This provides the following benefits:
- A) self-diagnosis of the engine, which allows you to quickly detect a malfunction. The system registers the malfunctions that appear, and in case of unsatisfactory engine operation, it is recommended to contact the workshop, where, using a special tester, the registered trouble codes will be read. These faults can then be rectified in a targeted manner;
- b) accurate dosing of injected fuel. This provides a reduction in the content of harmful substances in the exhaust gas and reduces fuel consumption, while maintaining good dynamic qualities of the car;
- V) there is no need to adjust the idle speed, as well as the set speed at which the regulator begins to limit the fuel supply.
All parts of the engine management system are designed for a long service life and practically do not require repair.
As part of the maintenance, it is only necessary to change the air filter element and the fuel filter.
Adjustments and repairs that affect the operation of a diesel engine can only be carried out with the help of expensive instrumentation and therefore should be entrusted to workshops that have the appropriate equipment.
Working principle of diesel engine
In diesel engines, clean air enters the cylinders and is highly 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 is almost at top dead center, diesel fuel is injected into the air, compressed and heated to about +600°C. The fuel is self-igniting, so spark plugs are not needed.
When the engine is cold, compression alone does not reach the ignition temperature of the fuel.
In this case, the engine must be preheated. To do this, each combustion chamber has a glow plug that heats up the combustion chamber. The warm-up time depends on the ambient temperature and is controlled by the engine control unit via the preheat relay.
Attention! Due to the good ability to start a cold engine with direct fuel injection, its preheating is only necessary at air temperatures below 0°C.
The engines fitted to the Golf/Touran have direct injection through the block «pump nozzle».
Unlike conventional direct injection, when one high-pressure fuel pump creates pressure to open all injectors, in diesel engines using this scheme, each cylinder has its own injection pump. This injection pump, control valve and nozzle form a single unit, designated «pump nozzle» (see illustration 1.0).
1.0. Block «pump nozzle»
1 - fuel injector
2 - high pressure pump
3 - solenoid valve
4 - roller rocker
5 - intake camshaft cam
6 - high pressure chamber
7 - spring
8 - pump piston
9 - fuel return channel
10 - fuel supply channel
11 - glow plug
12 - nozzle needle
Diesel fuel is taken from the tank by an electric pump and supplied by a mechanical fuel supply pump to each pump-injector.
The fuel pump, together with the vacuum pump, is mounted on the cylinder head and is driven by the camshaft. All four injection pumps in the block «pump nozzle» are driven by additional cams on the camshaft through roller rocker arms. Due to the high fuel injection pressure of almost 2000 bar, the fuel is strongly atomized at the moment of injection. The amount of injected fuel is precisely determined by the engine control unit and fed through the electromagnetic control valves to the unit «pump nozzle».
Due to the high pressure in the block «pump nozzle» the fuel becomes very hot, which adversely affects the functioning of the fuel gauge sensor.
To cool the fuel on the return fuel line there is a radiator mounted on the bottom of the car.
Before getting into the injection pump or block «pump nozzle», the fuel passes through the fuel filter, where contaminants and condensate are retained. Therefore, it is extremely important to replace the fuel filter at the time required by the maintenance conditions.
Attention! Work on the fuel system requires compliance with safety measures and the strictest cleanliness.
Visitor comments