Audi 80/Avant (B4)

since 1991-1995 release

Repair and operation of the car

Audi 80/Avant
+ Technical specification
+ Engines
+ System of production of the fulfilled gases
+ Cooling system
+ Fuel tank and fuel pump
+ Air filter and airintaking channels
- System of injection
   + System of injection of Mono-Motronic
   + System of injection of Digifant
   - System of injection of KE-III-Jetronic
      Basic elements
      Operating procedure
      Lambda regulation
      Malfunctions and independent diagnostics
      Independent repair
      Visual check
      Check of separate elements
      Search of malfunctions
      Removal of components
      Check of the mode of idling and analysis of exhaust gases
      List of malfunctions
   + Systems of injection of MPI and MPFI
+ Coupling
+ Transmission and transmission
+ Suspension bracket and steering
+ Brake system
+ Anti-blocking system of brakes
+ Wheels and tires
+ Body electrical system
+ System of ignition
+ Lighting
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ body Elements
+ Search of malfunctions
+ Specifications

Operating procedure

Interaction of components

Start: the depression created by the soaking-up engine pistons lifts the locking valve in an air flowmeter. Thanks to it the distributive piston allows inflow of fuel to vpryskny nozzles. In starter operating time the starting fuel valve gives to system of an admission additional amount of fuel – if the engine still cold. Only in this case the control unit allows similar injection. The maximum duration of injection also depends on temperature.

Phase of warming up of the engine: in order that the engine worked evenly the first minutes after start-up, the distributive valve of stabilization of idling opens the channel on which inlet air can come to round of a butterfly valve.

In addition the regulator of pressure lets in more fuel through nozzles. The increase in intake of air and fuel allows to reach the increased rotation frequency in a phase of warming up of the engine at the enriched mix.

With temperature increase of the engine the distributive valve blocks air access more and more. In parallel with this process the amount of the arriving fuel is normalized, the regulator of pressure reduces amount of injectable fuel.

Idling: for achievement of uniform frequency of rotation of a shaft of the engine in the mode of idling and soft acceleration performance in the lower range of frequencies of rotation round each vpryskny nozzle air comes to the combustion chamber. It leads to smaller dispersion of fuel. Air aspires to vpryskny nozzles via the connecting union in a head of the block of cylinders and the special air channel. The distributive valve for stabilization of frequency of rotation allows to arrive to bigger amount of inlet air bypassing a butterfly valve if the frequency of rotation falls below standard size.

Normal operation and acceleration of the car do not demand any special adaptations. The valvate lock in a flowmeter of air rises or falls depending on the arrived amount of air. Respectively intake of fuel to vpryskny nozzles changes: it is a lot of air – a lot of fuel, it is not enough air – not enough fuel. Thus, always the ratio, correct, most favorable to combustion process, absolutely automatically is established.

Full loading: the sensor of angular movement of a butterfly valve at completely squeezed out pedal of an accelerator signals the control unit that now from the engine the maximum power is required. Thereby the regulator of pressure receives command to give to vpryskny nozzles a little more fuel, than usually.

Interruption in supply of fuel in the mode of compulsory idling (the movement by a setup): function of interruption in supply of fuel in the mode of compulsory idling disconnects fuel supply if the car goes downhill and thus the accelerator pedal is not squeezed out.