Audi 80/Avant (B4)

since 1991-1995 of release

Repair and car operation



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
- Injection system
   + 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 a 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 electrosystem
+ ignition System
+ 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 soaking-up pistons of the engine, lifts the locking valve in an air flowmeter. Thanks to it the distributive piston allows fuel inflow to vpryskny nozzles. In operating time of a starter the starting fuel valve submits to admission system 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 arrive bypassing 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 frequency of rotation in a phase of warming up of the engine at the enriched mix.

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

Idling: for achievement of uniform frequency of rotation of a shaft of the engine in a mode of idling and soft acceleration performance in the bottom range of frequencies of rotation round each vpryskny nozzle in the chamber of combustion air arrives. 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 frequency of rotation falls below standard size.

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

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

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