Fuel is sucked in from the fuel tank by an electric pump and fed through the fuel filter to the fuel distribution pipe, and from there to the injectors. The pressure regulator maintains the pressure in the fuel system at 2.0±0.2 bar (ML4.1 and M1.5). An electrically controlled injector injects fuel into the intake manifold ahead of the intake valve.
Diagram of the Motronic 16-valve engine
1 - fuel tank
2 - fuel pump
3 - fuel filter
4 - fuel pressure regulator
5 - ignition coil
6 - air volume meter (for an 8-valve engine - an air flow meter)
7 - nozzle
8 - ignition distributor
9 - throttle position sensor
10 - computer
11 - idle speed regulator
12 - coolant temperature sensor
13 - knock sensor (16 valve engine only)
14 - crankshaft position and speed sensor
15 - catalyst
16 - lambda probe
17 - activated carbon filter
Air is sucked in by the engine through the air filter, and its volume is measured by a special sensor. There is a special damper in the sensor housing, which is deflected and held in this position under the pressure of the air flow. The deflection angle of the damper allows you to judge the volume of air entering the engine. Information from the sensor associated with the damper is transmitted to the computer. The computer, based on information about the volume of air and the number of revolutions of the engine, determines the moment of injection and the amount of injected fuel. With a longer opening of the nozzle, the amount of incoming fuel increases.
In the Motronic ML4.1 system, the throttle position sensor is located on the throttle shaft. It controls the fuel supply. As long as the idle switch contact is closed and the speed is above a certain value, the fuel supply to the engine is turned off by the computer. In the Motronic M1.5 system, information about the throttle position is transmitted to the computer by a sensor with a potentiometer.
The fuel pump relay is located in the engine block behind the left shock strut. It controls the fuel pump. The switch interrupts the current supply as soon as the ignition pulses stop (e.g. if the engine has stalled).
The crankshaft position and speed sensor is located on the side of the cylinder block. It transmits information about the number of revolutions of the crankshaft to the computer.
Lambda probe (oxygen sensor) measures the residual oxygen content in the exhaust gases in the catalytic converter exhaust system and transmits this information to the computer. In accordance with this, the computer changes the ratio "fuel/air" in a combustible mixture to obtain the desired composition of exhaust gases for the most efficient operation of the catalyst.
The idle air control regulates the amount of air at idle by acting on the throttle. Thanks to its operation, a stable idle speed is achieved, regardless of whether additional loads such as power steering or air conditioning are on or off.
The injection computer is located in the leg area on the right behind the plastic cover.
Motronic M2.5 16-valve engine
In this system, the air volume sensor works on a different principle. This sensor has the following advantages: small size, automatic compensation for the influence of ambient temperature and altitude, no moving parts and therefore little wear. The main element of such a sensor is an electric spiral blown by an air stream. To maintain a constant coil temperature, the amount of current needed to heat it varies according to the change in air flow. Current fluctuations are signals for the computer about the load of the engine. In accordance with this, the amount of injected fuel is regulated.
Fuel injection occurs sequentially, i.e. The injectors inject fuel according to the firing order of the cylinders. The optimal ratio of engine power and exhaust gas toxicity is achieved by determining the injection start time in relation to the opening of the intake valves.
The injection system has a knock sensor, with which the ignition timing is set as early as possible (at the edge of detonation). The computer also takes into account the octane rating of the fuel used. The presence of a knock sensor allows you to increase the compression ratio (compression) in the engine cylinders. Thus, the energy of fuel combustion can be used to the maximum, which, in turn, leads to its economy. The knock sensor is mounted on the cylinder block and connected to the computer by wires. In the event of a sensor failure, the computer automatically advances the ignition timing to an earlier one, which eliminates the possibility of engine damage due to detonation. True, this leads to a decrease in engine power.
The fuel pressure in the injection system is about 3.0 bar.
Motronic M2.7 in 2.0L turbocharged engines
The Motronic M2.7 system for Opel Calibra vehicles with a 2.0 liter turbocharged engine is a further development of the Motronic M2.5 system and is designed for more severe operating conditions.
In this system, instead of a throttle position sensor, a potentiometer is used, mounted on its axis. With its help, an accurate determination of the position of the damper is ensured.
To determine the temperature of the intake air, a temperature sensor is mounted in the pipe where the throttle valve is installed.
The turbocharger pressure is controlled by the computer through the turbocharger solenoid valve. There is a built-in sensor to measure the pressure in the valve. In addition, two switches are installed in the gearbox, also connected to the injection computer. When engaged in 1st gear or reverse, they give a signal to the computer, which reduces the boost pressure and thereby reduces the torque.
Attention! Whenever working on the injection system, extreme cleanliness must be observed. Before disassembling the system, it is necessary to flush its elements.
Attention! The system is under pressure. When replacing any of its elements, the pressure must be relieved. To do this, carefully loosen the fastenings of the pipeline between the fuel pump and the filter. If the pipeline is disconnected, close its end with a suitable plug. The pressure drops by itself (without disconnecting the pipeline), if the engine has not been running for several hours.
Visitor comments