Table of contents: Preheat system ↓ Engine management system, data… ↓
Preheat system
When a diesel engine is running, clean air is sucked into its cylinders and 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 self-ignites. Therefore, spark plugs are not used to ignite the fuel in a diesel engine. On a cold engine, the compressed air temperature may not reach the value required for ignition. In this case, additional preheating is necessary.
For this purpose, a glow plug is installed in each cylinder, which heats the combustion chamber. The operation of the glow plugs is controlled by the ECM based on signals from the ECT and SKR sensors.
Engine management system, data transmission buses
Basic information on the operation and sensors of the engine management and fuel injection systems is presented in Chapter 4.
Most control units are connected to each other via data buses. Thanks to the networking, it becomes possible to exchange data between individual control units in a way that is not conventional (discrete) cable connections, and via data transmission buses in digital form in the form of an electrical signal. Due to this, data transmission is carried out to a larger number of control units.
The CAN bus is divided into five separate main subsystems: CAN-P (drive), CAN-C (comfort), CAN-D (diagnostics), CAN instrument cluster and CAN additional. These subsystems are interconnected via the J533 diagnostic interface. To ensure reliable data transfer, the CAN bus wires are twisted cables.
An additional single-wire LIN bus is connected to the main data buses. The multimedia system units are connected via an optical MOST bus.