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 Mono-Motronic
   + System of injection Digifant
   - System of injection 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
+ Signaling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ Body elements
+ Search of malfunctions
+ Specifications





Basic elements

Scheme of action of system of injection KE-III-Jetronic. Red fuel is shown, the arriving air is emitted light pink.

Look on the proofreader of composition of gas mixture of system of injection of KE-III-Jetronic

1 – pressure regulator;
2 – potentiometer of a valvate lock;
3 – air inlet sleeve;
4 – the electromagnetic valve of a tank with absorbent carbon;

5 – lever of a butterfly valve;
6 – fuel-supply line of high pressure;
7 – fuel batcher;
8 – pressure regulator.

For the best understanding of full functioning of our system of injection for a start it is necessary to explain the major details and concepts:

Butterfly valve

In a final collector in a branch pipe there are two butterfly valves. Smaller of these gates it is connected by a cable of the drive of "gas" with a pedal in salon. It doses a stream of inlet air in the engine. If the pedal of an accelerator is squeezed out stronger, then draft opens the second, big gate. In the provision of full "gas" both gates are open.

Proofreader of composition of gas mixture

It represents the main component of system of injection and consists of a flowmeter of air and the batcher of fuel. They act so:

  • The easy tin disk of a flowmeter of air is in the middle of the air stream which is soaked up by the engine. This valvate lock rises because of a podsasyvaniye of pistons at an admission step, and the it is more, than more air passes from a butterfly valve. By means of system of levers the deviation of a disk is transferred to the fuel batcher.
  • The batcher of fuel consists mainly of the distributive piston and the case of a zolotnik. For each cylinder of the engine in the case of a zolotnik there is a cut through which fuel gets to the corresponding vpryskny nozzle. The distributive piston opens or closes these cuts more or less and thus – depending on the provision of a valvate lock – lets in the corresponding amount of fuel.

Pressure in system

The fuel pump in the fuel tank pumps over fuel under pressure in system of injection. The first instance is the regulator of system pressure in the separate case here. It reduces elevated pressure and leaves for fuel system only from 6,1 to 6,5 bars. This pressure, pressure in system, works in the batcher, a fuel-supply line and vpryskny nozzles.

Pressure regulator

The regulator of pressure is responsible for composition of mix. It occurs as follows: intake of fuel to the lower cameras (via which it is possible to affect amount of mix) happens via pressure regulator. If it passes a lot of fuel in the lower cameras, then pressure increases in the lower cameras. Investigation: membranes of so-called valves of pressure differences cave in towards valvate openings – towards vpryskny nozzles less fuel gets. On the contrary it, of course, works in the same way.

The desirable result is achieved: the amount of fuel changes in the ratio to the arriving air – mix is enriched or impoverished.

The regulator of pressure receives commands from the control unit. It occurs depending on a lambda regulation, temperatures of the engine and load of it.

Vpryskny nozzles

As soon as pressure of fuel reached 4,3 — 4,6 bars, nozzles give gasoline to the canal in front of the valve of the corresponding cylinder. At the same time they open to 2000 times a second thanks to what gasoline is sprayed especially thinly.

Control unit

The control unit regulates composition of mix of the engine via pressure regulator. In order that this management was based on something, the control unit obtains data on engine temperature, rotation frequency, starting processes, the provision of a valvate lock (from idling to full loading). Here the signal a lambda probe, and also additional data from system of ignition, the sensor of atmospheric pressure and from the automatic transmission is added.

The control unit is located, as well as at all Audis 80, in interior of the car on the right between the channel of heating and a partition to a motor compartment.

Distributive valve of stabilization of idling

Function: the valve opens the air channel bypassing a butterfly valve. Effect at the same time following: because of the increased amount of air the flowmeter of air "believes" that the butterfly valve was a little slightly opened and therefore provides respectively the increased intake of fuel. Desirable result: increase in frequency of rotation. How many will in addition arrive air, defines the control unit of system of injection KE-III-Jetronic, namely according to rotation frequency of time at present. Thereby electronics seeks to return rotation frequency to standard range.

Starting fuel valve

It is a nozzle with the electromagnetic drive which depending on engine temperature at start gives additional amount of small sprayed fuel to an inlet collector. Duration of injection defines the control unit of system of injection KE-III-Jetronic.

Sensor of angular movement of a butterfly valve

In Audi 80 two sensors of angular movement of a butterfly valve are mounted. They signal the following data:

  • Idling; for regulation of frequency of rotation of idling, interruption in supply of fuel in the mode of compulsory idling; completely electronic system of ignition, etc.
  • Full gas; for enrichment of gas mixture in the mode of full "gas" and completely electronic system of ignition.

Interruption in supply of fuel in the mode of compulsory idling (the movement by a setup)

Already mentioned regulator of pressure stops fuel supply if the car is operated in the mode of compulsory idling. The control unit distinguishes this mode according to information "the frequency of rotation higher, than rotation frequency in the idling mode" and "is closed a butterfly valve".








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