Multec single point fuel injection system
The fuel injection device has a throttle valve, an idle speed control motor, a throttle position sensor, fuel injectors and a pressure regulator.
The duration of the electric pulse supplied to the fuel injector determines the amount of injected fuel and is processed in the Multec electronic control unit (ECU) based on information received from various sensors.
This includes the throttle position sensor. manifold pressure sensor, distributor (in engines 1.4 and 1.6 l gives information about the position / speed of rotation of the crankshaft), crankshaft position/speed sensor (only 1.8L engine), coolant temperature sensor and exhaust gas oxygen sensor.
The idle speed is controlled by an electric motor that regulates the amount of air passing through the throttle. The electric motor is controlled by an electronic control unit. The model is equipped with a catalytic converter.
Multec multipoint fuel injection system
This system is under the overall control of the engine management system (chapter 5).
Fuel is supplied from the tank through a filter and pressure regulator to the fuel distributor (excess fuel is returned to the tank), which plays the role of a reservoir for all four fuel injectors working in pairs (for cylinders NN 1 and 2 at the same time, as for cylinders NN 3 and 4).
The duration of the electric pulses going to the fuel injectors determines the amount of fuel supplied and is processed by the Multec device (ECU) based on information from various sensors.
The system components are shown in Figure 4.47.
Bosch Motronic fuel injection system
There are two variants of such a system. The Motronic M1.5.2 system is used on engines with one camshaft, Motronic M2.5 on engines with two such shafts.
On engines with M1.5.2, the injectors receive 1 electrical impulse / 1 revolution of the crankshaft, which activates all four injectors simultaneously. Dual cam engines use sequential fuel injection, so each injector receives a separate electrical pulse, allowing more precise control of fuel delivery to each cylinder.
On engines with a single camshaft, the flow of incoming air is carried out by a hot-film anemometer. The same system is installed on engines with two camshafts.
The models are fitted with a catalytic converter. All engines run on unleaded gasoline. Leaded gasoline must not be used.
Components of the fuel injection system - check
Except for testing electrical systems (chapter 12) and ignition systems (chapter 5), the individual components of the injection system are difficult to test under normal conditions.
In the event of a breakdown, most often, the electronic engine control unit allows it to work (using a data collection program), although with less efficiency and reduced controllability. Fault codes can be deciphered using special Vauxhall / Opel equipment.
If a defect appears (indicated on the instrument panel) and the cause cannot be determined immediately, a check should be carried out as indicated below.
Check that the spark plugs are in good condition and have the correct gap, that the crankcase ventilation hoses are not clogged or damaged, and that the throttle cable is adjusted.
If the engine is running hard, check the compression (chapter 2) and note that one of the valve lifters may be damaged.
If a clogged fuel injector is suspected, try a proprietary cleaner (which is usually added to the fuel tank) manufacturer's instructions.
If the defect persists, check the ignition system components as indicated in chapter 5.
If necessary, check the entire system in sequence, checking all fuses, wiring, vacuum hoses, for damage, dirt, leaks, and other defects.
After checking the parts of the system for defects, send the vehicle to Vauxhall/Opel car service specialists for inspection on special diagnostic equipment.
Do not check any parts, especially the electronic control unit, without the use of appropriate equipment, as this can lead to costly component failure.
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