System operating strategies

The I.A.W.-1AF.13 system (I.A.W.-1AF.23 for versions with automatic transmission) The Hitachi system 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 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 intake valves in order to obtain the correct mixture concentration.

The I.A.W.-1AF.13 system ensures efficient operation and optimisation of performance and fuel consumption. 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).

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.-IAF.13 injection-ignition sytem does not require adjustment because it is self-adjusting and self-adaptive.

SYSTEM OPERATING STRATEGIES

The management software resident in the ECU memory comprises a set of strategies. Each of these controls 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;
6. control relays.