
The electronic ignition system is an integral part of the engine management system. Its main working components are spark plugs and coils. The high voltage supply to the spark plugs is controlled by the electronic engine control module (ECM). Manual adjustment of the ignition timing is not performed - if the required settings are violated, the failed components should be replaced. The components of the ignition system are not subject to wear and do not require regular maintenance. Spark plugs should only be replaced according to the maintenance schedule (see Section 14 Chapter 1).
Preheat system
When a diesel engine is running, clean air is sucked into its cylinders, which is compressed to high pressure. In this case, the air temperature rises above the ignition temperature of diesel fuel. Fuel is injected into the cylinder with some advance and ignites spontaneously. Thus, spark plugs are not used to ignite the fuel in a diesel engine. On a cold engine, the temperature of the compressed air may not reach the required value for ignition. In this case, additional preheating is required.
For this purpose, a glow plug is installed in each cylinder, which heats the combustion chamber. The glow plugs are controlled by the ECM based on signals from the ECT and TFR sensors.
Engine management system, data buses
Basic information on the operation and sensors of engine management and fuel injection systems is set out in Chapter 4.
The control units are connected to each other via CAN and LIN data buses. Thanks to networking, it becomes possible to exchange data between individual control units in a way that is not usual (discrete) cable connections, and through data buses in digital form in the form of an electrical signal. As a result, data is transferred to a larger number of control units.
The CAN bus is divided into five separate main subsystems: CAN-P (drive unit), CAN-C (comfort), CAN-I (Information Systems), CAN-D (diagnostics) and CAN instrument cluster. These subsystems are connected to each other via a diagnostic interface "J533" (see illustration 1.1). To ensure reliable data transmission, the CAN bus wires are twisted cables. An additional single-wire LIN bus with a data transfer rate of 19.2 kbps is connected to the main data buses.
1.1 Structure of data buses (the decoding of the designations of electrical components is given at the end of the Manual, before the wiring diagrams)
Safety measures when working with ignition and fuel injection control systems
To prevent injury and/or failure of electrical and electronic components, the following must be observed:
- do not touch the wiring of the ignition system and do not disconnect its connectors while the engine is running / the starter is rotating;
- disconnect/connect the injection control system fuel lines, ignition system wiring, and any diagnostic and measuring equipment only with the ignition off;
- It is not allowed to carry out maintenance work on the electronic ignition system by people with an implanted pacemaker.