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The principle of operation of the control system and injection petrol engine

general information

Fuel is sucked from the fuel tank electric fuel pump and is supplied through the fuel filter to the fuel distribution manifold. The pressure regulator maintains the pressure in the fuel system in the range of 3.2 ÷ 3.6 atm.

Through Power fuel injector pulse is injected into the intake pipe, located directly in front of the intake valves of the engine. The engine control unit produces a consistent control of injectors according to the order of ignition, adjusts the injection time and thus the amount of fuel injected.

The air required for the formation of fuel mixture sucked in the engine through the air filter and flows through the throttle valve and the intake pipe to the intake valves. The amount of intake air is regulated by a throttle valve, which moves stepper motor controlled by the engine control unit. At compressor engine intake air compressed by the compressor, driven by belt transmission from. The compressed air is cooled in the charge air cooler and is supplied to the engine to form a fuel mixture.

The volume of the intake air quantity of air is determined by the meter. The meter is located in the intake air passage. The meter body is thin, electrically heated sensor plate cooled by passing a stream of intake air. Electric current heater plate, a control system is regulated so as to maintain the temperature of the plate constant. If, for example, the amount of intake air increases, the temperature of the heater plate begins to decline. The magnitude of the electric current immediately increases to maintain the temperature of the plate constant. Fluctuations in the electric current of the plate indicates the engine control unit on its load status, which allows you to properly determine the amount of fuel injected.

The engine control unit is located in the electronics box, the left side, about the brake fluid reservoir or directly on the engine. The control unit determines the optimum ignition timing, injection timing and quantity of fuel injected. Thus there is a coordination of the work of the control unit with other vehicle systems, such as transmission control or anti-theft system.

The information from the other sensors and the control voltage is supplied to the executive bodies, provide optimum engine performance in any situation. If some of the sensors fail, the control unit switches to the emergency program in order to avoid possible damage to the engine and to drive further. In this case, the motor runs unevenly and with an increase in the gas tends to stop.

Structure and principle of operation

Location of individual elements of the engine management system on the example of some models shown in the illustration Details of installation of the control module front door.

On these models standard of manufacture 12.2000 used 6-pin (A-F) electronic control module (ECM) 2.0 IU. On models complete AMG, as well as on standard models of release with 12.2000 5-pin set (1-5) 2.8 IU module that is placed in an aluminum protective housing hermetically sealed.

Input signals ECM

As the input signals from the ECM uses the following information sensors / actuators:

• The coolant temperature sensor (ECT);
• Hot-film mass sensor of the intake air (MAF);
• Intake air temperature sensor (IAT), embedded in the assembly MAF;
• Throttle Position Sensor (TPS);
• Level sensor / temperature / quality motor oil;
• Control switch Tempostat / Speedtronic ^1);
• The pressure sensor in the fuel tank ^1);
• The pressure sensor in the intake manifold ^{1) 2);}
• AT Position Sensor (PNP), - a transmission control module (ETC);
• Differential crankshaft position sensor (CKP);
• Camshaft position sensor (CMP) Hall effect;
• Oxygen sensors (lambda probes);
• Knock sensors (KS);
• The sensor (potentiometer) throttle position.

¹⁾ The models for the US market

²⁾ a complete set of models AMG (2.8 IU to 6.00)

The output signals of ECM

By the weekend ECM commands include:

• Signals activation of ignition coils (one twin coil per cylinder);
• Signals activation of fuel injectors;
• The signals activate the throttle actuator;
• Signals activation of the fuel pump relay;
• Output signal component of the pulse-width modulation (PWM) transducer EGR (EGR);
• Signals activation of mixing air;
• Signals activation of the drive switching intake pipe;
• Signals activation of the starter relay;
• Signals activation of purge of a coal adsorber of system of catching of fuel evaporations (EVAP);
• Signals activation of the cut-off valve of a coal adsorber ^1);
• The signals of the data line fault memory.

¹⁾ The models for the US market

The information transmitted on the bus data exchange CAN

• Operating status transmission control system (ETC);
• Operating state of dynamic stability control systems (BAS / ASR / ESP / ETC), - the control unit;
• Operating state of the electronic gas pedal
• Information about the current state of the AT;
• Information overload protection transmission;
• Wheel speed (speed and acceleration);
• Status gauge-switch of stoplights;
• Status meters / indicators dash;
• Status of K / (on / off, pressure in the refrigerator path);
• Signals switching Tempostat / Speedtronic.

A brief description of the principles of functioning of some of the sensors / actuators control

Throttle Position Sensor (TPS) is mounted in the throttle actuator and outputs to the control module (ECM) information on the current angle of the throttle position. The second potentiometer informs ECM data base values and generates a signal when a backup failure of the throttle potentiometer.

The level sensor / temperature / quality motor oil sump is installed in the engine and generates three information signal pulse-width modulation (PWM), and transmitted to the ECM (CAN bus) on the instrument cluster of a vehicle.

The oil quality is determined on the basis of the data of the date of the last replacement.

The crankshaft position sensor (CKP) is screwed into the cylinder block at the flywheel. It transmits information to the control unit of the engine speed and TDC position of first cylinder.

Camshaft sensor (CMP) is located on the end of the cylinder head cover. He, along with the crankshaft position sensor sends information to the control unit of the TDC of first cylinder. It serves to synchronize the ignition timing and ignition sequence.

Throttle actuator comprises a motor and two potentiometers. The mechanism adjusts throttle position, ensuring the stability of the idle speed, regardless of the connection of additional power consumers, such as the power steering or the compressor K / V.

Gas pedal position sensor is the area of the driver's feet directly on the axis of the gas pedal. It tells the control unit information about the position of the pedal. For reasons of safety pedal sensor taken from an additional signal, as well as from the throttle potentiometer.

Coolant temperature (ECT) is located in the thermostat housing. It is a resistor with a negative temperature coefficient (NTC), the resistance of which decreases with increasing temperature.

The gauge of measurement of weight of air (MAF) is a Hot-meter mounted in the intake air path of the engine. Issued ECM sensor information is used to determine the parameters of dosage of air-fuel mixture.

Intake air temperature sensor (IAT), - NTC-resistor assembly built into MAF sensor.

The ventilation system of the fuel tank / fuel vapor capture (EVAP) consists of a coal adsorber and a purge control solenoid valve of the latter. The adsorber accumulated fuel vapors resulting from heating it. When the engine is accumulated in the adsorber fuel vapor are drawn into the inlet path and routed into the combustion chamber.

Lambda probes (lambda probes) measuring the oxygen content in the exhaust gases before and after the catalytic converter and transmitting appropriate signals to the engine control unit. One lambda sensor located in front of and one downstream of the catalytic converter.

Sensor (s) of detonation (KS) is screwed directly into the body of the cylinder and serves to prevent dangerous shock combustion of the fuel mixture, allowing installation to hold the ignition timing to the knocking limit, when the effective output of the engine is maintained at the maximum level with the minimum fuel consumption.

The system consists of mixing air installed in front of the power unit and the air pump operated synchronously with it combined valve switches pribolchennyh front to each of the cylinder heads.

Exhaust gas recirculation. Combined with an electronic EGR valve vacuum transducer mounted under the right cylinder bank. It is controlled by the PWM signal transducer, vyrabatyvaemy ECM. Mixing in the intake tract of the engine a certain amount of exhaust gases reduces emission into the atmosphere of nitrogen oxides (NO _X). Opening the valve is made with a depth of negative pressure 80 ÷ 220 mbar.