SUBASSEMBLY GRAPHIC INDEX

2.0 16V JTD, 2.2 16V JTD

INTRODUCTION

The intake air is filtered and directed towards the exhaust gas turbocharger via the flow meter which measures the flow rate and the temperature of the turbocharger outlet air before reaching the engine and the compressed air is cooled by passing through the air/air heat exchanger (intercooler).

The engine air supply circuit also includes:

- the EGR (exhaust gas recirculation) circuit which makes it possible to introduce a certain quantity of exhaust gases, lacking in oxygen, into the intake manifold.

The metering is controlled by the NCM according to the engine temperature, load and speed.

Op. 1080C EXHAUST GAS RECIRCULATION SYSTEM (E.G.R.)

- the intake air heating circuit; this device is designed to increase the temperature of the exhaust gases increasing the temperature of the intake air in order to facilitate the regeneration of the FAP (particle filter).

This device is only activated during the FAP regeneration stage.

Op. 1080B EXHAUST EMISSION CONTROL SYSTEM

Diagram showing engine air supply circuit

A, Intake air

B, Pressurized air

C, Exhaust gas plus air

D, Intake air heating circuit

E, Exhaust gas recirculation circuit EGR

F, Vacuum air circuit

G, Burnt gases exhaust

VARIABLE SWIRL

Diagram showing device

DESCRIPTION

The variable swirl device is designed to guarantee optimum turbulence of the air in the combustion chamber during the intake stage, according to the engine operation, in order to produce the best compromise between performance and pollutant emissions.

OPERATION

As a result of its shape, the helical duct (H) creates a high degree of turbulence for the intake air flow and this movement, known as swirl, also persists in the combustion chamber.

The shape of the tangential duct (T), normally closed by a throttle shutter, provides the intake air flow with a mainly axial rather than rotary element.

Throttle valves

There are throttle valves on each intake duct and they are activated by a pilot actuator and in certain circumstances by a solenoid valve.

The opening of the throttle valves is permitted in the following conditions:

- engine speed above: 2100 rpm at 80°C; 2500 rpm at 0° C

- injected flow rate above 40 mg/cycle.

Advantages of variable swirl:

- decrease in the formation of carbon particles as a result of the improvement in combustion at low engine speeds;

- good compromise between performance and emissions because the helical ducts (H) plus the tangential ducts (T) allow optimum cylinder filling.

Diagram showing operation of variable swirl device

H, Helical inlet ducts

T, Tangential inlet ducts

SWIRL SOLENOID VALVE

The swirl solenoid valve (1264) operates the actuator and is located by the thermostat casing, on the engine flywheel side.

Description

The solenoid valve places the vacuum pump and the swirl pneumatic actuator in contact.

Operation

The operation of the solenoid valve is the RCO type (Cyclical Opening Ratio) and is managed by a specific map (NCM) dependent on the intake air pressure sensor signal.

The solenoid valve is subject to the following variables:

- atmospheric pressure;

- vacuum supplied by the vacuum pump;

The pressure supplied by the solenoid lies between atmospheric pressure and vacuum pump vacuum level.

The swirl actuator is closed when it is not pneumatically operated.

Intake air pressure sensor

The regulation of the supercharging pressure is gradual and it is managed by the NCM on the basis of an engine management strategy that varies according to the engine speed and load.

This adjustment is implemented according to the supercharging pressure.

The data for this pressure value is supplied by the intake air pressure sensor, located on the air/air heat exchanger (intercooler).

View of air pressure sensor fitting

VACUUM RESERVOIR

The vacuum reservoir, which has a capacity of 0.5 litres, is fitted in the engine compartment, near the brake servo.

The vacuum circuit includes three 0.55 mm jets.

DESCRIPTION

The vacuum reservoir makes it possible to maintain sufficient braking assistance if the following components are operated simultaneously:

- swirl valve.

- intake air heater valve.

- supercharging regulation piston pneumatic control actuator.

1, Connection to the vacuum pump

2, Vacuum outlet to the swirl valve

3, Vacuum outlet to the supercharging regulation piston pneumatic control actuator

CONNECTIONS FOR THE SOLENOID VALVES

The connections for the solenoid valves operating the devices should correspond to the descriptions below:

- turbo pressure regulation solenoid; white/grey pipe by the white mark on the solenoid valve.

- swirl solenoid valve. connections without provisions.

- EGR exhaust gas recirculation regulation valve. white/grey pipe by the white mark on the solenoid valve.

- EGR valve casing solenoid valve. white/grey by the white mark on the solenoid valve.

- intake air heater throttle valve solenoid valve: white/grey by the white mark on the solenoid valve.

- intake air heater valve: brown pipe by the brown capsule.

- EGR valve casing: black pipe by the black capsule.