When the battery is disconnected, the data is erased and to restore them, you must start the engine and keep it idling until the system adjusts. This process will be best done by doing a road test for 15 minutes at 2500-3500 rpm.
Elements of the Bosch L3.1 injection system (jetronic)
Low pressure intermittent Bosch L3.1 fuel injection system. Fuel is supplied by the fuel pump through the filter along the line to the injectors. A pressure regulator mounted at the outlet of the fuel line and connected to intake manifold vacuum maintains a constant pressure in the injectors, returning excess fuel to the fuel tank.
The pulse damper at the fuel line inlet reduces fuel pressure fluctuations.
Electronic control device (ECU) and an air flow meter are mounted on the air filter housing. The ECU uses signals from various sensors to determine the opening time of the injectors for any operating condition.
The electronic control device receives the following signals:
- the amount of air consumed by the engine and passing through the air flow meter;
- air temperature;
- engine speed and angular position of the crankshaft;
- throttle position.
The injectors work simultaneously, spraying fuel towards the intake valve.
An additional air duct provides additional air supply in cold start mode.
Elements of the Bosch LU2-Jetronic injection system
The principle of operation of the LU2-Jetronic system is similar to that described for the L3.1-Jetronic system (see above), but with the following differences:
- the throttle body has a single chamber;
- there is an oxygen sensor;
- there is a catalytic converter.
The most significant difference is that the LU2-Jetronic system has an oxygen sensor in the exhaust system, which allows the electronic control unit to perform mixture adjustment, which makes it possible to use a catalytic converter.
Elements of the Bosch Motronic MP3.1 injection system
The principle of operation of the Bosch Motronic MP3.1 system is similar to that described for the L3.1-Jetronic system (see above), but with the following differences:
- The ECU manages the ignition system in addition to the fuel injection system, creating an integrated engine management system;
- reduced ignition distribution system;
- instead of an air flow meter, an air temperature sensor and a manifold pressure sensor are used.
Elements of the Bosch Motronic M1.3 injection system
The principle of operation of the Motronic M1.3 system is similar to that described for the L3.1-Jetronic system (see above), but with the following differences:
- The ECU controls the ignition system and the fuel injection system, creating an integrated engine management system;
- the engine position/speed sensor is used to obtain information about the position of the crankshaft and the engine speed;
- The ECU controls the idle speed in all operating conditions through the idle speed control valve;
- an oxygen sensor is used to allow the ECU to control the fuel mixture very precisely, allowing the use of a catalytic converter;
- A knock sensor installed in the cylinder block is used to detect the onset of detonation or pre-ignition. This allows the ECU to select the optimum ignition timing for prevailing engine operating conditions without risk of engine damage.
Elements of the Bosch Motronlc ML4.1 injection system
The principle of operation of the Motronlc ML4.1 system is similar to that described for the L3.1-Jetronic system (see above), but with the following differences:
- ECU includes cold start function and fault memory;
- mixture bypass screw replaced with throttle position potentiometer;
- the throttle body has a double chamber;
- idle speed is maintained at a predetermined level (regardless of load) idle speed valve.
Elements of the Bosch Motronic MP5.1 injection system
Bosch Motronic MP5.1 engine management system (ignition / fuel injection system) includes a catalytic converter and an evaporative emission control system and meets the latest emission control standards.
The fuel pump, which is submerged in the fuel tank, supplies fuel through a filter mounted under the rear of the vehicle. The pressure in the fuel system is controlled by the fuel line pressure regulator.
The electrical control system consists of the ECU along with the following sensors:
- throttle position potentiometer;
- coolant temperature sensor;
- incoming air temperature sensor;
- lambda sensor - informs the ECU of the oxygen content in the exhaust gases;
- crankshaft position sensor;
- intake manifold pressure sensor;
- vehicle speed sensor.
The ECU controls the fuel injectors by changing the pulse width (length of time when the nozzles are open). The fuel mixture is constantly modified by the ECU to provide the optimum ratio for hot or cold starting, warm-up, idle and acceleration.
The ECU also senses idle speed through an air assist valve that bypasses the throttle.
An electric heating element is attached to the injector body, which prevents possible icing when starting a cold engine.
If there is an error in any of the data received from the sensor, the ECU enters standby mode. In this case, the ECU ignores the incorrect sensor signal and assumes a pre-programmed value that will allow the engine to continue running (albeit with less efficiency). If the ECU enters the backup mode, the alarm lamp on the instrument panel will light up and the fault will be recorded in the ECU memory. After that, it is necessary to carry out a full test of the engine management system using a special electronic diagnostic test stand, which is simply plugged into the diagnostic socket of the system.
Elements of the Magneti Marelli 8P injection system
Magneti Marelli 8P engine management system (ignition / fuel injection system) very similar in operation to the Bosch MP5.1 system (see above), except for the idle speed control system.
On the Magneti Marelli system, idle speed is controlled by the ECU via an auxiliary motor attached to the throttle body.
The engine has a pusher that controls the opening of an additional channel that bypasses the throttle. When the throttle is closed, the ECU controls the pushrod movement, which regulates the amount of air that passes through the throttle body passage and controls the idle speed. The bypass is also used for additional air supply when starting a cold engine.