Audi 80/Avant (B4)

Since 1991-1995 of release

Repair and car operation



Audi 80/Avant
+ The description
+ Engines
+ System of release of the fulfilled gases
+ Cooling system
+ Fuel tank and the fuel pump
+ The air filter and воздухозаборные channels
- Injection system
   + System of injection Mono-Motronic
   + System of injection Digifant
   - System of injection KE-III-Jetronic
      Basic elements
      Operating procedure
      Ljambda-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 the analysis of exhaust gases
      The list of malfunctions
   + Systems of injection MPI and MPFI
+ Coupling
+ Transmission and transmission
+ Suspension bracket and steering
+ Brake system
+ Antiblocking system of brakes
+ Wheels and tyres
+ Kuzovnaja electrosystem
+ Ignition system
+ Illumination
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ Body elements
+ Search of malfunctions
+ Specifications



Basic elements

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

Kind on the proof-reader of structure of a gas mixture of system of injection KE-III-Jetronic

1 – a pressure regulator;
2 – a potentiometer клапанного a shutter;
3 – an air inlet sleeve;
4 – the electromagnetic valve of a tank with the activated coal;

5 – the lever throttle заслонки;
6 – топливопровод a high pressure;
7 – дозатор fuel;
8 – a pressure regulator.

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

Throttle заслонка

In a final collector in a branch pipe there are two throttle заслонки. Smaller from these заслонок 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 accelerator pedal is squeezed out more strongly draught opens the second, big заслонку. In position of full "gas" both are opened заслонки.

The proof-reader of structure of a gas mixture

It represents the basic component of system of injection and consists of a flowmeter of air and дозатора fuel. They operate 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 клапанный the shutter rises because of подсасывания pistons at an admission step, and that more than more air passes from throttle заслонки. By means of system of levers the disk deviation is transferred дозатору fuel.
  • Дозатор fuel consists mainly of the distributive piston and the zolotnik case. For each cylinder of the engine in the zolotnik case there is a cut through which fuel gets in corresponding впрыскную an atomizer. The distributive piston opens or closes these cuts more or less and thus – depending on position клапанного a shutter – lets in corresponding quantity 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 дозаторе, топливопроводе and впрыскных atomizers.

Pressure regulator

The pressure regulator is responsible for mix structure. It occurs as follows: fuel receipt 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 pressure increases in the bottom chambers in the bottom chambers. A consequence: membranes of so-called valves of pressure differences cave in aside клапанных apertures – aside впрыскных atomizers gets less fuel. On the contrary it, of course, operates in the same way.

Desirable result will reach: the quantity of fuel changes in the ratio to arriving air – the mix is enriched or impoverished.

The pressure regulator receives commands from the management block. It occurs depending on ljambda-regulation, temperature of the engine and loading on it.

Vprysknye atomizers

As soon as pressure of fuel has reached 4,3—4,6 bar, atomizers submit gasoline to the channel 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.

The management block

The management block regulates structure of a mix of the engine through a pressure regulator. That this management on something was based, the management block obtains the data about engine temperature, frequency of rotation, starting processes, position клапанного a shutter (from idling to full loading). Here the ljambda-probe signal, and also the additional data from system of ignition, the gauge of atmospheric pressure and from an automatic transmission is added.

The management block is located, as well as at all Audi 80, in car salon on the right between the channel of heating and a partition to a motor compartment.

The distributive valve of stabilisation of idling

Function: the valve opens the air channel bypassing throttle заслонки. Effect thus following: because of the increased quantity of air air flowmeter "believes" that throttle заслонка was a little slightly opened, and consequently provides accordingly increased receipt of fuel. Desirable result: increase in frequency of rotation. How many will in addition arrive air, defines the block of management of system of injection KE-III-Jetronic, namely according to frequency of rotation at present time. Thereby electronics aspires to return frequency of rotation in a standard range.

The starting fuel valve

It is an atomizer with an electromagnetic drive which depending on engine temperature at start submits additional quantity of small sprayed fuel to an inlet collector. Duration of injection defines the block of management of system of injection KE-III-Jetronic.

The gauge of angular moving throttle заслонки

In Audi 80 two gauges of angular moving throttle заслонки are mounted. They signal the following data:

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

Fuel stopping delivery in a mode of compulsory idling (movement накатом)

Already mentioned regulator of pressure stops fuel giving if the car is maintained in a mode of compulsory idling. The management block distinguishes this mode under the information «frequency of rotation above, than frequency of rotation in an idling mode» and «is closed throttle заслонка».