Audi A4, S4

Since 2000 of release

Repair and car operation



Audi A4, S4
+ Introduction
+ Controls and receptions of safe operation
+ Current leaving and service
+ The engine
+ Systems of cooling, heating and the air conditioner
- Power supply systems, release and decrease in toxicity of the fulfilled gases
   + Power supply systems of petrol and diesel engines
   + System of injection of fuel of the petrol engine
   - System of injection of fuel of the diesel engine
      The general information
      Operation in the winter
      Checks of system of injection of fuel
   + Systems of release and decrease in toxicity of the fulfilled gases. turbocharger
+ Systems of an electric equipment of the engine
+ Manual box of a gear change
+ Automatic transmission
+ Coupling, power shafts and differential
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment



System of injection of fuel of the diesel engine

The general information

The fuel system of the diesel engine copes an electronic control system of the engine. It has following advantages:

  • Self-diagnostics of a control system by the engine allows to make fast troubleshooting.
  • Exact dispensing of quantity of injected fuel provides reduction of the maintenance of harmful substances in the fulfilled gases and the low expense of fuel.
  • Regulation of turns of idling and restriction of turns is made automatically.

At work of the diesel engine in its cylinders pure air which is compressed to a high pressure is soaked up. Thus air temperature rises to 700С, exceeding temperature of ignition of diesel fuel. Fuel is injected into the cylinder with some advancing and ignites. Thus, spark plugs for fuel ignition are not used.

Air in the engine is sucked in or arrives from турбокомпрессора and passes through the air filter. turbocharger compresses air which then arrives in интеркулер where it is cooled after heating as a result of compression in турбокомпрессоре. Cooling promotes the best filling of cylinders with forced air that in turn raises a twisting moment and capacity of the engine.

For reduction of a share of harmful substances in the fulfilled gases diesel engines have diesel oxidising каталитический the converter. Simultaneously the system recycling provides essential decrease in the fulfilled gases of the maintenance of oxides of nitrogen. It is reached thanks to giving of the fulfilled gases to air soaked up by the engine that provides decrease in concentration of oxygen in air arriving in cylinders of the engine. It leads to a delay of ignition and to lower temperature of combustion that as a result reduces formation NOx. Process recycling the fulfilled gases should be dosed out precisely however, the soot maintenance otherwise increases in the fulfilled gases. For this purpose the quantity of sucked in air is defined by a measuring instrument that allows the electronic block to operate process recycling.

Fuel injection is carried out directly in the combustion chamber.

In the bottoms of pistons there are the vortical chambers providing a turbulence of combustion arriving in chambers of fuel.

Management of warming up of the cold engine is carried out by the engine management block. At the cold engine the injection moment is displaced by the management block. The engine management block, in turn, operates work of candles накаливания. Candles накаливания are established in each cylinder and join before engine start, work during time проворачивания the engine as a starter and some time after engine start. Candles considerably facilitate start of the cold engine. After ignition inclusion on a control panel the lamp (address to the Head Controls and receptions of safe operation), signalling about inclusion of candles накаливания lights up. As soon as the lamp will go out, you can start the engine. If air temperature very low, candles continue to work still some time after engine start. It reaches stable work of the engine and decrease in harmful impurity in the fulfilled gases.

Owing to high starting qualities of the engine with direct injection in a cold condition preliminary heat is required only at temperature more low-10S.

Fuel passes through the fuel filter. In the filter fuel separates from water and pollution. Therefore it is important to delete water from fuel and to make timely replacement of a filtering element.

The engine of 2.5 l with direct injection

Arrangement of elements of system of injection in a compartment of the diesel engine of 2.5 l

1 — the Measuring instrument of weight with the gauge of temperature of soaked up air in the top part of the case of the air filter
2 — the Electromagnetic valve of restriction of pressure надува
3 — the Socket of the plug 50 between the switch of a starter and a starter
4 — a 2-contact socket of the gauge of a course of a needle. On engine BCZ is absent
5 — a 3-contact socket of the gauge of number of turns of the engine.
6 — the Gauge of pressure of oil
7 — the Gauge of temperature of oil
8 — the Vacuum drive of adjustment of pressure надува
9 — the Mechanical valve recycling the fulfilled gases

10 — electronics Box in a water modular compartment with:
- The block of management of system of direct injection, with the height gauge
- The block of management АТ
- The relay of system of direct injection
- The relay of candles накаливания
- Safety lock of candles накаливания
- The relay of the fuel pump
11 — the Gauge of number of turns of the engine

Fuel is soaked up distributive ТНВД from a fuel tank.

ТНВД creates pressure nearby 900 атм. Also injects fuel through multijet atomizers in two steps, according to ignition order. At first preliminary injection of small volume of fuel that creates necessary conditions for the subsequent injection of the basic volume of fuel is made. Such process provides softer and less noisy combustion of fuel just as it occurs at вихрекамерном injection.

ТНВД does not demand service. All mobile parts of the pump are greased with diesel fuel. Drive ТНВД is carried out from a cranked shaft of the engine by a gear belt.

The engine of 1.9 l with direct injection

Arrangement of elements of system of injection in a compartment of the diesel engine of 1.9 l

1 — the Mechanical valve recycling the fulfilled gases with заслонкой the inlet pipeline
2 — the Gauge of temperature of a cooling liquid
3 — the Socket of the block the pump-atomizer
4 — the Gauge of temperature of fuel
5 — the pressure Gauge всасывания with the gauge of temperature of soaked up air
6 — the Socket of the gauge of number of turns of the engine
7 — the Socket of the gauge of the Hall of position of a camshaft
8 — electronics Box in a water modular compartment. The block of management of system of direct injection with the height gauge

9 — the Gauge of number of turns of the engine
10 — the Gauge of the Hall of position of a camshaft
11 — the Electromagnetic valve of restriction of pressure of pressurisation
12 — the Vacuum drive of pressure of restriction of pressure of pressurisation
13 — the switching Valve заслонки the inlet pipeline
14 — the Valve of 1 system recycling the fulfilled gases
15 — the Measuring instrument of weight of air

Here injection occurs by means of system "pump-atomizer" (an illustration more low). Unlike the previous system of injection where fuel is compressed by one ТНВД for all atomizers, system "pump-atomizer" has for each cylinder own ТНВД.

Thus, ТНВД, the operating valve and an atomizer are united in one block.

The block the pump-atomizer

1 — the Atomizer
2 — the pressure Pump
3 — the management Block (the electromagnetic valve)
4 — the Roller lever
5 — an injection Cam
6 — a high pressure Cavity

7 — a piston Spring
8 — the pump Piston
9 — fuel Return
10 — fuel Giving
11 — the Candle накаливания
12 — an atomizer Needle

Giving of diesel fuel is carried out by the electric fuel pump located in a tank, and also the mechanical fuel pump submitting fuel to the block the pump-atomizer. Mechanical fuel насосвместе with the vacuum pump it is fixed on a head of cylinders and it is set in motion directly from a camshaft. Four fuel pumps of the block the pump-atomizer are set in motion by the additional cam, located on distributive to a shaft, through the roller lever. The volume of injected fuel is regulated by the block of management of the engine through electromagnetic valves.

Owing to a compression high pressure in the block the pump-atomizer fuel strongly heats up that negatively affects work of the gauge of a stock of fuel in a tank. For fuel cooling in the returnable pipeline there is a special refrigerator.

Before fuel hit in the fuel pump it passes through the fuel filter. There from fuel separate water and pollution. It is necessary to pay attention to importance of service of the fuel filter.

At work with fuel system it is necessary to observe security measures and special cleanliness, address to Section the General data and security measures.