Introduction - ENGINE

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Hardened and tempered steel

Heat treatment applied to special steels to improve their mechanical characteristics: it consists of hardening, followed by tempering to induce a significant increase in toughness of the material.

Tempering: consists of heating to a temperature of < 720°C, in order to attenuate the effects of the hardening without eliminating its effects.

The material thus returns to a condition as close as possible to a stable chemical-physical balance.

Hardening: this is obtained when the structure of the metal at high temperature is harder and stronger than when cold.

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CURRENT DEVELOPMENTS

These engines are fitted with ''Magneti Marelli Common Rail' high pressure electronic injection systems for fast diesel engines totally managed by a Multijet MJD 6JF electronic control unit.

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CONTROL AREA NETWORK (CAN)

The CAN communication network allows data transmission between the ECU and other car computers.

The advantages of this system are that it does not require a lot of wiring and the number of sensors is reduced (because the computers are interconnected by the data transmission system, data supplied by one sensor may be used by several devices simultaneously).

The CAN also makes the fault diagnosis system more effective, speeds up signal transmission and improves component electric/magnetic compatibility (relationship between the various electric and electronic circuits on the car and interaction between the car and its surroundings).

The circuit that connects the ECU to the other terminals is an integrated circuit referred to as a CAN interface. Its function is to convert messages received by via the data transmission system into appropriate form.

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PERFORMANCE

This engine is able to provide the following performance:

• maximum power 51 kW - 69 BHP EC at 4000 rpm;
• maximum torque 180 Nm EC at 1750 rpm.

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Condensation

This the reverse of evaporation, i.e. when a substance passes from the vapour state to the liquid state; it takes place by compression or cooling.

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DEVICES ADOPTED

These engines are fitted with the following emissions control devices:

• exhaust system with oxidising catalytic converter;
• E.G.R. exhaust gas recirculation system with heat exchanger;
• crankcase vapour/gas recirculation system.

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DUCTILE OR SPHEROIDAL CAST IRON

Cast iron is referred to as ductile or spheroidal when, due to the addition of cerium and magnesium, globules or spheres of carbon at the graphite stage are contained in a mainly ferrite matrix. All the mechanical and technological properties of the metal are improved so it can be forged, welded and machined.

Its applications are very wide, because - unlike normal cast iron - it offers appreciable strength and percentage lengthening values.

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STRUCTURE

The unit comprises the engine and all the systems required for its operation:

• fuel system;
• air turbocharging system;
• engine cooling system;
• exhaust system with catalytic converter;
• oil vapour recirculation system;
• E.G.R. exhaust gas recirculation system with heat exchanger;

The operation of these systems is optimized by an electronic control system governed by a control unit.

An understanding of the operating logic of the control unit gives an overall picture of the entire GROUP 10 system Characteristic of working principle 1060 DIESEL FUEL INJECTION.

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Evaporation

Also called vaporization, this is the passage of a body from the liquid state to the gaseous state.

It occurs at any temperature, but, when all other conditions are the same, all the more slowly the lower the temperature.

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CONSTRUCTION

Direct injection turbodiesel engine without precombustion chamber, 4 cylinders in line, 1248 c.c., four valves per cylinder with hydraulic tappets, two overhead camshafts with geared power transmission, supercharged with variable geometry turbocharger and intercooler, Magneti Marelli MJD 6JF Common Rail electronic fuel injection system.

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PWM PULSE WIDTH MODULATION

A fixed voltage with modulated amplitude frequency pulses generated by the ECU to operate the actuators. A PWM voltage consists of a series of single polarity square waves. The ECU varies wave duration in response to demand.

A, Off

B, On

C, Low resulting current

D, Medium resulting current

E, Maximum resulting current

PWM PULSE WIDTH MODULATION

A pulse width modulated current varies in proportion to the ratio between Wave and Space. The Wave-Space ratio is the relationship between periods when the power supply is on and periods when it is off. This ratio may be considered as a percentage, and this is the way the Duty Cycle is measured.

Sensor

This is a system which, stimulated by any form of energy, reacts by changing its state, hence one or more of its characteristics (resistivity, volume, temperature, etc.).

For example, a material which, immersed in a magnetic field, undergoes a change in its conductivity, is a sensor.

New-generation sensors are solid-state devices of microelectronic technology, which can read the environment and provide responses in the form of electrical signals for subsequent processing for final control actions.

They can measure forces, acceleration, pressures and temperatures of gases, liquids and solids, concentrations of gases such as nitric oxides, oxygen, etc.

Viscosity

Property of matter whereby the particles of a body meet 'resistance' in sliding in relation to each other.

The value of the resistance or internal friction depends on the nature of the body, large in solids, very small in viscous liquids and non-existent in gases.

In liquids, viscosity decreases rapidly as temperature increases.

Engine with 4 cylinders in line, 16 valves, 1368 cc, twin overhead camshaft with Bosch ME 7.3 H4 electronic injection-ignition.

POWER - 95 BHP EC at 5800 rpm

TORQUE - 13 kgm EC at 4500 rpm

CYLINDER ARRANGEMENT - 4 in line

BORE - 72 mm

STROKE - 84 mm

CYLINDER CAPACITY - 1368 cc

CYLINDER HEAD - aluminium

CRANKCASE - cast iron

CRANKSHAFT - in ductile cast iron with 8 counterweights and 5 main bearings with torsional damper

TIMING SYSTEM - two overhead camshafts with gear drive and play take-up from the intake shaft to the exhaust shaft, hydraulic tappets, 4 valves per cylinder

FUEL SYSTEM - returnless system with Bosch phased sequential injection

IGNITION - completely electronic with individual (pencil) coils

EMISSION CONTROL DEVICES - trivalent catalytic converter

LUBRICATION - forced via vane-type in-line gear pump.

COOLING: liquid with forced circulation via a centrifugal pump and sealed circuit; radiator and additional expansion tank.

Engine operation is ensured by the following systems:

• fuel supply system
• air supply system
• exhaust system with catalytic converter
• fuel vapour recirculation system
• engine cooling system.

The operation of these systems is optimized by an electronic control system governed by a control unit (see subunit 1056).

General view

1, Engine and power unit

2, Fuel tank and pipes

3, Pump(s) and fuel circuit devices

4, Engine air supply circuit

5, Petrol injection system

6, Exhaust pipes and silencers

7, Emission control system

8, Engine lubrication system

9, Engine cooling system

Fuel supply system

It is the returnless type with an electric fuel pump immersed in the tank and a casing which incorporates the voltage regulator, the fuel gauge and the filter (for further details see 1040).

Air supply system

Air supply system with plastic inlet manifold and large air filter casing to limit inlet noise (for further details see 1048 and 1072).

Exhaust system

The exhaust system is equipped with a system for post-treating exhaust gases with lambda sensors and a catalytic converter fitted in the engine bay (for further details see 1076).

Emission control system

The following emission control systems are fitted on this model:

• Exhaust emission control system with a three-way catalytic converter and one Lambda sensor upstream and one downstream of the catalyzer;
• crankcase vapour/gas recirculation system;
• fuel evaporation control system, (for further details see 1080).

Cooling system

Forced circulation with a centrifugal vane pump (for further details see 1088).