Audi 80/Avant (B4)
Since 1991-1995 of release
Repair and car operation
+ The description
+ 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
- Systems of injection MPI and MPFI
Malfunctions and independent diagnostics
Check of separate elements
Removal of elements
Trosovyj drive of "gas"
Check of a mode of idling and the analysis of exhaust gases
The list of malfunctions
+ Transmission and transmission
+ Suspension bracket and steering
+ Brake system
+ Antiblocking system of brakes
+ Wheels and tyres
+ Kuzovnaja electrosystem
+ Ignition system
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ Body elements
+ Search of malfunctions
Systems of injection MPI and MPFI
Cхема in detail shows ignition and injection system on an example of system MPFI with the pressure gauge in an inlet collector. On a left-hand side gauges and the sensor controls influencing behaviour of the block of management are located. On the right components of systems of ignition and injection to which the management block sends the commands are presented.
Cистема injection MPI/MPFI with т.з. Fuel givings
Electronics helps to constrain a few "appetites" of the engine even the most powerful version Audi 80. However, at more than probable expense of fuel over 12 l on 100 km not always it is possible to be quite convinced that this good intention is carried out. But nevertheless follows that high capacity of the engine justifies this extra charge for high high-speed qualities of the car.
The 2,8-litre engine is supplied by system of injection with designation MPI. Behind this reduction English words Multi Point Injection – in Russian «multidot injection» disappear. (The Distinctive sign of system of injection MPI is a flowmeter of air in an air inlet sleeve behind on the right in a motor compartment).
For the best understanding of the general functioning of this system of injection it is necessary to get acquainted with separate problems of components at first.
The management block
Between arriving (from various gauges) the management block is the information and впрыскными atomizers. He allows the engine, depending on operating conditions of loading and temperature, to receive precisely certain quantity of fuel. For achievement of it the management block varies duration of opening of atomizers with an electromagnetic drive. As pressure in system of giving of fuel constantly remains almost invariable, the quantity of injected fuel can be regulated only by means of change of duration of injection. Whence the management block receives the information according to which he establishes this duration of injection? For it various gauges answer:
In an inlet collector of each cylinder of the engine is on one впрыскной to an atomizer. They deliver to corresponding cylinder quantity of fuel necessary at present and simultaneously provide thin dispersion of gasoline.
The fuel distributor
It is intended for uniform supply by fuel of all впрыскных atomizers. Besides, the fuel distributor operates and as the fuel store, thereby preventing pressure differences. The U-shaped form of the pipe, allowing a fuel supply to all is very interesting to six atomizers.
Regulator of pressure of giving of fuel
It is located behind on the right on the distributor of fuel and should – according to the name – to support constant level of pressure in the fuel distributor. It is carried out by means of more or less strong outflow of fuel back in a fuel tank on a drain highway. If on a drain highway leaves more fuel pressure decreases; if it is less – pressure raises.
The fuel pump and the relay
In more details about the electromagnetic fuel pump, the relay of the fuel pump and other relays MPI/MPFI you learn the Fuel tank and the fuel pump in the head.
On a way of a stream of soaked up air there is a wire which is warmed up электрически. Depending on the let in quantity the air stream changes that leads more or to less strong cooling of the mentioned wire. Temperature change leads to change of electric resistance of a wire which is measured by the management block.
The pressure gauge in an inlet collector
The pressure gauge in an inlet collector is in the block of management MPFI. Connection between an inlet collector and the gauge represents a thin hose. Pressure in an inlet collector is for the block of management a front view of the information for calculation of loading of the engine. It influences duration of injection and the ignition moment.
The gauge of temperature of inlet air
The gauge of temperature of inlet air is screwed in in the inlet channel of the third cylinder (behind on the right). In addition to the pressure gauge in an inlet collector it is for the block of management of a source инофрмации for loading calculation on the engine. At a heat of inlet air (that is equivalent low density of air) it is necessary to reduce, for example, duration of injection and to shift the ignition moment aside "later" a little.
The case of throttle knot
There, where the stream of soaked up air gets to an inlet collector of the engine, in one case there are two throttle заслонки. Smaller from заслонок it is connected by means of тросового a drive to an accelerator pedal. It doses out a stream of inlet air in the engine before position половинной loadings. By the further pressing a pedal of an accelerator the draught lever opens the second, big заслонку until in position of full loading there are no completely opened both заслонки.
Potentiometer throttle заслонки
The potentiometer throttle заслонки is put in action by the platen throttle заслонки. The potentiometer defines position throttle заслонки at present time and hands over to the management block this information in the form of electric resistance. The management block requires this information on loading, for example, for regulation of frequency of rotation in a mode of idling, a choice of the characteristic of ignition and calculation of duration of injection.
The valve of stabilisation of frequency of idling
As it is already clear under the name, this valve constantly provides constant frequency of rotation of a shaft of the engine in an idling mode – all the same, whether the engine is cold or heated-up, are included or not powerful consumers of the electric power of type of the conditioner.