Fiat 1998 Marea Weekend, Service Manual

Page: 271 / 846

Marea- Marea Weekend 0
Engine
99 update
Fuel system
10.
HITACHI INTEGRATED INJECTION/IGNITION SYSTEM
INTRODUCTION
The Hitachi system fitted on the Marea-Marea Weekend versions with the 1747 i.e. 16v engine belongs to
the category of static advance, digital electronic ignitino systems integrated with phased, multiple, inter-
mittent type electronic fuel injection systems.
The 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 via special sensors:
1. the engine rotation speed;
2. the position of each pair of cylinders in relation to TDC for cylinder 1;
3. the engine intake air flow rate;
4. the position and variation speed of the position of the accelerator butterfly;
5. the temperature of the engine coolant;
6. the effecive mixture strength (through the Lambda sensor signal);
7. the possible presence of detonation;
8. the speed of the vehicle;
9. the battery voltage;
10. whether or not the climate control compressor is switched on.
This information, usually in analogue format, is converted into digital signals by the analogue/digital con-
verters (A/D) for use by the control unit.
In particular, any engine operating point is identified by two parameters:
- the engine rotation speed, measured in revs per minute (rpm);
- the engine load, which consists of the quantity of air drawn in by each cylinder.
- This quantity is calculated on the basis of the intake air flow rate and is represented by the parameter
TP, measured in milliseconds (ms).
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.
By using the information (input) listed previously, each strategy processes a series of parameters, using
the data maps stored in special areas of the control unit memory, and then controls the system actuators
(output), which are the devices which allow the engine to operate, namely:
1. injectors;
2. ignition coils;
3. various type solenoid valves;
4. fuel pump;
5. relays.
NOTE The HITACHI injection/ignition system does not require any adjustments as it is the self-adjusting
and self-adapting type.
NOTE The numbers in the boxes in the drawings and the wiring diagrams denote the corresponding HI-
TACHI engine management control unit pins (a number followed by A, indicates connector A, a
number followed by B, indicates connector B).
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