Technical data
i
FUEL
SYStEM
8’
,The
purpose!
of’
the
device
is to give
‘smoother’engine running when the
en-
,gine
is
qold,,
compensating for the
greater
resistances,
due to friction,
‘4th
an increased fuel supply.
J
Supplementary air solenoid valve
AIR
FLOW~
$ENSORJ~~NTR~L
UNIT
1
The
air flow
sensor
has the task of
fur-
nishing the e(ectronic’CU with an
elec-
trie signa!,
;by
means
of a
potentiome-
ter, with
re’lation:
to the air flow taken
jn
by the engme!This signal is used by
tbe
CU to
;determine,
the
duration
of
the
injection
itime.
The sensitive element is a floating
throttle which opens according to the
amount of air taken in (a
function
of
the
engin+
r.~p.m.
and the opening of
,the
accelerator throttle). The angular
~Position
of~the
floating throttle is
mea-
sured by a
~poientiometer
which is
~~firmly
fixed
to
the spindle of the
floa-
,ting
throttle Itself.
A compensating throttle coupled to
the floating throttle compensates for
any
oscillations in the pressure of the
,flow
due to
badkflow
that
may
occur,
~eo’that
thesd do not affect the
measu-
,rtng
of the air
fl;ow.
#A
sensor for measuring the temperatu-
ire
of the
a,ir
tak~en
in is located at the
,~entrance
of
lthe,
air flow
sensor.
The
$lectr,onic
CU for the control and
mo-
‘initoring
off
the
whole
injection system
~$s
loc’ated
‘in~
the
Upper
part
(caver)
of
‘/the
air flow
sensor.
_
,’
TEMPERATURE
SENSOR
~~
~ ~
~,
IQLE
ADJl/STMENT
BY-PASS
When starting the engine from
cold,
during
the warming up of the engine,
~
A tube connecting the corrugated air
the engine requires a considerably en-
intake
sleeve#with
the supply manifold
riched
mixture. This enrichement must
acts
as a
by;pass
to’
the accelerator
be reduced as
themtemperature
of the
throttle; the ‘amount of air that
cari
engine increases and eliminated when
pass through, this tube cari be varied
the engine reaches normal
running’
i
,,
by
means
ofI
an adjusting screw. By
temperature.
acting on this adjusting screw the’jdle
These variations in temperature
:are
transmitted to electronic CU by
the,
~’
r.4.m.
of
the.
engine
cari
be altered
wi-
thout affectrng.the exhaust CC%.
coolant
temperature
sensor
and
the:
~
‘,
In;fact, the variation in the amount of
CU then control the quantity of fuel in-
”
air taken in by the engine whsn this
jected.
screw is adjusted is measured by the
air flow
sensor
which in turn
provides
for the proportional correction of the
quantity of fuel that is injecfed.
1
Engine
coolant
temperature
sensor
SWITCH ON BODY
OF ACCELERATOR
THROT-
TLE
The switch on the throttle body is firm-
,.
ly fixed to the spindle of the
accelera-
~
1
lLo6k
nut
tor throttle valve. The switch contains 2
~
rldle
r.p.m:
adjusting screw
‘October
1988
,,
A
a full load contact. In this way a
signal
is sent to the electronic CU when the
‘en’gine
is running under conditions of
‘full load and the CU is
able
to alter the
air-petrol ratio according to the
requi-
rements of
th,ese
engine conditions.
When the aceelerator is released the
fuel supply is
tut
off by
means
of the
minimum throttle opening switch.
When the accelerator throttle valve
closes and the engine r.p.m.
(s
higher
than 1600 r.p.m., the fuel’supply is
tut
off until the engine r.p.m. cornes down
to:
1100 rpm approx., where
‘the
fuel
1 Air flow sensor
COOLANT
supply is restored. The main
purpose
of fuel tut-off when the accelerator is
released is to reduce both fuel
con-
sumption and the emission of unburnt
hydrocarbons which usually form
du-
ring this phase.
04-6
PA32 790088330 1
”