2004 Alfa Romeo 156 engine

GETTING TO KNOW YOUR CAR
180
The heart of the VDC system is the VDC
control unit which with the data supplied by
the sensors installed on the car, calculates
the centrifugal forces generated when the
car is cornering. The yawing sensor detects
the rotations of the car around its own ver-
tical axis. The centrifugal forces generated
when the car is cornering are detected by
a highly sensitive lateral acceleration sensor.
The stabilising action of the VDC system is
based on calculations made by the
system’s electronic control unit which
processes the signals received from the
steering wheel rotation, lateral acceleration
and individual wheel rotation sensors. These
signals allow the control unit to recognise
the manoeuvre the driver intends to do
when turning the steering wheel.
The control unit processes the information
received from the sensors and is therefore
capable of detecting the position of the car
and comparing it with the trajectory the dri-
ver would like to follow instant by instant.
In the event of a discrepancy, the control
unit chooses and commands the most suit-
able action to bring the car back to the re-
quired course within a fraction of a second:
braking one or more wheels at a different
braking force and, if necessary it reduces the
power transmitted by the engine. The corrective actions are changed and con-
trolled continuously until the car returns to
the required course.
The action of the VDC system considerably
increases the active safety of the vehicle un-
der many critical situations and it is partic-
ularly useful also when the road surface grip
conditions change.
For the VDC, ASR and ABS
systems to work correctly,
the tyres must be of the same
brand and type on all wheels, in
perfect conditions and above all of
the specified type, brand and size.
WARNING
During use of the compact
spare wheel, the VDC sys-
tem continues working. It should be
borne in mind that the spare wheel
is smaller than a normal tyre,
therefore its grip is lower than that
of the other tyres of the car.
WARNING
VDC SYSTEM OPERATIONThe VDC system turns on automatically
when the car is started and cannot be
switched off. It is however possible to cut
off operation of the ASR system pressing the
corresponding button on the centre console.
The main components of the VDC system
are:
– an electronic control unit which
processes the signals received from the var-
ious sensors and brings about the most ap-
propriate strategy;
– a sensor that detects the position of the
steering wheel;
– four sensors that detect the rotation
speed of each wheel;
– a sensor that detects rotation of the car
around the vertical axis;
– a sensor that detects lateral acceleration
(centrifugal force).

GETTING TO KNOW YOUR CAR
181
ASR FUNCTION (ANTISLIP
REGULATION): GENERALThe ASR system integrates the VDC sys-
tem controlling the vehicle drive and com-
ing into operation automatically each time
one or both driving wheels skid.
Two different control systems are activated,
depending on the skidding conditions:
– If skidding concerns both driving wheels,
because it is caused by the excessive power
transmitted, the ASR system cuts in reduc-
ing the power transmitted by the engine.
– If skidding concerns only one driving
wheel, the ASR system cuts in automatically
braking the skidding wheel, with an effect
similar to that of a self-locking differential.The action of the ASR system is particularly
helpful under the following conditions:
– Skidding of the inner wheel on a bend,
due to the effect of the dynamic changes of
the load or over-accelerating.
– Excessive power transmitted to the
wheels, also in relation to the conditions of
the road surface.
– Acceleration on slippery, snowy or icy
surfaces.
– In the case of loss of grip on a wet sur-
face (aquaplaning).
CUTTING IN OF THE VDC
SYSTEMThe cutting in of the VDC system is indi-
cated by the flashing of the warning lightá
on the instrument cluster, to inform the
driver that the car is in critical conditions of
stability and grip.
TURNING ON THE ASR
FUNCTIONThe ASR function turns on automatically
each time the engine is started.
When travelling it is possible to switch the
system off and on again pressing the switch
(A-fig. 171
) on the centre console.
Function disconnection is shown by the led
on the ASR button being turned on. If the
function is turned off while travelling, it will
turn on again automatically the next time
the engine is started.
WARNING When driving on snow, with
snow chains fitted, if may be helpful to switch
off the ASR function: in these conditions in
fact, skidding of the driving wheels when
moving off helps to obtain better traction.
fig. 171
A0B0557m

GETTING TO KNOW YOUR CAR
182
EOBD SYSTEMThe EOBD (European On Board Diagnosis)
system fitted in the car conforms with the
98/69/EC (EURO 3) Directive and the
2001/1/EC Directive, level B (EURO4) for
2.0 JTS, 2.0 JTS Selespeed and JTD 20V
Multijet versions.
This system continuously monitors the
components of the vehicle related to emis-
sions; it also indicates, when the warning
light
U
comes on on the instrument panel
(together with the message + symbol
shown by the display) that the components
in question are in poor conditions.
The objective is the following:
– to keep under control the efficiency of
the system;
– to indicate when a malfunction causes
an increase in the emissions beyond the
threshold established by European regula-
tions;
– to indicate the need to replace the de-
teriorated components.
The system also has a diagnostic connec-
tor, which can be interfaced with adequate in-
struments, that enables the error codes stored
in the control unit to be read, together with
a series of specific parameters concerning the
operation and diagnosis of the engine.This check can also be made by the traf-
fic control agents.
If, when the ignition key
is turned to MAR, the
U
warning light does not
come on or if, when driving, it
lights up and emits a fixed light or
a flashing one (together with the
message + symbol shown by the
display), contact an Alfa Romeo
Authorized Service Station as soon
as possible. The operation of the
U
warning light can also be
checked by means of special equip-
ment available to the traffic con-
trol officers. Comply with the reg-
ulations in force in country where
you drive your car.
WARNINGAfter the problem has beel
resolved, to completely check the system,
the Alfa Romeo Authorized Services must
carry out tests on a test bench and, if nec-
essary, road tests that could be long.
WARNING LIGHT ON
INSTRUMENT PANELWhen the ignition key is turned to MAR,
the dial warning light
á
comes on but must
go out after a few seconds.
If the warning light does not go out, or if it
stays on (together with the message + sym-
bol on the display and the coming on of the
ASR button led) when the vehicle is running,
contact Alfa Romeo Authorized Services.
The flashing of the warning lamp when the
vehicle is running indicates the actuation of
the VDC system.
VDC system failure warning
In the event of a failure the VDC system
disengages automatically and the
á
warn-
ing light on the instrument cluster turns on
glowing steadily (together with the message
+ symbol shown on the display and the com-
ing on of the ASR button led).
In the event of a VDC system failure the
car behaves like a vehicle not fitted with this
system: in any case it is advisable to con-
tact Alfa Romeo Authorized Services as soon
as possible.

GETTING TO KNOW YOUR CAR
185
REFUELLING PETROL ENGINESIn order to prevent the vehicle being filled
with leaded petrol, the diameter of the filler
neck is smaller than the nozzle used on
pumps delivering leaded petrol.At low temperatures, the degree of fluid-
ity of fuel oil may become insufficient due
to the formation of paraffins leading to dan-
ger of clogging the fuel oil filter.
Therefore, to avoid inconveniences, sum-
mer and winter fuel oils are normally dis-
tributed depending on the season.
However, during the intermediate season,
characterised by a large difference between
outside temperatures (0°C to 15°C), the
quality of the fuel oil distributed to the
pumps may not be adequate.
In this case, and above all if the use of the
car involves stopping and then starting again
at low temperatures (e.g. mountains),
make sure the car is filled with winter fuel
oil; if not, you are advised to mix the fuel
oil with a DIESEL MIXadditive in the pro-
portions stated on the can, pouring first the
antifreeze and then the fuel oil into the tank.
TheDIESEL MIXantifreeze should be
mixed with the fuel oil before reactions due
to cold take place. Adding it too late will
prove pointless. The anti-pollution devices
present on the vehicle im-
pose the use of four-star
unleaded fuel with an octane num-
ber (R.O.N.) above 95.
Under no circumstances
should conventional leaded
petrol be used, as this
would irreparably damage the cat-
alyst. If the tank is accidentally
filled with leaded fuel, even in
minute quantities, DO NOT START
THE ENGINE. Do not attempt to di-
lute the petrol with lead free fuel.
Drain the entire fuel circuit and
tank.
If the catalyst is not
working properly, harmful
emissions reach the ex-
haust, resulting in environment pol-
lution.The car must be refuelled
only with fuel oil for motor
vehicles, in conformity with
European specification EN590. The
use of other products or mixtures
may damage the engine irrepara-
bly, resulting in invalidation of the
warranty for the damage caused.
If the tank is accidentally filled
with another type of fuel, do not
start the engine but drain the tank.
If the engine has been run even for
a brief period, the tank must be
drained together with the entire
fuel circuit.
JTD ENGINES

GETTING TO KNOW YOUR CAR
186
FUEL CAP
(fig. 176)
The fuel flap is released from inside the
car, raising the front part of the lever (A).
The fuel cap (A-fig. 177) has a catch
to prevent misplacing it (B) that fastens it
to the flap (C).
WARNINGThe fuel tank is sealed her-
metically and pressure may build up inside.
Any noise of rushing air when the cap is re-
moved is perfectly normal.
fig. 176
A0B0044m
fig. 177
A0B0045m
In case of need, replace
the fuel cap only with an
original one; otherwise,
the efficiency of the petrol vapour
recovery system could be badly af-
fected.
EMERGENCY FLAP OPENING
DEVICEIf the lever (A-fig. 176) fails to work,
it is still possible to open the flap by pulling
the cord (A-fig. 178) on the right-hand
side of the luggage compartment.fig. 178
A0B0388m
WARNINGFor your safety, make sure
that the fuelling pump nozzle is inserted cor-
rectly into the housing, before starting the
engine.
Do not get near the fuel
filler with naked flames or
lit cigarettes: danger of fire. Also
avoid going too near the filler with
the face to avoid inhaling harmful
vapours.
WARNING

GETTING TO KNOW YOUR CAR
188
EMISSION REDUCING DEVICES
(petrol engines)Trivalent catalytic converter
(catalytic silencer)
The exhaust system is fitted with a cat-
alyzer formed of alloys of noble metals. It
is housed in a stainless steel container which
is able to resist the high operating temper-
atures.
The catalyzer converts the unburnt hydro-
carbons, carbon monoxide and nitrogen ox-
ides present in the exhaust gas (even if in
small quantities thanks to the electronic in-
jection and ignition system) into harmless
compounds.Lambda probe
A sensor (lambda probe) measures the
content of oxygen present in the exhaust
gas. The signal transmitted by the lambda
probe is use by the injection and ignition
electronic control unit to adjust the air-fuel
mixture.
Anti-evaporation system
As it is impossible, even when the engine
is switched off, to prevent the formation of
fuel vapours, a system has been devised
which imprisons the vapours in a special ac-
tivated carbon container.
During operation of the engine, these
vapours are sucked up and sent to com-
bustion.
EMISSION REDUCING DEVICES
(JTD engines )Oxidising catalytic converter
Converts the polluting substances present
in the exhaust gases (carbon monoxide, un-
burned hydrocarbons and particulate) into
harmless substances, thus reducing the
fumes and smell that are typical of diesel
engines.
The catalytic converter consists of a stain-
less steel case that houses a ceramic hon-
eycomb body coated with noble metal used
as a catalyst.
Exhaust gas recirculation system
(E.G.R.)
This system recycles, i.e. re-uses, a vary-
ing percentage of the exhaust gases, de-
pending on engine operating conditions.
It is used, when necessary, to control ni-
tric oxides.
Due to the high tempera-
tures reached during oper-
ation of the catalytic converter, the
vehicle should not be parked over
inflammable materials (paper, fuel
oils, grass, dry leaves, etc.).
WARNING

CORRECT USE OF THE CAR
189
PROCEDURE FOR PETROL
ENGINESWARNINGIt is important not to press
the accelerator until the engine has started.
1) Make sure the handbrake is engaged.
2)Move the gear lever to neutral.
3)Fully depress the clutch pedal so that
the starter motor is not forced to crank the
toothed wheels of the gearbox.
4)Ensure that the systems and electrical
devices, especially if they absorb high quan-
tities of energy (e.g. heated rear wind-
screen) are switched off.
5)Turn the ignition to the AV Vposition
and release it as soon as the engine starts.
6)If the engine does not start, return the
key to the STOPposition and repeat the
operation.
WARNINGIf it is difficult to start the en-
gine do not insist with extended attempts
which may damage the catalyzer but con-
tact Alfa Romeo Authorized Services. The ignition switch is fitted with a safety
device which obliges the driver to return the
ignition key to the STOPposition before re-
peating the starting operation if the engine
does not start immediately.
Similarly, when the engine is running, the
device prevents the key being moved from
the MARto the AV Vposition.
STARTING
THE ENGINEWARNINGThe car is fitted with an elec-
tronic engine lock device. If the engine fails
to start see “Alfa Romeo CODE system”.
C C
O O
R R
R R
E E
C C
T T

U U
S S
E E

O O
F F

T T
H H
E E

C C
A A
R R
In addition to the notes
and specifications given be-
low we recommend that,
during the initial period, you do not
drive to full vehicle performance
(for example excessive accelera-
tion, long journeys at top speed,
hard braking, etc.).
To avoid useless con-
sumption of power and
possible draining the bat-
tery, never leave the ignition key
in the MAR position when the en-
gine is not running.
Running the engine in con-
fined areas is extremely
dangerous. The engine consumes
oxygen and produces carbon
monoxide which is a highly toxic
and lethal gas.
WARNING

CORRECT USE OF THE CAR
190
WARNINGOn the 2.0 JTS version,
keep the brake pedal pressed when starting
the engine. As the brake pedal stiffens if it
is pressed repeatedly with the engine off. In
this situation, to allow the engine to be
started, it is necessary to increase the pres-
sure exerted on the pedal itself.PROCEDURE FOR JTD VERSIONS1)Make sure the handbrake is engaged.
2)Move the gearshift lever to neutral.
3)Turn the ignition key to the MARpo-
sition. The warning light
m
on the instru-
ment cluster will turn on.
4)Wait for the
m
warning light to go
off, which will depend on how warm the en-
gine is. With the engine very hot the warn-
ing light may stay on for such a short time
that it is not noticed.
5)Fully depress the clutch pedal.
6)Turn the ignition key to AV Vas soon
as the
m
warning light goes off. Waiting
too long would make the glow plug heating
work pointless.WARNINGThe electric devices that ab-
sorb much energy (air conditioner,
rearscreen heating, etc.) are disengaged au-
tomatically during engine starting.
If the engine does not start at the first at-
tempt, move the ignition key back to the
STOPposition before repeating starting.
If starting is difficult (with the Alfa Romeo
CODE system efficient), do not insist with
prolonged attempts.
Only use an auxiliary battery if it is noted
that the cause is due to low charge of the
car’s battery. Never use a battery charger to
start the engine (see “If the battery is flat”
in the chapter “In an emergency”).
WARMING THE ENGINE– Drive off slowly, at medium revs with-
out accelerating abruptly.
– Do not drive at full performance for the
initial kilometers of the journey, Wait until
the engine coolant temperature is between
50 and 60°C.SWITCHING OFF– Release the accelerator pedal and wait
until the engine reaches idle speed.
– Turn the ignition key to the STOPpo-
sition and switch off the engine.
WARNINGAfter a taxing drive it is bet-
ter to allow the engine to “catch its breath”
before turning it off by letting it idle to al-
low the temperature in the engine com-
partment to fall.