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


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Basic elements

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

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

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

5–butterfly valve lever;
6–топливопровод high pressure;
7–fuel batcher;
8–pressure regulator.

For the best understanding of complete 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 from these a zaslonok it is connected by a cable of a drive of "gas" with a pedal in salon. It doses out a stream of inlet air in the engine. If the pedal of an accelerator is squeezed out more strongly, draft opens the second, big zaslonka. In the provision of full "gas" both zaslonka are open.

Proof-reader of composition of gas mixture

It represents the main component of system of injection and consists of a flowmeter of air and the fuel batcher. 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 klapanny lock rises because of a podsasyvaniye of pistons at an admission step, and that 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 zolotnik case. 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 klapanny lock – lets in the corresponding amount of fuel.

Pressure in system

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

Pressure regulator

The regulator of pressure is responsible for mix structure. It occurs as follows: intake of fuel to the bottom chambers (through which it is possible to affect quantity of a mix) occurs through a pressure regulator. If it passes a lot of fuel in the bottom chambers, pressure increases in the bottom chambers. Consequence: membranes of so-called valves of pressure differences cave in towards klapanny openings – towards vpryskny nozzles less fuel gets. On the contrary it, of course, operates in the same way.

Desirable result will reach: the amount of fuel changes in the ratio to arriving air – the 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.

Vprysknye of a nozzle

As soon as pressure of fuel reached 4,3 — 4,6 bar, nozzles submit gasoline to the canal in front of the valve of the corresponding cylinder. Thus they open to 2000 times a second thanks to what gasoline is sprayed is especially thin.

Control unit

The control unit regulates structure of a mix of the engine through a pressure regulator. In order that this management was based on something, the control unit obtains data on engine temperature, frequency of rotation, starting processes, the provision of a klapanny 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 an automatic transmission is added.

The control unit is located, as well as at all Audis 80, in car salon 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 thus the following: because of increased amount of air the flowmeter of air "believes" that the butterfly valve was a little slightly opened, and consequently provides respectively 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 of KE-III-Jetronic, namely according to frequency of rotation at present time. Thereby electronics aspires to return frequency of rotation to a standard range.

Starting fuel valve

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

Sensor of angular moving of a butterfly valve

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

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

Fuel interruption of supply in a mode of compulsory idling (movement nakaty)

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