Fiat 1996 Brava Service Manual page 413

Bravo-Brava )§l i» Engine
'98 range Fuel system
10.
M.MARELLI-WEBER I.A.W.-49F INTEGRATED FUEL INJECTION-IGNITION
Introduction
The I.A..W.-49F system fitted to the 1581 i.e. 16v engine belongs to the group of digital electronic igni­
tion systems with static advance and static timing, integrated with an electronic fuel injection system of
the intermittent multiple synchronized type.
The identification codes of the system are as follows, depending on the version:
- I.A.W.-49F.B4 for version with manual gearbox
- I.A.W.-49F.L2 for version with automatic transmission.
This system thus has only one control unit, a single set of wiring and a set of sensors common to both
systems.
Its function is to inject into the engine's inlet port, upstream of the inlet valves, an exact quantity of
petrol to be mixed with the air introduced into the cylinder, so as to obtain a correct mixture strength.
The I.A.W.-49F system ensures efficient operation thus optimizing performance and consumption, and
reducing harmful emissions, by providing a response in real time to the engine's different operating con­
ditions.
The system can be divided into the following sub-systems:
- Electrical/electronic system
- Air intake system
- Fuel supply system
- Emission control systems
Via suitable sensors, the system can measure the following parameters:
1. instantaneous engine rpm;
2. the position of each pair of pistons in relation to TDC of cylinder 1;
3. air intake temperature;
4. angular position of the throttle valve;
5. engine coolant temperature;
6. actual mixture strength (via the Lambda probe);
7. pressure in the inlet manifold;
8. vehicle speed;
9. battery voltage;
10. when the air conditioner (if present) is switched on;
11. the presence of any knocking.
This information, generally analogue, is converted into digital signals by the analogue/digital converters
(A/D) in order to be used by the control unit.
Finally, it is important to note that the I.A.W.-49F fuel injection-ignition does not require any adjust­
ment as it is self-adjusting and self-adapting.
SYSTEM MANAGEMENT STRATEGIES
The management program (software) resides in the control unit's memory; it consists of a series of
strategies, each of which manages a precise control function of the system.
By using the information (inputs) listed above, each strategy works out a series of parameters, based on
the data maps stored in appropriate areas of the control unit's memory, and then drives the system's ac­
tuators (outputs), the devices which enable the engine to operate, namely:
1. fuel injectors;
2. ignition coils;
3. various types of solenoids;
4. electric fuel pump;
5. engine idle speed actuator;
6. control relays.
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