Mercedes M-Class W163

since 1997 of release

Repair and car operation

Principle of functioning of a control system and injection of the petrol engine

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 fuel system in a range of 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 kanalevsasyvayemy 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

Arrangement of components of a control system of the engine on an example of models 163.154/172/174

1 — the Assembly block of safety locks and the relay 2 — the starter Relay 3 — the Relay of the fuel pump 4 — the Relay of a contour 15	5 — the Relay of the pump of a podmeshivaniye of secondary air (only American models) 6 — ECM (ME-SFI) 7 — the Diagnostic DLC socket 8 — the Sensor switch of a pedal of coupling (model with RKPP)

Arrangement of components of a control system of the engine on an example of models 163.154/172/174

Arrangement of components of a control system of the engine on an example of models 163.154/172/174

Arrangement of components of a control system of the engine on an example of models 163.154

Arrangement of components of a control system of the engine on an example of models 163.154

Location of separate elements of a control system on an example of separate models is shown by the engine on illustrations.

The sensor of provision of a cranked shaft (CKP) 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 (CMP) 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. The mechanism regulates the provision of a butterfly valve, providing stability of turns of idling, is not dependent on connection of additional consumers of energy, such as the steering amplifier or the К/В compressor.

The sensor of provision of a butterfly valve (TPS) is built in in the executive mechanism of a butterfly valve and issues on the control unit (ECM) information on the current coal of provision of a butterfly valve. The second potentiometer reports ECM data on base value and forms a spare signal at failure of a potentiometer of a butterfly valve.

The sensor of provision 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.

The sensor of temperature of cooling liquid (ECT) is located in the thermostat case. It represents the resistor with the negative temperature factor (NTC) which resistance decreases with temperature growth.

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

The system of ventilation of fuel tank/catching of fuel evaporations (EVAP) consists of a coal adsorber and the electromagnetic valve of management of a purge of the last. In an adsorber pairs of fuel which are forming as a result of its heating accumulate. At operation of the engine the fuel evaporations which have accumulated in an adsorber are extended to the inlet highway and go to 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 in the control unit the engine. One lambda probe another is located before, and after the catalytic converter.

The sensor (and) detonations (KS) is rolled directly in a body of the block of cylinders and serves for prevention of emergence of dangerous shock combustion of a fuel mix, allowing to hold installation of the moment of ignition on detonation border when efficiency of return of the engine is supported at a maximum level at the minimum fuel consumption.