Audi A4, S4

since 2000 release

Repair and operation of the car



Audi A4, S4
+ Introduction
+ Governing bodies and methods of safe operation
+ Current leaving and service
+ Engine
+ Cooling systems, heating and air conditioner
- Power supply systems, release and decrease in toxicity of the fulfilled gases
   + Power supply systems of petrol and diesel engines
   - System of injection of fuel of the petrol engine
      General information and security measures
      Functioning of a control system and injection of the petrol engine
      General check of system of injection of the petrol engine
      Check and adjustment of number of turns of the single course / moment of ignition/concentration WITH
   + System of injection of fuel of the diesel engine
   + Systems of release and decrease in toxicity of the fulfilled gases. Turbocompressor
+ Systems of electric equipment of the engine
+ Manual box of gear shifting
+ Automatic transmission
+ Coupling, power shafts and differential
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment






Functioning of a control system and injection of the petrol engine

Motronic control system elements in a compartment of engines of 1.8 l (AVJ, BFB)

1 — the Electromagnetic valve of 1 management of an adsorber
2 — the Lambda probe of the preliminary catalytic converter, 55nm
3 — the Lambda probe of the additional catalytic converter, 55nm
4 — the Combined valve of an admission of secondary air
5 — the Sensor of temperature of cooling liquid
6 — the Sensor of number of turns of the engine
7 — the Valve of an admission of secondary air
8 — the Holder of sockets under a broad tank of cooling liquid. For undocking of the plug disconnect a broad tank and incline it aside
9 — the Holder of sockets. Disunite the socket, poses. 8
10 — the Water-collecting compartment (electronics box). An installation site of the control unit of the engine with the built-in sensor of height, and also for the current relay of system of injection.
11 — the Water-collecting compartment (electronics box) with the relay of the pump of admixture of secondary air

12 — the pressurization pressure Sensor. In the top part of an interkuler
13 — the Control unit of a butterfly valve
14 — the Sensor of temperature of the soaked-up air
15 — the Circulating valve of a turbocompressor. It is located under the inlet pipeline
16 — the Sensor of a detonation 1
17 — the Sensor of a detonation 2
18 — the Hall Sensor
19 — the Injector
20 — the ignition Coil
21 — the Electromagnetic valve of restriction of pressurization
22 — the Measuring instrument of mass of air
23 — the Electric motor of the pump of secondary air

Fuel distributive highway and injectors. Engine of 1.8 l of AVJ/BFB

31 — the Screw, 10nm
32 — the Protective cover
33 — the Lock bracket. Watch the correct situation on an injector and the fuel distributive highway
34 — the Inlet pipeline with the control unit of a butterfly valve and the sensor of temperature of the soaked-up air
35 — the Insert for an injector, 3nm. It is rolled on means for fixing of a carving of D000600A2
36 — the Sealing ring. Surely replace. Before installation oil the pure motive.

37 — the Injector
38 — the Sealing ring. Surely replace Before installation oil the pure motive.
39 — the fuel supply Pipeline, 25nm
40 — the Fuel distributive highway
41 — the Socket

Control system elements in a compartment of V6 engines

1 — the EVAP Sensor
2 — EVAP purge Valve
3 — the fuel pressure Regulator
4 — the ECT Sensor
5 — Warmed up a lambda probe
6 — the CKP Sensor
7 — the Sensor of a detonation 2
8 — the Sensor of speed of rotation of a cranked shaft
9 — ignition Coils
10 — the Injector
11 — the Sensor of a detonation 1

12 — the IAC Valve
13 — the Switching valve of an inlet air duct
14 — TPS
15 — EGR temperature Sensor
16 — Em the valve of management of depression of EGR
17 — PCM
18 — the CMP Sensor
19 — Warmed up a lambda probe
20 — the MAF Sensor
21 — the Output cascade of the coil of ignition

Control system elements in a compartment of engines of the S4 model

1 — the electrical wiring Socket a lambda probe 1 behind the catalytic converter
2 — the electrical wiring Socket a lambda probe 2 behind the catalytic converter
3 — the Socket of an electrical wiring warmed up a lambda probe in the block 1
4 — the detonation sensor electrical wiring Socket in the block 1
5 — the ECT Sensor
6 — Perepuskna the adjusting valve of system of production of the fulfilled gases
7 — EVAP purge Valve
8 — temperature No. 1 Sensor on release
9 — Em the valve of an additional admission of air
10 — E / the motor of the pump of an additional admission of air
11 — temperature No. 2 Sensor on release
12 — the Valve of circulation of a turbocompressor
13 — the air pressure Regulator
14 — the block 2 CMP Sensor
15 — the Relay of the pump of an additional admission of air
16 — ECM
17 — the Socket of an electrical wiring of the sensor of speed of rotation of a cranked shaft
18 — the detonation sensor electrical wiring Socket in the block 2
19 — the Socket of an electrical wiring warmed up a lambda probe in the block 2

20 — Em the valve of adjustment of a camshaft in the block 2
21 — the Module of control of the valve of a butterfly valve
22 — the Sensor of pressure of the forced air
23 — the block 1 CMP Sensor
24 — the Output cascade of the coil of ignition in the block 2
25 — the Output cascade of the coil of ignition in the block 1
26 — Em the valve of adjustment of a camshaft in the block 1
27 — the Socket of an electrical wiring warmed up a lambda probe in the block 2
28 — the detonation No. 1 Sensor
29 — the detonation No. 2 Sensor
30 — the VSS Sensor, in transmission
31 — Warmed up a lambda probe in the block 2
32 — Coils of ignition of the block 2
33 — block 2 Injectors
34 — the IAT Sensor
35 — the IAT sensor electrical wiring Socket
36 — block 1 Injectors
37 — Coils of ignition of the block 1
38 — the MAF Sensor

Fuel is sucked in from a fuel tank by the electric fuel pump and moves via the fuel filter to the fuel distributive highway. The regulator of pressure provides maintenance of pressure in fuel system, equal 3.5, 4.0 or 6.0 atm., depending on the engine.

Through the electrooperated injectors fuel pulsewise is injected into the inlet pipeline located just before inlet valves of the engine. The control unit of the engine makes consecutive management of injectors according to an ignition order, regulates time of injection and, thereby, amount of injectable fuel.

The air necessary for formation of fuel mix is sucked in by the engine via the air filter and arrives through a butterfly valve and the inlet pipeline to inlet valves. The amount of the soaked-up air is regulated by a butterfly valve which moves the step electric motor operated by the engine control unit. At turbocharged engines the soaked-up air compresses the turbocompressor set in motion by exhaust gases of system of release. Then compressed air is cooled in a cooler of the forced air and comes to the engine for formation of fuel mix.

The volume of the soaked-up air is defined by the measuring instrument of amount of air. The measuring instrument is located in the channel of the soaked-up air. In the case of the measuring instrument the thin, electrically warmed touch plate cooled by the passing stream of the soaked-up air is located. The electric current heating a plate is regulated by a control system so that to maintain constant plate temperature. If, for example, the amount of the soaked-up air increases, temperature of the heated plate starts decreasing. Thus the size of electric current at once increases to keep temperature of a plate invariable. Fluctuations of electric current of a plate indicate to the control unit of the engine its condition of loading that allows to define amount of injectable fuel correctly.

The control unit defines optimum time of ignition, the moment of injection and amount of injectable fuel. Thus there is a coordination of operation of the control unit with other systems of the car, for example, to management of a transmission or anticreeping system.

Information from other sensors and the operating tension arriving to executive bodies ensures optimum functioning of the engine in any situation. If some sensors fail, the control unit switches in the mode of the emergency program to exclude possible damage of the engine and to provide the further movement of the car. In this case the engine works unevenly and at increase in gas has tendency to a stop.

Sensors and executive mechanisms of system of injection

The sensor of provision of a cranked shaft will be screwed in the block of cylinders at a flywheel. He transfers to the control unit information on number of turns of the engine and position VMT of the piston of the first cylinder.

The sensor of provision of a camshaft is located in an end face of a cover of a head of cylinders. He together with the sensor of provision of a cranked shaft transfers to the control unit information on VMT of the piston of the first cylinder. It serves for synchronization of the moment of ignition and sequence of ignition.

The potentiometer of a butterfly valve is located in the executive mechanism of a butterfly valve and gives the control unit information on the current coal of provision of a butterfly valve. The second potentiometer gives the control unit information on basic value and forms a spare signal at failure of a potentiometer of a butterfly valve.

The sensor of a pedal of an accelerator is located the region of an arrangement of feet of the driver directly on a pedal axis. He gives the control unit information on the provision of a pedal. For reliability reasons from the sensor of a pedal the duplicating signal, just as from a potentiometer of a butterfly valve arrives.

Sensors of temperature of cooling liquid it is located in the thermostat case. It represents the resistor with negative temperature coefficient which resistance decreases with growth of temperature.

The sensor of temperature of the soaked-up air also represents the NTC resistor.

The system of ventilation of a fuel tank consists of an adsorber and the electromagnetic valve. In an adsorber fuel couples which are formed as a result of fuel heating accumulate. During the operation of the engine of couple are sucked away from an adsorber and move in engine combustion chambers.

Lambda probes (oxygen sensors) measure the content of oxygen in the fulfilled gases before and after the catalytic converter and transmit the corresponding signals to the control unit of the engine. One lambda probe another is located before, and after the catalytic converter.

The sensor of a detonation will be screwed sideways in the block of cylinders. It interferes with emergence of dangerous shock combustion of fuel mix. Thanks to it the moment of ignition can keep on detonation border that provides effective use of energy of combustion of fuel and by that reduces fuel consumption.

The switched inlet pipeline (the engine of 2.0 l of ALT)

The necessary characteristic of power and torque is reached by means of the two-level switched inlet pipeline. Thus switching of the pipeline with short on the long happens in the range of turns of 2.000 - 3.700 in the min. The switching roller dividing certain inlet canals by means of elastic sealing rings and sealing levels opens the soaking-up path. Switching between provisions of a torque and power happens electric air (depending on loading, number of turns and temperature) (address to illustrations below).

The inlet pipeline in the provision of optimization of a torque

1 — the Switching roller
2 — the vacuum Accumulator. On the engine of 2.0 l of FSI AWA is in the inlet pipeline

The inlet pipeline in the provision of optimization of power

Accelerator servo-driver

Instead of the ordinary drive of gas on a pedal of gas there is a sensor of provision of a pedal (an illustration lower) which transfers to the control unit of the engine information on the provision of a pedal. On the basis of the received information the control unit via the electric motor operates the provision of a butterfly valve.

Accelerator pedal sensor

1 — a gas Pedal
2 — the Path resistive
3 — the Sensor 1+2

In the case of the sensor of situation there are two contact potentiometers which are fixed on the general to a shaft. At each change of provision of a pedal resistance of potentiometers and tension transferred to the control unit of the engine changes.

At failure of any sensor the lamp of malfunction of the drive of gas lights up and in memory of malfunctions of the control unit damage is registered. If both sensors fail, the engine works with the raised number of turns and does not react to a gas pedal any more.

The block of the drive of a butterfly valve (address to an illustration below) turns on in the structure the electric motor, two potentiometers and system of cogwheels with a returnable spring. It regulates the provision of a butterfly valve. A problem of the control unit is stabilization of turns of idling, irrespective of connection of additional consumers, such as, of the power steering or the compressor of the conditioner.

Block of the drive of a butterfly valve

1 — the Case of a butterfly valve
2 — the Drive of a butterfly valve
3 — a case Cover with the built-in electronics
4 — the Butterfly valve
5 — the Potentiometer of a butterfly valve (the corner sensor 1+2 drives of a butterfly valve)
6 — the Gear wheel with spring return

The potentiometer of a butterfly valve is at a shaft of a butterfly valve and transfers to the control unit the current information on coal of position of the gate. The second potentiometer transfers to the control unit information on basic value and provides a spare signal at failure of a potentiometer.











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