The 2.1-liter XUD11BTE/L3 engine is equipped with the EPIC fuel injection system developed by Lucas. The injection pump of this engine has fuel supply control valves, an electromagnetic valve for adjusting the fuel injection timing, a fuel cut-off valve and various sensors, including a fuel temperature sensor, a position sensor of the distributor rotor and cams.
The letter L in the engine designation means that this engine does not have a catalytic converter, Y means that it is equipped with a catalytic converter, and L3 indicates the level of harmful substances in the exhaust gases and compliance with EU standards.
Cars with DK5ATE engine have Bosch MSA 11 3 6 VP36 fuel system.
In diesel engines, air is admitted into the combustion chambers of the cylinders and is strongly compressed there. Because of this, the temperature in the cylinders becomes higher than the ignition temperature of diesel fuel. At the moment when the piston of the cylinder is almost at the top dead center, diesel fuel is injected into the air, compressed and heated to +600-700°C. The fuel ignites spontaneously, so spark plugs are not needed.
When the engine is very cold, the ignition temperature is not reached by compression alone. In this case, the engine must be preheated. For this purpose, each combustion chamber has a glow plug, which preheats the chamber. The duration of the preheating depends on the ambient temperature and is regulated by the engine control unit via the preheating relay.
Preheating and maintenance work the same on all engines. The regulator that controls the operation of the preheating and maintenance unit acts as a relay, from which power is supplied to the preheating plugs. Power is supplied to the preheating plugs, as well as to the control lamp of this device, when the ignition is turned on, if the coolant temperature is below 60°C. After some time, the regulator disconnects the voltage supply to the preheating plugs. At the same time, during the engine start-up phase, power is supplied to the plugs and their heating continues for some time after start-up.
Preheating support means that the glow plugs continue to glow after the engine has started. Support begins immediately after the engine has started and the starter has been disconnected. During the first 15 seconds, the voltage supply to the glow plugs cannot be interrupted. After 15 seconds, the voltage supply may be disconnected if the coolant temperature is above 60°C or if the accelerator pedal is in a certain position or is pressed beyond the programmed time.
To reduce the content of harmful substances in the exhaust gases, a so-called unregulated catalyst is installed on modified engine models. A further reduction in the amount of nitrogen compounds in the exhaust gases is ensured by the exhaust gas recirculation system by diverting a portion of the exhaust gases for re-burning and mixing it with the taken-in atmospheric air. The volume of exhaust gases returned for re-burning must be dosed, because their uncontrolled flow leads to the formation of carbon deposits and an increase in the content of solid particles in the exhaust gases. All engines are equipped with an exhaust gas recirculation system, regardless of whether a catalyst is installed or not. The exhaust gas recirculation system reduces the emission of harmful substances into the atmosphere by directing a portion of the exhaust gases to the intake manifold. Exhaust gas recirculation occurs only under certain conditions, depending on the coolant temperature and the engine load. A corresponding signal about the coolant temperature comes from the coolant temperature sensor in the exhaust pipe. EGR occurs when the engine temperature exceeds 60°C, and the engine load does not exceed the nominal load value set in the load sensor attached to the injection pump. The control unit opens the electromagnetic EGR valve, which regulates the operation of the entire EGR system. In this case, the vacuum pressure generated by the vacuum pump located on the camshaft opens the mechanical EGR valve installed on the exhaust manifold, and part of the EGR is diverted to the intake manifold.
When the engine is running at low speeds, the low pressure generated by the vacuum pump reaches its maximum. The mechanical exhaust gas bleed valve then remains open, diverting the exhaust gas into the intake manifold. The exhaust gas circulation is maintained by the pressure difference between the intake and exhaust manifolds, determined by the throttle valve, which closes almost completely.
As the engine accelerates and revs up, the low pressure generated by the vacuum pump drops and the mechanical EGR valve is gradually closed by a spring, reducing the amount of EGR directed into the intake manifold. At the same time, the throttle valve opens, allowing more fresh air in.
The diesel engine control unit recognizes faults and malfunctions in the fuel system and records them, creating an error log, where faults are recorded as codes. In the workshop, using a tester connected to the diagnostic connector, the log can be printed or read in order to specifically eliminate the registered faults, without wasting time and effort searching for them.
Before getting into the high-pressure fuel pump, the fuel passes through the fuel filter. Contaminants and condensate are retained in the filter, so it is extremely important to change the fuel filter in a timely manner or remove condensate from it. The high-pressure fuel pump does not require maintenance. All rubbing parts of the pump are lubricated with diesel fuel.
The required volume of injected fuel is determined and set by a microprocessor, which regulates the duration of opening of the valve injectors. Electromagnetic fuel injectors are individually controlled by signals from the electronic control unit, and the injectors inject fuel directly into the combustion chambers.
The crankshaft position sensor transmits signals to the engine control unit that allow the correct determination of the fuel injection timing.
The accelerator pedal position sensor potentiometer transmits information about the pedal position to the engine control unit.
To improve passive safety, cars are equipped with a safety sensor (switch), which is triggered in the event of a sudden forced stop of the vehicle, as occurs in a collision, and switches off the fuel pump. The switch can be returned to the working position by pressing its button.
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