2.3L engine (index 601)
The priming pump pumps diesel fuel from the tank and delivers it through the fuel filter under low pressure to the injection pump. From it, fuel is supplied to the injectors through high-pressure fuel lines. Distinguish between direct and split injection (using prechambers). The engines of these models use a prechamber injection system. It differs in that fuel is injected into a prechamber located in the cylinder head and connected to the main combustion chamber. In the prechamber, the fuel is ignited and the process of its combustion begins. As a result of the resulting pressure, the burning fuel enters the main chamber, where the combustion process is completed.
HPFP is a piston type pump. It is located on the left side of the cylinder block and is driven by the camshaft drive chain. For each engine cylinder in the injection pump there is a separate section consisting of a plunger and a cylinder. The plunger of this section is controlled by the corresponding cam. The plunger is carefully lapped to the cylinder, so it ensures tightness at high pressure. The injection pump lubrication system is connected to the engine lubrication system. A sealing ring is installed on the connection of the injection pump flange with the cylinder block.
The volume of fuel supply is regulated by a spiral groove on the plunger. Depending on the angle of rotation of the plunger, more or less fuel is supplied. The fuel pressure formed under the action of the injection pump plunger raises the nozzle needle and opens the injection hole. Atomized fuel is injected through the nozzle into the prechamber. At the moment when the spiral groove of the plunger opens the return pipe channel, the pressure drops and the nozzle needle falls under the action of the spring.
On the reverse side of the injection pump is the pump control mechanism, which is a system of levers and springs, and a centrifugal regulator at the rear end of the pump camshaft. Diaphragm mechanism for stopping the engine, diaphragm mechanism for increasing the number of idle speeds (if it is installed) and the stop lever respectively affect the operation of the regulator. The regulator controls the position of the injection pump rail, thus regulating the fuel supply. To supply fuel from the tank to the injection pump, a booster piston pump with a mechanical drive is used. The booster pump does not have manual pumping, as was the case with diesel engines of previous releases.
2.9L engine (index 602)
The engine is equipped with an electronically controlled direct injection system, the two most important elements of which are the distribution injection pump and the electronic control unit.
The control unit regulates the fuel supply depending on the position of the fuel supply control pedal, as well as the technical condition of the engine.
The fuel supply and the start of injection are regulated by the pump depending on the following factors:
- positions of a pedal of management of giving of fuel;
- loads (technical condition) engine;
- atmospheric pressure;
- intake air temperature;
- control unit settings.
The engine shutdown occurs as a result of the fuel pump cutting off.
An exhaust gas recirculation system and a catalytic converter can be installed as standard, but vehicles are also sold without these devices. In turn, the operation of the injection system control unit on the 2.9 liter engine does not affect the operation of other devices. The operation of the glow plugs is controlled by a separate control device to facilitate starting. The control unit is equipped with a memory device for recording fault codes that occur, information about which is stored in it even when the ignition is turned off and the battery is removed.
In the event of serious faults, the warning lamp in the instrument cluster comes on. Malfunctions can occur as a result of a malfunction:
- crankshaft position sensor;
- injection pump;
- pump distributor position sensor;
- fuel supply valve;
- check valve;
- regulator valve.
Fuel tank and fuel lines
The fuel tank is located under the floor of the car. Its capacity depends on the modification and is indicated in the user manual. The fuel lines are designed for high pressure, therefore they are made of durable material and connected with clamping and screw clamps. There are direct and return pipelines for returning excess fuel to the tank. Fuel is supplied to the injection pump by a booster pump. A fuel level sensor is installed on the top side of the fuel tank.
A special fuel tank ventilation system is also provided. A vent hose is attached to the filler neck leading to the top of the tank. Air escapes through it when fuel is poured into the tank. Air flows through it and back, with fuel consumption during engine operation, so that a vacuum does not form.
Fuel saving methods
Accelerate smoothly, upshift as soon as possible. When the desired speed is reached, select the optimal gear and allow the vehicle to move with the least amount of pressure on the accelerator pedal. Maximum speed is only allowed when overtaking or driving in heavy traffic. In addition, turn off the engine when stopping at a barrier, traffic light, or at «traffic jam» - even with a 5-7-second pause, fuel is saved.
Diesel fuel
Diesel fuel is specially designed for diesel engines. Due to the high flammability, the self-ignition process occurs in a matter of fractions of a second. The ability of a fuel to self-ignite is characterized by a cetane number, a relative indicator derived in the course of laboratory studies. The substance cetane with a very high flammability is assigned an index of 100, on the contrary, the most slightly flammable methylnaphthalene is an index of 0. The cetane number indicates the content (in percentages) cetane in a certain volume of a given fuel. For diesel fuel, it should be 45.
Diesel fuel mainly consists of so-called paraffins. These hydrocarbons are highly flammable, but at low temperatures they begin to crystallize. Separate crystals quickly connect with each other and form complex compounds. With further cooling, many crystallized chains are formed that do not pass through the fuel filter. Manufacturers solve this problem by adding special additives. Chemical additives prevent the formation of paraffin chains, preventing individual crystals from combining with each other. Individual crystals are small enough to pass through the pores of the filter. As a result, the fuel reaches the injection pump. General recommendations for refueling the car with the appropriate types of diesel fuel:
- refuel diesel fuel corresponding to the season, with a cetane number of at least 45 (according to DIN 51 601);
- additives are not needed for summer diesel fuel. It begins to crystallize at temperatures below -2°C;
- winter diesel fuel with the addition of additives is used at temperatures up to -22°С (DIN standard -12°С).
Summer diesel fuel in winter
If the car has not been driven for 6 months or more, you may need to drive on summer diesel fuel in sub-zero temperatures. In this case, it is necessary to use additives that dilute the fuel, which are sold at gas stations or in auto shops. Consult your dealer for the correct type of additive and carefully read the instructions for use. When pouring the additive, the fuel must be at room temperature. If the fuel in the tank has already thickened, adding an additive will not help. In this case, you need to tow the car to a warm box, where the crystallized paraffins will dissolve again, then you can fill in the additive.
Fuel Handling Precautions
Fuel is flammable. Therefore, during repair work, be careful when working with the engine power system. Special care must be taken when draining fuel. When handling fuel, the following precautions must always be observed:
- remove the terminals from the battery and isolate them;
- Do not drain fuel indoors. To do this, you need to use a special pump. In no case should you do this through the hole of the fuel level sensor or by sucking it with your mouth through one of the hoses - this is dangerous due to possible poisoning by toxic fuel components;
- a Class B fire extinguisher must be available;
- do not drain fuel over the inspection ditch. Fuel vapor is heavier than air, so it will take a long time to erode from the pit. Dangerous consequences in this case are harm to health by inhalation, as well as high explosiveness;
- when working with fuel, make sure that there are no switched on electrical appliances, sources of open flame and sparking in the room;
- for fuel it is necessary to use only specially designed containers that are tightly closed, protected from fire and have a stopper with a pressure equalizer;
- fuel vapors remain in an empty tank, which are also very dangerous. Therefore, all further work must be carried out very carefully.
Fuel drain
The fuel tank does not have a drain hole. Since the direct and return fuel lines are located on the top side of the tank, draining the fuel is not an easy procedure. Fuel draining is carried out as follows:
- insert the hose as deep as possible into the filled tank through the filler neck;
- pinch the hose hole tightly with your finger. The drain container must be below the level of the bottom of the tank. To start draining, pull out the hose slightly and direct it into a container. If the hose is long enough and well immersed in the fuel, it should begin to drain. Sucking fuel by mouth is dangerous to health.
If there is little fuel left in the tank, this method may not be effective. In this case, a special pump must be used for pumping.
Diesel Exhaust Gas Treatment
A catalytic converter is installed in the diesel engine exhaust system. It reduces hydrocarbon and carbon monoxide emissions by up to 50%. The catalytic converter does not filter particulate matter, but it plays a significant role in reducing their proportion in the exhaust gases. Gaseous hydrocarbons usually settle on solid particles, thereby increasing the volume of emitted particles. But, since hydrocarbons are oxidized in the converter, they can no longer settle on solid particles.
Exhaust gas recirculation system
Exhaust gas recirculation system, referred to as AGR (English abbreviation - EGR), serves to reduce the content of nitrogen oxides in the exhaust gases. Part of the gases are removed through a valve-controlled system and re-supplied to the intake manifold, lowering the temperature in the combustion chamber, which leads to a decrease in the content of nitrogen oxides. The operation and management of the recirculation system is controlled by an electronic injection self-diagnosis system (on 2.9 l engine).
This manual does not cover the operation of the system in detail.