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



Operating procedure

Cold start: the valve of stabilisation of idling allows to let in air quantity in addition to air arriving in the regular way. Simultaneously the management block receives from the gauge of temperature of a cooling liquid the information «the cold engine». On the basis of all this data the management block counts long opening впрыскных atomizers for preparation of richer mix. Besides, for short time the management block activates the starting valve for receipt of an additional portion of fuel.

Phase of warming up of the engine: the gauge of temperature of a cooling liquid informs raising temperature of a cooling liquid further to the management block. That in turn makes the order about closing of the valve of stabilisation of idling, duration of giving of fuel atomizers decreases to the usual.

Idling: from messages of a potentiometer throttle заслонки and a potentiometer on a flowmeter of air the management block distinguishes, when the engine works in an idling mode. If frequency of rotation in an idling mode falls, the management block changes the ignition moment; simultaneously opens the air channel the valve of stabilisation of idling thanks to what the quantity of injected fuel increases.

Normal operation does not demand any special adaptations. Duration of opening впрыскных atomizers is defined by position throttle заслонки and клапанного a shutter in air flowmeter.

Acceleration: fast opening throttle заслонки a monitor distinguishes under messages of a potentiometer throttle заслонки as acceleration. Accordingly duration of injection increases by short time.

Ljambda-regulation: каталитическому constant change of the enriched or impoverished mix is necessary for excellent job for neutralizer. The maintenance of residual oxygen to time transfers at present a ljambda-probe (it is located in каталитическом neutralizer) to the block of management which gives to fractions of a second впрыскным to atomizers the order on shorter or more long time of injection and, thereby, quantity of fuel.

Fuel stopping delivery in a mode of compulsory idling: the information on removal of a foot from an accelerator pedal again gets through a potentiometer throttle заслонки to the management block. If simultaneously the gauge of temperature of a cooling liquid informs that the engine has reached the working temperature, and the Hall gauge in the distributor informs that frequency of rotation of the engine makes more than 1500 rpm the block of management does not give the order on opening впрыскных atomizers.

Full loading: for total power development at completely squeezed out pedal of an accelerator it is necessary for the engine of more fuel. On the basis of the message «full gas» from a potentiometer throttle заслонки in a combination with completely opened клапанным a shutter the management block distinguishes a condition of "full loading» and increases duration of injection of atomizers, and the ljambda-probe signal is thus ignored.

Restriction of frequency of rotation: for protection against excess of as much as possible admissible frequency of rotation of a shaft of the engine the management block disconnects впрыскные atomizers if the Hall gauge informs on frequency of rotation 6400 – 6500 rpm.

Work at state of emergency: if the signal from one of suppliers of the information does not come absolutely or has a senseless indicator the system of injection Digifant and in these conditions is not beaten out from a normal course of work. The management block chooses the so-called spare indicator which has been already written down in memory. It, of course, cannot consider many service conditions, but the car all the same remains on the move. The driver can distinguish absence of a signal from the gauge on insufficient capacity or bad starting properties.