Manufacturing features

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Ref.	Description	Grp.
4	EXHAUST PIPES AND SILENCERS	1076
5	EMISSION CONTROL SYSTEM	1080
6	ENGINE LUBRICATION	1084
7	ENGINE COOLING	1088

MANUFACTURING FEATURES

899

Four in-line cylinder engine, 8 valves, 899 c.c., one camshaft in crankcase, hydraulic tappets with rod and rocker arm controls and S.P.I. Weber-Marelli 06F integrated injection- ignition.

1108

Four in-line cylinder engine, 8 valves, 1108 c.c., overhead camshaft and S.P.I. Weber-Marelli 06F integrated injection- ignition.

Description

GENERAL FEATURES

This assembly consists of the engine and all the systems required for engine operation:

• fuel feed system
• air delivery system
• exhaust system with catalytic converter
• fuel fume re-circulation system

The operation of these system is optimised by means of an electronic system controlled by an ECU (electronic control unit).

INJECTION-IGNITION SYSTEM OPERATION

S.P.I. Weber-Marelli 06F is an electronic system with the following integrated functions:

• induced discharge digital electronic ignition and static distribution
• intermittent single injector electronic ignition (1 - 3 - 4 - 2).

Fuel is injected at low pressure (approximately 1 bar) by the injector located upstream with reference to the throttle at each engine TDC.

At idling speed, the ECU controls the following:

• the instant of ignition
• air intake thus ensuring the engine in running regularly regardless of the environment conditions or applied loads.

The control unit handles injection ensuring that the stoichiometric ratio (i.e. air/fuel ratio) is constantly optimal.

The system functions are, essentially, the following:

• system self-adjustment
• self- test
• EXAMINER recognition
• cold start control
• combustion - lambda sensor control
• release phase fuel cut-off
• fuel fume re-circulation
• maximum rpm limitation
• fuel feed - fuel pump control
• connection to climate control system (where relevant)
• cylinder position detection
• injection stroke regulation
• spark advance regulation
• idling speed control and management

INJECTION SYSTEM

The essential air-fuel mixing conditions for the correct operation of controlled ignition engines are:

• the air/fuel ratio must be appropriately "dosed" and kept as close as possible to the stoichiometric value to ensure fast combustion and avoid unnecessary fuel consumption
• the mix must be "homogenous" i.e. must consist of petrol fumes spread as finely and evenly as possible in the air.

For optimal dosing, the ECU processes electric signals transmitted from:

• the intake air flow meter with integrated temperature sensor, signalling the exact amount of intake air
• rev and DTC sensor which generates an alternating single phase signal indicating the engine revolution frequency and engine TDC
• the throttle position potentiometer indicating required accelerating conditions
• coolant temperature sensor
• the lambda sensor, defining the amount of oxygen contained in exhaust gas.

IGNITION SYSTEM

This is a static inductive discharge ignition system (i.e. without high voltage distributor) with power modules located inside the injection ECU.

The system consists of two dual output terminal coils connected to the spark plugs by means of cables (1-4 and 2-3).

A map, containing the sequence of optimal spark advance values (for cylinder in explosion stroke) that the engine can adopt according to:

• engine ratio
• absolute pressure in intake manifold .

In the following conditions:

• idle speed
• full load

the ECU uses two separate tables according to the rpm only.

The ECU corrects the spark advance mainly on the basis of the following information:

• engine coolant temperature
• throttle position.

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