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
   + 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

Injection system

System of injection of Mono-Motronic

Function chart of system of injection of Mono-Motronic


In drawing the vpryskny nozzle (2) with even connected tip (1), (3) blocks of preparation of gas mixture taken from a nest is shown. Sideways on the valve the fuel strainer is visible.

The disassembled regulator of pressure:

4–basic surface.

The regulator of provision of a butterfly valve (1) can be removed separately. It is necessary, if the driving pusher of the switch of a signal of idling (2) is faulty. The position (3) designates a persistent bolt of a butterfly valve.

The potentiometer of a butterfly valve is established and regulated at plant and it cannot be assorted. We only removed it to show you sliding contacts and carrying-out paths. In case of malfunction it is necessary to replace the block of preparation of gas mixture.

Central injection

The smallest Audi engine is equipped with system of injection of gasoline through one nozzle and a butterfly valve, so-called system Mono-Motronic. It consists generally of the case similar to the case of the carburetor and supplied with the one and only vpryskny nozzle. The fuel exit from a nozzle is regulated by the electronic control unit which at the same time provides management of regulation of an advancing of ignition. In more detail about Mono-Motronic system you learn in head ignition System.

Basic elements

Control unit

It is located in feet of the forward passenger in front of the heating channel and via the multicontact tip receives information from the following knots:

  • The Hall sensor in the ignition distributor – about frequency of rotation of the engine.
  • Lambda probe in catalytic converter – about the content of residual oxygen in the fulfilled gases.
  • Potentiometer – about the provision of a butterfly valve and by that amount of arriving air.
  • The sensor of temperature of arriving air on an entrance of the block of preparation of gas mixture – about temperature of arriving air.
  • The temperature sensor on a branch pipe of cooling liquid at the left on a head of the block of cylinders – about temperature of cooling liquid.

Processing entering signals the control unit counts duration of opening of a vpryskny nozzle with an electromagnetic drive and by that amount of injected fuel. Thus the control unit uses multiparameter characteristics of the engine – the file in which all possible conditions of the engine are written down. In the same place in the form of electric signals data relating to this or that situation on amounts of fuel are written down. In addition in the form of characteristics in Mono-Motronic indicators of the moments the ignitions relating to amount of fuel and an operational situation are kept.

Butterfly valve

It is located at the very bottom of the block of preparation of gas mixture and regulates amount of air which the engine should receive.

Extent of opening of a zaslonka is defined by the driver by pressing an accelerator pedal. The pedal and a butterfly valve are directly connected with each other by means of a hummock drive of an accelerator.

Block of preparation of gas mixture

The majority of details of the central system of injection of gasoline are collected in this case. Through it passes arriving air, and here – by means of a nozzle – fuel, as well as in the carburetor is added.

Vpryskny nozzle

It opens by means of an electromagnet. Thus fuel can arrive – or not – depending on a signal from the control unit. For optimum dispersion of fuel the nozzle is supplied with slanted final openings through which gasoline gets on a conic wall of a final opening, завихряясь there.

The Vpryskny nozzle can open and be closed only, but unable to dose out amount of fuel. Therefore its regulation occurs on injection time. It is carried out as follows: the nozzle injects once at each impulse of a high-tension current from the Hall sensor. If a small amount of fuel is required, the nozzle opens at this impulse only for short time – frequent more shortly, than on one thousand seconds. If the engine needs more fuel (at cold start or full loading), injection occurs during more long time. And so at each impulse of the sensor of the Hall.

The sensor of temperature of arriving air

It is located sideways on the case of a nozzle and thus can precisely define the air temperature, preparation of gas mixture arriving in the block.

Pressure regulator

The fuel pump under pressure submits gasoline to a regulator of pressure which provides intake of gasoline to a nozzle under the same pressure 0,8 – 1,2 bar. For this purpose he allows a most or smaller part of gasoline to go back to a fuel tank on the drain highway. Giving via the fuel filter remains almost constant.

Regulator of provision of a butterfly valve

The small electric motor with angular transfer moves a driving pusher closer or farther from an emphasis of idling of a butterfly valve. Thus, depending on a situation the butterfly valve can open on big or smaller size.

Thanks to it frequency of rotation of idling remains to a constant at various loadings. Ahead in a driving pusher of a regulator of provision of a butterfly valve the so-called switch of a signal of idling which reports to the control unit if you release an accelerator pedal is located. This signal is necessary for stabilization of frequency of rotation of idling.

Butterfly valve potentiometer

He reports to the control unit about movements of a butterfly valve and its situation. So, for example, fast opening of a butterfly valve is distinguished as car acceleration. If you clean a foot from an accelerator pedal, the signal of closing of a butterfly valve activates fuel interruption of supply in an idling mode. The message passes in a type of an electric signal – the potentiometer represents not that other as variable resistance.