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
      Operating procedure
      Malfunctions and independent diagnostics
      Independent repair
      Visual check
      Check of separate elements
      Removal впрыскных atomizers
      Check of a mode of idling and the analysis of exhaust gases
      The list of malfunctions
   + System of injection KE-III-Jetronic
   + 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


System of injection Digifant

On this illustration the system of injection Digifant with its components is schematically presented. White arrows show air way, supply by fuel is presented by red colour.

1 – a fuel tank;
2 – the fuel filter;
3 – a pressure regulator;
4 – the fuel distributor;
5 – an atomizer;

6 – an inlet collector;
7 – air flowmeter;
8 – the valve of stabilisation of idling;
9 – the fuel pump.

Multidot injection

For possible more exact distribution of a mix of fuel/air the injection system in which each cylinder has own впрыскную an atomizer, than that in which injection is carried out only by one central atomizer is better approaches. Therefore the engine capacity of 85 Kw is supplied by the multidot (distributed) system of injection. It is a question about электронно to operated system with the programmed characteristic of injection, with operated system of ignition, with the moment of ignition regulated on a detonation, with the integrated stabilisation of frequency of rotation in a mode of idling and with a fuel stopping delivery in a mode of compulsory idling.

To whom the name of this system of injection reminds a word Elefant (elephant), that is at all near from true. Engineers-electronics engineers Volkswagen and Audi took this name from a white elephant (weiber Еlefant) – among programmers so name Jacks of all trades. New word-formation – Digitaler Elefant.

Basic elements

The management block

The management block receives through the multicontact tip following types of information from:

    Starter from the plug 50 – about the beginning and the termination of process of start. Potentiometer throttle заслонки – about current position throttle заслонки. The Hall gauge in the ignition distributor – about frequency of rotation of the engine. Ljambda-probe in каталитическом neutralizer – about the maintenance of residual oxygen in the fulfilled gases. Potentiometer in air flowmeter – about position of the retaining valve (quantity of let in air). The gauge of temperature of inlet air in air flowmeter. The gauge of temperature of a cooling liquid in a branch pipe of system of cooling. The gauge of detonation combustion on the block of cylinders for "detonation" combustion, the ignition System see also the head.

On the basis of information on frequency of rotation and loading the management block counts duration of opening electromagnetic впрыскных atomizers and by that injected quantity of fuel. For this purpose at the disposal of the management block there are characteristics of injection and in addition the ignition characteristic. These characteristics represent meeting of the data for every possible situations at operation of the engine and corresponding quantities of fuel, and also the ignition moments. These indicators the management block can change after receipt of so-called adjustment signals (for example temperatures of inlet air and cooling liquid).

Throttle заслонка

Two throttle заслонки are in a branch pipe in an inlet collector. 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.

Potentiometer throttle заслонки

The potentiometer throttle заслонки covers position throttle заслонки at present from "idling" (throttle заслонка it is closed) to full loading (throttle заслонка is completely open). On the basis of its information idling stabilisation, a fuel stopping delivery in a mode of compulsory idling or gas mixture enrichment at full opening throttle заслонки is activated.

Pressure regulator

It is located in front of the distributor of fuel and regulates pressure of giving of fuel to впрыскным to atomizers. For this purpose it receives the information on a depression condition in an inlet collector. At closed throttle заслонке and high depression it keeps lower pressure in an idling mode. At depression decrease at большей to loading of the engine the pressure regulator increases pressure of giving of fuel. The fuel pump submits fuel with higher working pressure, but thanks to a regulator of pressure of plums of gasoline back in a fuel tank accordingly increases or, if necessary, decreases.


At each turn of a cranked shaft they inject gasoline in впрыскной the channel in front of the inlet valve of the corresponding cylinder – duration of this process defines the management block. The corresponding cylinder receives one portion for emergency, and the second at the open inlet valve directly in the combustion chamber.

The gauge of temperature of arriving air

It is located sideways in a flowmeter of air and thus can is exact define temperature of arriving air. The temperature of inlet air gets to the block of management in the form of a resistance indicator. This indicator is necessary for an optimum dosage of fuel.

The gauge of temperature of a cooling liquid

The temperature of a cooling liquid is necessary for management of many functions of injection: enrichment of a starting mix, послестартовое enrichment (on all range of temperatures), enrichment at acceleration and switching-off of giving of fuel in a mode of compulsory idling (movement накатом). The information on temperature of a cooling liquid arrives in the management block also in the form of a resistance indicator. The management block counts necessary duration of injection which at разогретом to working temperature the engine is in a range between two and восемью milliseconds. This indicator can increase to 70 % if the temperature of a cooling liquid reaches-25S.

Air flowmeter

Air necessary for combustion arriving from the air filter, more or less (depending on the let in quantity) wrings out aside клапанный a shutter in air flowmeter, thus the valve of attenuation connected with клапанным by a shutter, prevents fluctuations клапанного a shutter. The potentiometer directs to the block of management depending on position клапанного a shutter a signal in the form of pressure: a high voltage at full opening and air considerable quantity, small pressure at small opening.

The starting fuel valve

This впрыскная an atomizer with an electromagnetic drive injects in впрыскной a collector additional quantity of fuel during 1—4 with depending on engine temperature at start. Duration of injection defines the block of management of system of injection Digifant.

The valve of stabilisation of idling

In a warming up phase, at full turn of the amplifier of the steering mechanism, at the working conditioner or at the included step of an automatic transmission this valve releases the additional air channel, bypassing thereby throttle заслонку.

The strengthened air exchange in a direction of an inlet collector simultaneously leads to the strengthened giving of fuel. So the raised friction in the engine in a cold condition or higher loading on the engine, caused by the pump of the amplifier of a wheel spending energy, the conditioner compressor, and also an automatic transmission is counterbalanced.

The valve of stabilisation of frequency of rotation of a shaft of the engine in an idling mode is used and in a mode of compulsory idling. He allows to arrive to quantity of air necessary for movement at closed throttle заслонке.