Bosch M1.5.5 Integrated Injection/Ignition System - Fiat 1998 Marea Service Manual

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BOSCH M1.5.5 INTEGRATED INJECTION/IGNITION SYSTEM

Introduction
The BOSCH M1.5.5 system fitted on the 1242 16v engine belongs to the category of static advance digi-
tal electronic ignition systems integrated with phased multiple intermittent type electronic fuel injection
systems.
The integrated system can be summarized in 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 suitable sensors:
- the engine rotation speed;
- the correct sequence of TDC for the explosion stroke in the cylinders (injection timing);
- the absolute pressure in the inlet manifold;
- the temperature of the intake air;
- the position and the variation speed of the accelerator butterfly position;
- the temperature of the engine coolant;
- the possible presence of detonation;
- the speed of the vehicle;
- the battery voltage;
- whether the air conditioning is switched on;
- whether the power steering is in the end of travel position;
This information, usually in analogue format, is converted into digital signals by analogue/digital convert-
ers (A/D) in order to be able to be used by the control unit.
The control unit memory contains the management programme (software) which consists of a series of
strategies, each of which manages a precise system control function.
Using the information (input) listed previously, each strategy processes a series of parameters using data
maps stored in special areas of the control unit memory and then controls the system actuators (output)
which consist of devices which allow the engine to operate, namely:
injectors;
relay feeds;
implementation fan;
interface with the vehicle (diagnostic warning light, diagnostic instrument, etc.).
NOTE The BOSCH M1.5.5 injection/ignition system does not require any adjustments as it is the self-
regulating type.
NOTE The numbers in the drawings and the diagrams indicate the corresponding pins for the engine
control unit (number/A for connector A, number/B for connector B).
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