Integrated Injection-Ignition System - M.marelli-Weber I.a.w.-49F; System Operating Strategies; Introduction - Fiat 1998 Marea Service Manual

Marea-Marea
1998 range

INTEGRATED INJECTION-IGNITION SYSTEM - M.MARELLI-WEBER I.A.W.-49F

Introduction

The I.A.W.-49F 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.
System identification codes change according to the version:
- I.A.W.-49F.B6 for version with manual gearbox
- I.A.W.-49F.L3 for version with automatic transmission
This system therefore adopts a single ECU, 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.-49F system ensures efficient operation and optimisation of performance and fuel consump-
tion. Harmful emission levels are reduced through real time response to the various engine operating
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 TDC of cylinder 1;
3. intake air temperature;
4. throttle valve angular position;
5. coolant temperature;
6. 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).
11. presence of knock
This data, generally analogue, is converted into digital signals by analogue/digital (A/D) converters so
that it may be used by the ECU.
Note that this I.A.W.-49 injection-ignition sytem does not require adjustment because it is self-adjust-
ing 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 ECU. 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;
i 6. control relays.
Copyright Fiat Auto
Weekend®
16v
Engine
Fuel system
10.
1