The use of an electronic engine management system has the following advantages:
- due to the optimal supply of fuel to the engine in all operating modes, fuel consumption is reduced while maintaining the dynamic characteristics of the car;
- due to more complete combustion of fuel, as well as the use of a catalyst, the emission of harmful substances along with exhaust gases is reduced;
- due to the fact that the electronic engine management system determines and stores faults in the memory, troubleshooting and detection of faults are greatly accelerated.
The control unit of the engine management system is a small, high-speed computer. The engine management system in all operating modes sets the optimal ignition timing, the moment and the amount of fuel supplied to the engine. Also, the engine management system interacts with other vehicle systems, in particular, with the automatic transmission control system or with the anti-theft system.
Engine management components are very reliable and virtually maintenance free. During maintenance, it is only necessary to replace the air filter and spark plugs. Since it is necessary to use complex expensive equipment to check, adjust and repair the engine control system, this work must be done at a service station.
It is not necessary to carry out the adjustment of the idling speed and the CO value as part of the preventive care / inspection of the vehicle.
Security note. The fuel system is under pressure. Depressurize the fuel system before disconnecting the fuel lines. To do this, cover the connection point with a rag and, being careful, disconnect. When disconnecting system components, fuel can splatter, so use goggles to protect your eyes from fuel getting into them.
To avoid personal injury and/or damage to devices and components of the engine control system (ignition and fuel injection systems), observe the following rules:
- when the engine is running, do not touch high-voltage wires and do not disconnect them;
- connect and disconnect the wires of the engine management system (injection and ignition), as well as wires of measuring instruments only when the ignition is off;
- people with cardiac stimulants are not recommended to check and repair the engine management system
- no fuel should be injected during the pressure test, for this follow the instructions in section «Pressure test».
Attention. When working on the fuel injection device, always observe the general rules for safety and hygiene, see chapter «Fuel system».
Operation of the engine management system
Fuel from the fuel tank is supplied by an electric fuel pump through a fuel filter located on the bottom of the vehicle to the fuel injectors. The fuel pressure regulator maintains a constant pressure in the fuel system.
Electronically controlled injectors inject fuel into intake ports just ahead of the engine's intake valves. The engine control unit controls the fuel injector by changing the pulse width, that is, the amount of time the injector is open, to provide a richer or leaner fuel mixture.
The air needed to burn the fuel passes through the air filter, air flow meter and throttle valve to the cylinder intake ports.
The volume of air entering the engine determines the amount of fuel that is needed for complete combustion of the fuel. The air flow meter is a tape conductor that is energized. The constant temperature of the tape is maintained by electric current, which varies depending on the mass of passing air. The current that must be supplied to maintain a constant temperature of the tape is proportional to the mass of the air flow. Based on information from the air flow meter and other sensors, the control unit regulates the time and amount of fuel injected according to the measured amount of air and the engine speed. The longer the injector is open, the more fuel is injected.
Information from various sensors (sensors) and commands given to the actuators ensure the optimal mode of operation of the engine in all operating modes. If important sensors fail, the control will switch to an emergency driving program to avoid engine damage and keep driving. The failure of the sensors will not necessarily be accompanied by a noticeable deterioration in engine performance, however, after a while, during the next exhaust gas check, it will be noted when polling the failure memory of the engine management system.
The throttle switch is located in the throttle assembly. The switch sends a signal to the control unit about the position of the throttle valve at idle. The control unit opens or closes the throttle valve via a servomotor and thus maintains a stable idle speed.
The coolant temperature and engine air temperature sensors report the current temperature value by means of their electrical resistance. As the temperature increases, the resistance of the sensor decreases.
The ventilation and vapor recovery system consists of an activated carbon filter and a solenoid valve. The activated carbon filter prevents the penetration of harmful fuel vapors from the fuel tank into the atmosphere. The fuel evaporating during heating is accumulated in a container with activated carbon. When the engine is running, fuel vapors are taken from the tank and sent to the engine for combustion.
The lambda sensor measures the oxygen content in the exhaust gas stream. The control unit, at its signal, maintains the content of harmful emissions in the exhaust gases at the lowest level. For vehicles with a catalyst, the composition of the exhaust gases is maintained at a level that provides the best afterburning in the catalyst.
The knock sensor is used to detect the onset of detonation in the engine cylinders and, based on this information, the engine control unit reduces the ignition timing. In the presence of ignition faults, the control unit shuts off the fuel supply to the corresponding cylinder.
Engines 1.8-I/125 hp and 2.4-/2.8-I-V6. Suction pipe of variable length, which, depending on the operating conditions of the engine, changes the length of the path of air entering the cylinders. For this, a pneumatic rotary damper is used. At low engine speeds, the air enters along a longer path and, due to the resonance effect, the engine cylinders are more completely filled, resulting in increased torque. At high speeds, the air path is shortened to better utilize the engine's power potential.
Engines 1.8-I/125 hp and 2.4-/2.8-I-V6. The device for turning the camshaft that controls the intake valves, depending on the engine speed, provides a change in the valve timing. When turning the camshaft to position «spat/delay», at idling speed, engine smoothness is improved; accordingly, at high speeds, engine power increases. At low and medium speeds, closing the intake valves earlier improves cylinder filling and thus improves torque characteristics.
Pic. 4B.1. Location of elements of the MOTRONIC engine management system in the engine compartment with a 1.8-I / 125 hp engine.
1 - air flow meter,
2 - coolant temperature sensor,
3 - camshaft position adjustment valve,
4 - throttle valve assembly,
5 - electrical connector lambda sensor,
6 - electrical connector of the crankshaft speed sensor,
7 - electrical connector knock sensor 2,
8 - electrical connector of the knock sensor 1,
9 - MOTRONIC engine control unit,
10 - valve for switching channels of the air supply system,
11 - temperature sensor of the air entering the engine,
12 - crankshaft speed sensor,
13 - knock sensor 2,
14 - knock sensor 1,
15 - fuel injectors,
16 - Hall sensor,
17 - ignition coils with switches,
18 - heated lambda sensor.
Pic. 4B.2. Location of elements of the MOTRONIC engine management system in the engine compartment with a 2.4-l engine
1 - electrical connector of the heated lambda sensor 1,
2 - electrical connector of the knock sensor,
3 - coolant temperature sensor,
4 - MOTRONIC engine control unit,
5 - temperature sensor of the air entering the engine,
6 - valve for switching channels of the air supply system,
7 - electrical connector heated lambda sensor 2,
8 - electrical connector of the crankshaft speed sensor,
9 - electrical connector of the knock sensor 2,
10 - MOTRONIC engine control unit,
11 - fuel pressure regulator,
12 - Hall sensor 2,
13 - lambda sensor,
14 - crankshaft speed sensor,
15 - knock sensor,
16 - valve 2 for switching channels of the air supply system,
17 - ignition coil with switch,
18 - knock sensor,
19 - fuel injectors,
20 - Hall sensor 1,
21 - lambda sensor 1,
22 - ground bus connection point,
23 - valve 1 for switching channels of the air supply system,
24 - air flow meter,
25 - Solenoid valve of the activated carbon tank.
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