Audi A4, S4

Since 2000 of release

Repair and car operation

Power supply systems of petrol and diesel engines

The general data and security measures

Petrol engines

Into structure of fuel system enter: a fuel tank, the fuel pump and fuel pipelines, and also fuel and air filters. Instructions concerning the fuel filter of the diesel engine are resulted in the Head Current leaving and service.

The fuel tank has volume about 70 l and is located before a back suspension bracket of the car. The current volume of fuel in a tank is displayed to the driver on a control panel. The fuel tank has ventilation system. On the petrol engine of pair gasoline gather in an adsorber and move in chambers of combustion of the engine.

The accelerator cable is absent. Instead of it on a pedal the gauge of its position is established.

Essential influence on the fuel expense renders style of driving of the car. Some councils about the reasonable reference with a gas pedal are more low resulted.

• After engine start at once get under way from a place even if it occurs on a frost.
• At a car stop for a while more than on 40 with, switch off the engine.
• Move always on as much as possible high transfer.
• At movement on the big distances whenever possible support uniform speed. Avoid movement on high speeds. Operate the car circumspectly. Without need do not brake.
• Do not transport on the car excessive cargo. If the luggage carrier is not used, remove it from a roof.
• Check pressure of air in tyres. Do not suppose excessive pressure decrease.

Diesel engines

At work of the diesel engine in its cylinders pure air which is compressed to a high pressure is soaked up. Thus air in the cylinder heats up to the temperature exceeding temperature of ignition of diesel fuel. Fuel is injected into cylinders where air temperature makes nearby + 600 °С, with some advancing and ignites itself. Thus, spark plugs for fuel ignition are not required.

There can be a situation when at very cold engine owing to compression the necessary temperature of ignition is not reached. In this case it is necessary to make preliminary heating of the engine. In each cylinder there is a candle накаливания which makes heating of the chamber of combustion. Duration of preheat depends on external temperature and is regulated by the engine management block through the preheat relay.

For the diesel engine is available three various ways of injection of fuel: by means of the vortical chamber, the prechamber and direct injection.

At вихрекамерном and prechamber injection fuel is injected into the preliminary chamber of the corresponding cylinder. The mix ignites at once. The volume of oxygen which is available in the preliminary chamber is sufficient for combustion only parts впрыснутого fuel. The remained not burnt down part of fuel the pressure, arisen in the course of combustion, is thrown out in the combustion chamber. There fuel burns down completely.

At direct injection fuel is injected directly into the combustion chamber.

Fuel moves топливоподкачивающим the pump under the pressure of 3.5 атм. To the fuel pump of a high pressure (ТНВД). In ТНВД already at low numbers of turns constant pressure of compression from above 1300 атм is created.

Into structure of fuel system enter: a fuel tank, the fuel filter, atomizers, fuel tubes and hoses, the gauge of a stock of the fuel, located in a tank and the block of electronic control by the engine.

Fuel moves the special pump through the filter. In the filter the dirt and the water containing in fuel settles.

The engine copes the electronic system similar to a control system by petrol engines. The system operates engine work, analyzing the information arriving from a great number of gauges.

The valve отсечки fuel at ignition deenergizing is absent. To muffle the engine at ignition deenergizing, the engine management block sends a signal which, in turn, stops fuel giving to atomizers to the block of management ТНВД.

The fuel system is designed so that not to admit «подсоса» air in the absence of fuel in a tank. The management block constantly checks fuel level in a tank, processing the information arriving from the gauge of a stock of fuel, located in a tank. At falling of a stock of fuel to certain level the management block lights warning lamp on a control panel then compulsorily causes admissions of giving of fuel, limiting to that the maximum speed. It proceeds until fuel level in a tank will not exceed an admissible mark.

The fuel system of diesel engines is very reliable. At use of pure fuel and performance of regular service it should function regularly before the termination of service life of the car. After very big run internal components of atomizers can wear out, and they will be necessary for repairing. As the pump - atomizers have a difficult design, repair is recommended to be carried out in a specialised workshop.

Security measures and rules of observance of cleanliness at work with fuel system

• Do not use near to a workplace open fire, do not smoke and do not hold any strongly разогретых subjects. There is a danger of accident! Keep in readiness the fire extinguisher.
• Watch normal ventilation of a workplace. Fuel steams are poisonous.
• The fuel system is under pressure. At opening of system fuel can be pulled out under pressure. Collect fuel a rag. Use goggles.
• At work with components of the power supply system of the diesel engine observe special safety measures. In especial degree it concerns atomizers. Keep in mind that pressure of fuel upon an exit makes of atomizers about 1100 atmospheres. Do not suppose hit of any parts of a body under a fuel stream.
• Shlangovye connections fasten by means of tape or tightening collars. It is necessary to replace tightening collars with tape collars or collars of last design necessarily. For installation of tape collars there is a special adaptation, for example HAZET 796-5.
• Connections and places adjoining to them before opening carefully clear.
• The removed details stack on a pure lining and close. Apply for this purpose polyethylene or a paper. Do not apply for this purpose a fibrous fabric!
• Carefully close open details or put technological заглушки if repair lasts some time.
• Establish into place only pure details. Spare parts take out from packing only directly ahead of installation. Do not apply details which were stored unpacked (for example, stored in a tool box).
• At the opened fuel system whenever possible do not work with compressed air. Whenever possible do not move thus the car.
• Do not apply hermetics containing silicone. The elements which have got to the engine of silicone in the engine do not burn down and damage a ljambda-probe.
• Security measures at removal of a fuel tank
• Before tank removal merge from it fuel or pump out fuel pump specially provided for this purpose.
• The fuel tank acts in film from the bottom party of the car. Before a detachment of collars of fastening of a tank bring to it from below a jack and linings.
• The empty tank is explosive and cannot be utilised in such kind. Before recycling the tank should be cut on a part. Watch that thus there was no spark.
• After tank installation into place start the engine and check up tightness of all connections.