Audi A4, S4
since 2000 of release
Repair and car operation
Audi A4, S4
+ Governing bodies and receptions of safe operation
+ Current leaving and service
+ Systems of cooling, 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/the 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. Turbokompressor
+ 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
+ Onboard electric equipment
Functioning of a control system and injection of the petrol engine
Elements of a control system of Motronic in a compartment of engines of 1.8 l (AVJ, BFB)
Fuel distributive highway and injectors. Engine of 1.8 l of AVJ/BFB
Control system elements in a compartment of V6 engines
Control system elements in a compartment of engines of the S4 model
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 pressure maintenance in the fuel system, equal 3.5, 4.0 or 6.0 atm., depending on the engine.
Through electrooperated injectors fuel impulsno is injected into the inlet pipeline located directly ahead of inlet valves of the engine. The control unit the engine makes consecutive management of injectors according to ignition order, regulates time of injection and, thereby, amount of injected fuel.
The air necessary for formation of a 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 soaked-up air is regulated by a butterfly valve which moves the step-by-step electric motor operated by the control unit of the engine. At turbirovanny engines soaked-up air is compressed by a turbokompressor actuated by exhaust gases of system of release. Then the compressed air is cooled in a cooler of forced air and arrives in the engine for formation of a fuel mix.
The volume of soaked-up air is defined by a measuring instrument of amount of air. The measuring instrument is located in the channel of soaked-up air. In the case of a measuring instrument the warmed touch plate cooled by a passable stream of soaked-up air is located thin, electricly. The electric current which is heating up a plate, is regulated by a control system so that to maintain temperature of a constant plate. If, for example, the amount of soaked-up air increases, the temperature of a heated-up plate starts to decrease. Thus the size of an electric current increases at once to keep temperature of a plate invariable. Fluctuations of an electric current of a plate indicate to the control unit by the engine its condition of loading that allows to define amount of injected fuel correctly.
The control unit defines optimum time of ignition, the moment of injection and amount of injected 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, provides optimum operation of the engine in any situation. If some sensors fail, the control unit is switched in a mode of the emergency program to exclude possible damage of the engine and to provide further movement of the car. In this case the engine works non-uniformly 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 screw in the block of cylinders at a flywheel. It hands over 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. It together with the sensor of provision of a cranked shaft hands over 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 base 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. It 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 butterfly valve potentiometer arrives.
Sensors of temperature of cooling liquid it is located in the thermostat case. It represents the resistor with the negative temperature factor which resistance decreases with temperature growth.
The sensor of temperature of 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 pairs which are forming as a result of heating of fuel accumulate. At operation of the engine of pair are sucked away from an adsorber and move in chambers of combustion of the engine.
Lambda probes (oxygen sensors) measure the content of oxygen in the fulfilled gases before and after the catalytic converter and transmit the corresponding signals in the control unit the engine. One lambda probe another is located before, and after the catalytic converter.
The sensor of a detonation will screw sideways in the block of cylinders. It interferes with emergence of dangerous shock combustion of a 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 capacity and torque is reached by means of the two-level switched inlet pipeline. Thus pipeline switching with short on the long occurs in a range of turns 2.000 – 3.700 in minute. The switching roller dividing by means of elastic sealing rings and sealing levels separate inlet channels, opens soaking-up path. Switching between provisions of a torque and capacities occurs электропневматически (depending on loading, number of turns and temperature) (address to illustrations below).
Instead of a usual drive of gas on a pedal of gas there is a sensor of provision of a pedal (an illustration lower) which hands over to the control unit the engine information on the provision of a pedal. On the basis of received information the control unit via the electric motor operates the provision of a butterfly valve.
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 the tension transferred to the control unit by the engine changes.
At failure of any sensor the lamp of malfunction of a drive of gas lights up and in memory of malfunctions of the control unit damage is registered. If out of operation there are both sensors, the engine works with the raised number of turns and does not react any more to a gas pedal.
The block of a 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, the power steering or the conditioner compressor.
The potentiometer of a butterfly valve is at a shaft of a butterfly valve and hands over to the control unit the current information on coal of provision of a zaslonka. The second potentiometer hands over to the control unit information on basic value and provides a spare signal at potentiometer failure.