- Self-diagnosis of the engine management system allows for quick troubleshooting.
- Precise dosing of the amount of injected fuel ensures a reduction in the content of harmful substances in the exhaust gases and low fuel consumption.
- Idle speed and speed limit control is automatic.
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 to 700°C, which is higher than the ignition temperature of diesel fuel. Fuel is injected into the cylinder with some advance and ignites. Thus, spark plugs are not used to ignite the fuel.
Air is drawn into the engine or comes from the turbocharger and passes through the air filter. The turbocharger compresses air, which then enters the intercooler where it is cooled after being heated by compression in the turbocharger. Cooling contributes to a better filling of the cylinders with forced air, which in turn increases the engine torque and power.
To reduce the proportion of harmful substances in the exhaust gases, diesel engines have a diesel oxidation catalytic converter. At the same time, the recirculation system ensures a significant reduction in the content of nitrogen oxides in the exhaust gases. This is achieved by supplying exhaust gases to the engine intake air, which reduces the oxygen concentration in the air entering the engine cylinders. This results in a delayed ignition and a lower combustion temperature, which ultimately reduces the formation of NOx. The exhaust gas recirculation process must, however, be precisely metered, otherwise the soot content in the exhaust gases will increase. To do this, the amount of air drawn in is determined by the meter, which allows the electronic unit to control the recirculation process.
Fuel is injected directly into the combustion chamber.
The bottoms of the pistons are vortex chambers, providing a swirl of the fuel entering the combustion chambers.
The heating of a cold engine is controlled by the engine control unit. When the engine is cold, the injection timing is shifted by the control unit. The engine control unit, in turn, controls the operation of the glow plugs. glow plugs are installed in each cylinder and turn on before starting the engine, work while turning the engine with the starter and for some time after starting the engine. Spark plugs make it much easier to start a cold engine. After the ignition is turned on, the lamp on the dashboard lights up (contact the head Controls and techniques for safe operation), signaling the inclusion of glow plugs. As soon as the lamp goes out, you can start the engine. If the ambient temperature is very low, the spark plugs continue to work for some time after the engine is started. This ensures stable operation of the engine and the reduction of harmful impurities in the exhaust gases.
Due to the good cold start performance of a direct injection engine, preheating is only required at temperatures below -10°C.
Fuel passes through the fuel filter. The filter separates the fuel from water and contaminants. Therefore, it is important to remove water from the fuel and replace the filter element in a timely manner.
2.5L direct injection engine
The location of the elements of the injection system in the compartment of the diesel engine 2.5 l
- 1 - Mass meter with intake air temperature sensor in the upper part of the air filter housing
- 2 - Solenoid valve for limiting boost pressure
- 3 - Terminal 50 connector between starter switch and starter
- 4 - 2-pin connector for the needle stroke sensor. Not available on BCZ engine
- 5 - 3-pin connector of the engine speed sensor.
- 6 - Oil pressure sensor
- 7 - Oil temperature sensor
- 8 - Vacuum drive for adjusting the boost pressure
- 9 - Mechanical exhaust gas recirculation valve
- 10 - Electronics box in the catchment compartment with:
- direct injection system control unit, with height sensor
- AT control unit
- direct injection relay
- glow plug relay
- glow plug fuse
- fuel pump relay
- 11 - Engine speed sensor
Fuel is sucked in by the distribution injection pump from the fuel tank.
High pressure fuel pump creates a pressure of about 900 atm. and injects fuel through multi-jet injectors in two steps, according to the ignition order. First, a small volume of fuel is pre-injected, which creates the necessary conditions for the subsequent injection of the main volume of fuel. This process provides a softer and less noisy combustion of the fuel, similar to how swirl chamber injection occurs.
The injection pump does not require maintenance. All moving parts of the pump are lubricated with diesel fuel. The injection pump is driven from the crankshaft of the engine by a toothed belt.
1.9L direct injection engine
The location of the elements of the injection system in the compartment of the diesel engine 1.9 l
- 1 - Mechanical exhaust gas recirculation valve with intake manifold damper
- 2 - Coolant temperature sensor
- 3 - Connector block pump-injector
- 4 - Fuel temperature sensor
- 5 - Suction pressure sensor with intake air temperature sensor
- 6 — Socket of the gauge of number of turns of the engine
- 7 - Connector for the Hall sensor of the camshaft position
- 8 - Electronics box in the catchment compartment. Direct injection system control unit with height sensor
- 9 - Engine speed sensor
- 10 - Hall sensor of the camshaft position
- 11 — Solenoid valve for limiting boost pressure
- 12 - Vacuum pressure actuator for boost pressure limitation
- 13 — the valve of switching of the gate of the inlet pipeline
- 14 - Valve 1 of the exhaust gas recirculation system
- 15 - Air mass meter
Here the injection takes place through the system «pump nozzle» (illustration below). Unlike the previous injection system, where the fuel is compressed by one injection pump for all injectors, the system «pump nozzle» each cylinder has its own injection pump.
Thus, the injection pump, the control valve and the nozzle are combined in one unit.
Unit injector
- 1 - Nozzle
- 2 - Pressure pump
- 3 - Control unit (solenoid valve)
- 4 - Roller lever
- 5 - Injection cam
- 6 - High pressure cavity
- 7 - Piston spring
- 8 - Pump piston
- 9 - Fuel return
- 10 - Fuel supply
- 11 - glow plug
- 12 - Nozzle needle
Diesel fuel is supplied by an electric fuel pump located in the tank, as well as a mechanical fuel pump that supplies fuel to the pump-injector unit. The mechanical fuel pump, together with the vacuum pump, is mounted on the cylinder head and is driven directly from the camshaft. The four fuel pumps of the unit injector are driven by an additional cam located on the camshaft through a roller lever. The volume of injected fuel is controlled by the engine control unit via solenoid valves.
Due to the high compression pressure in the pump-injector unit, the fuel is very hot, which adversely affects the operation of the fuel reserve sensor in the tank. A special refrigerator is located in the return pipeline to cool the fuel.
Before fuel enters the fuel pump, it passes through the fuel filter. There, water and contaminants are separated from the fuel. Pay attention to the importance of fuel filter maintenance.
Caution: When working on the fuel system, safety precautions and special cleanliness must be observed, refer to Section General information and security measures.
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