Contents (page 2 of 2)

The BOSCH 1.5.5 system fitted on the 1242 16v ie engine belongs to the category of static advance, digital, electronic ignition systems integrated with phased, intermittent type electronic fuel injection systems.

The integrated system can be divided into the following sub systems:

ELECTRICAL/ELECTRONIC CIRCUIT
AIR INTAKE CIRCUIT
FUEL SUPPLY CIRCUIT
EMISSION CONTROL DEVICES

The system is capable of detecting the following parameters by means of appropriate sensors:

• - the engine rotation speed;
• - the correct sequence of TDC in the explosion stroke for the cylinders (injection timing);
• - the absolute pressure in the inlet manifold;
• - the intake air temperature;
• - the position and the variation speed of the accelerator butterfly;
• - the temperature of the engine coolant;
• - the possible presence of detonation;
• - the speed of the vehicle;
• - the battery voltage;
• - the possible engagement of the air conditioning;
• - the possible end of travel of the power assisted steering.

This information, usually in analogue format, is converted into digital signals by analogue/digital (A/D) converters so that they can be used by the control unit.

The management programme (software) is stored in the control unit memory and consists of a series of strategies, each of which manages a precisely defined system control function.

Through the use of the information (input) listed earlier, each strategy processes a series of parameters using data maps stored in special areas of the control unit memory and then operates the system actuators (output), which consist of devices which allow the engine to operate, such as:

• - injectors;
• - ignition coil;
• - relay feeds;
• - implementation solenoid valves;
• - interface with the vehicle (diagnostic warning light, diagnostic instrument, etc.).

NOTE The BOSCH 1.5.5 injection/ignition system does not require any adjustment as it is the self-adjusting type.

NOTE In the drawings and diagrams, the numbers indicate the corresponding engine control unit pins (number/A for connector A, number/B for connector B).