Fiat 1998 Marea Weekend, Service Manual

Page: 159 / 846

Marea-Marea Weekend®
1998 range
16v
Engine
Fuel system
10.
COMPONENTS OF INJECTION-IGNITION SYSTEM
The injection-ignition system consists mainly of wiring, an electronic control unit (ECU) and the fol-
lowing sensors and actuators:
Sensors
- Rpm and TDC sensor
- Knock sensor
- Throttle position sensor
- Coolant temperature sensor
- Intake air temperature and pressure sensor
- Vehicle speed sensor
- Lambda probe
Actuators
- Engine idle speed actuator
- Electric fuel pump
- Fuel vapour cut-off valve
- Injectors
- Ignition coils
INJECTION-IGNITION SYSTEM WIRING
The various system components are connected by a single wiring system fitted with connectors of vari-
ous types. These are grouped in special ducts fitted to the engine (prewiring).
INJECTION-IGNITION ECU
The injection - ignition system control unit adopted is specific to this version. It is connected to the elec-
trical wiring by two connectors. These are 52 pin (upper connector) and 28 pin (lower connector) re-
spectively.
This digital, microprocessor unit features high computing capacity and is accurate, reliable and versatile.
It consumes little energy and is maintenance-free.
The ECU's task is to process signals from the various sensors through the application of software algo-
rithms and control the actuators in order to achieve optimal engine performance.
Essential features of the electronic control unit are as follows:
- Data acquisition and coding section
- Microprocessor
- ROM memory
- RAM memory
- EEPROM memory
- Drivers
a. Data acquisition and coding section
This consists of a set of electronic components (A/D converters) designed to receive data in the form of
analogue electrical signals. Inside, the signals are converted into digital signals, processed and stored.
Copyright Fiat Auto
2 5