Mercedes C-Class

W203 since 2000 of release

Repair and car operation



Mercedes-Benz
+ Mercedes-Benz Cars of a class C (W-203)
+ Operation manual
+ Routine maintenance
+ Engine
+ cooling and heating Systems
- Power supply system and release
   + Power supply system of the petrol and diesel engine
   - System of injection of fuel of the petrol engine
      Security measures at work with system of injection of the petrol engine
      Functioning of a control system and injection of the petrol engine
      General check of system of injection of the petrol engine
      Removal and installation of a measuring instrument of weight of air
      Check of injectors
      Removal and installation of the fuel distributive highway and injectors
      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. Turbokompressor
   + Systems of release and decrease in toxicity of the fulfilled gases. Turbokompressor
+ engine Electric equipment
+ Manual transmission
+ Automatic transmission
+ Coupling and power shafts
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment







Functioning of a control system and injection of the petrol engine

Arrangement of components in an impellent compartment of the models C240 and С320

1 — the Sensor of a detonation (KS) 1 (On the right on the engine)
2 — the Sensor of a detonation (KS) 2 (At the left on the engine)
3 — the Sensor of provision of a butterfly valve (TPS)
4 — the Vacuum EGR transmitter
5 — the Valve switch of a configuration of the inlet pipeline
6 — the Sensor of temperature/quality/level of oil

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 3.2 – 3.6 atm.
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 injection time and by that 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 compressor engines soaked-up air is compressed by the compressor actuated from klinoremenny transfer. 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 the engine is in electronics box, at the left, about the tank of brake liquid or is direct on the engine. 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 bodies 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 executive mechanism of a butterfly valve consists of the electric motor and two potentiometers. It regulates the provision of a butterfly valve. Thanks to it the stable number of turns of idling is reached, is not dependent on connection of additional consumers, such as, the power steering or the conditioner compressor.

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 gas is located the region of an arrangement of feet of the driver directly on an axis of a pedal of gas. It gives the control unit information on the provision of a pedal. For safety reasons from the sensor of a pedal the additional signal, just as from a butterfly valve potentiometer undertakes.

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 in the block of cylinders, near a directing tube. 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.