Fiat 1995 Brava, Service Manual

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Bravo-Brava
M^ie,
Engine
Fuel system
10.
M.MARELLI-WEBER I.A.W.-1 AF.13 INTEGRATED INJECTION-IGNITION SYSTEM
Introduction
The I.A.W.-1 AF.13 system (I.A.W.-1 AF.23 for versions with automatic transmission) The Hitachi sys-
tem fitted to the 1581 i.e. 16v engine belongs to the category of digital electronic ignition systems with
static advance and timing, integrated with a phased, multipoint, intermittent electronic fuel injection
system.
This system therefore adopts a single E C U , single wiring system and a set of sensors common to both
systems.
Its function is therefore to inject an exact quantity of fuel into the engine intake duct upstream of the in-
take valves in order to obtain the correct mixture concentration.
The I.A.W.-1 AF.13 system ensures efficient operation and optimisation of performance and fuel con-
sumption. Harmful emission levels are reduced through real time response to the various engine operat-
ing conditions.
The system may be divided schematically into the following subsystems:
- Electric/electronic circuit
- Air intake circuit
- Fuel feed circuit
- Emission control devices
The system is able to monitor the following parameters by means of dedicated sensors:
1. instantaneous engine rpm;
2. position of each piston pair in relation to T D C of cylinder 1;
3. intake air temperature;
4. throttle valve angular position;
5. coolant temperature;
c. actual mixture concentration (by means of lambda probe signal);
7. intake manifold pressure;
8. vehicle speed;
9. battery voltage;
10. air conditioner compressor activation (if fitted).
This data, generally analogue, is converted into digital signals by analogue/digital ( A / D ) converters so
that it may be used by the E C U .
Note that this I.A.W.-IAF.13 injection-ignition sytem does not require adjustment because it is self-ad-
justing and self-adaptive.
SYSTEM OPERATING STRATEGIES
The management software resident in the ECU memory comprises a set of strategies. Each of these con-
trols a specific system control function.
Each strategy uses the various inputs listed above to process a set of parameters, using data maps saved
in specific areas of the E C U . The resulting data output is used to control system actuators, in other words
the devices used to operate the engine, namely:
1. injectors;
2. ignition coils;
3. solenoids of various types;
4. electric fuel pump;
5. engine idle speed actuator;
6. control relays.
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