Audi S4

since 2000 release

Repair and operation of the car



Audi S4
+ Introduction
+ Governing bodies and methods of safe operation
+ Current leaving and service
+ Engine
+ Cooling systems, heating and air conditioner
- Power supply systems, release and decrease in toxicity of the fulfilled gases
   - Power supply systems of petrol and diesel engines
      General information and security measures
      Dropping pressure in fuel system
      Removal and installation of the fuel pump with the fuel reserve sensor
      Removal of air from fuel system (the petrol engine of 1.8 l)
      Removal and installation of the fuel filter
      Removal and installation of the air filter
   + System of injection of fuel of the petrol engine
   + System of injection of fuel of the diesel engine
   + Systems of release and decrease in toxicity of the fulfilled gases. Turbocompressor
+ Systems of electric equipment of the engine
+ Manual box of gear shifting
+ Automatic transmission
+ Coupling, power shafts and differential
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment





Dropping pressure in fuel system


Before getting to work, get acquainted with the precautionary measures given in the section General information and security measures.

After implementation of the procedure described below you will only take off excessive pressure in fuel system. In pipelines there will be a gasoline. Before disconnecting any fuel hose, take all necessary precautionary measures.

The fuel system considered in this Chapter consists of the fuel tank located in it the fuel pump with the sensor of a reserve of fuel, the fuel filter, injectors or nozzles, the regulator of pressure and various hoses and tubes. In all these knots in operating time of the engine (and also at the included ignition) fuel is under pressure.

After switching off of ignition pressure in system remains still quite long time. Before a detachment of any of mentioned above a component pressure needs to be taken off.

For this purpose quickly open a cover of the fuel tank and again close it. Put a thick rag on connection. Use goggles. In system of direct injection of the AWA engine by the described image pressure only regarding the system having low pressure can be taken off (to 6 atm.). For removal of high pressure (to 110 atm.) special devices are required. High pressure in system is present at area from TNVD to nozzles. At the diesel engine of 1.9 l temperature of fuel pipelines and fuel at the engine about the pump nozzles in extreme cases can make up to 100 °C. Before opening of connections, let's fuel cool down since otherwise it can occur a burn.

The simplest way of dumping of pressure is following. Take a safety lock of the fuel pump and start the engine. If the engine is not started, turn it a starter within several seconds and if it is started, allow the engine to work at single turns until he does not decay. Completely to dump pressure, turn the engine crankshaft a starter on couple of turns. Switch off ignition and return into place a pump safety lock.

Keep in mind that if pressure is dumped (or fuel is removed from system), start of the engine will take bigger, than usually, time. You should turn the engine crankshaft a starter at least several seconds during which pressure in system will be restored, and fuel will fill all pipelines.