Fuel-Injection System Depressurisation; Fuel-Injection System Relays Location; Fuel-Injection System - Idle Speed And Mixture Adjustment - Ford Scorpio Owner's Manual

4•14 Fuel and exhaust systems
16 Start the engine and note the engine
speed (rpm). The engine speed should
increase above the normal idle speed, and
should be as given in the Specifications.
17 If the engine speed is not as specified,
remove the tamperproof plug from the top of
the throttle kicker housing, and turn the
adjustment screw to give the specified speed.
18 On completion of adjustment, fit a new
tamperproof cap.
19 Disconnect the tubing from the inlet
manifold, and reconnect the throttle kicker
vacuum hose.
20 Refit the plastic shield and the air cleaner.
28 Fuel-injection system -
depressurisation
On 2.4 & 2.9 litre V6 models especially,
residual pressure will remain in the fuel lines
long after the vehicle was last used therefore
the fuel system must be depressurised before
any hose is disconnected; the system is
depressurised via the vent valve on the fuel
rail, noting that it may be necessary to depress
the valve several times before the pressure is
fully released. As an added precaution place a
rag over the valve as it is depressed to catch
any fuel which is forcibly expelled. Before
carrying out any operation on the fuel system
refer to the precautions given in Safety first! at
the beginning of this Manual and follow them
implicitly. Petrol is a highly dangerous and
volatile liquid and the precautions necessary
when handling it cannot be overstressed.
29 Fuel-injection system relays -
location
Access to the relays is obtained by
removing the facia top cover (crash pad).
The relays are located on the passenger
side (see illustration). Also see Chapter 13,
Section 16.
30 Fuel filter - renewal
See Chapter 1, Section 41.
31.9 Idle mixture adjustment - fuel-injection
models
29.2 Fuel injection system relays - 2.4 and
2.9 litre V6 engines
A Power relay B Fuel pump relay
31 Fuel-injection system - idle
speed and mixture adjustment
SOHC and 2.8 litre V6 engines
1 Idle speed is controlled by the EEC IV
module and no direct adjustment is possible.
2 Idle mixture adjustment should not be
necessary on a routine basis. After component
renewal or a similar circumstance it may be
checked and adjusted as follows.
3 The engine must be at operating temperature.
The valve clearances must be correct, the air
cleaner element must be clean and the ignition
system must be in good condition.
4 Connect an exhaust gas analyser (CO
meter) and a tachometer (rev. counter) to the
engine as instructed by their makers.
5 Run the engine at 3000 rpm for 15 seconds,
then allow it to idle. Repeat the procedure
every 60 seconds until adjustment is
complete.
6 With the engine idling after the 3000 rpm
burst, record the CO level when the reading
has stabilised. The desired value is given in the
Specifications.
7 If adjustment is necessary, remove the
tamperproof plug from the mixture adjusting
screw on the underside of the vane airflow
meter (see illustration).
8 On V6 models, note that adjustment should
first be carried out on the front airflow meter.
31.18 Remove the cover from the mixture
adjustment potentiometer
31.7 Tamperproof plug (arrowed) covering
mixture adjusting screw
Airflow meter is inverted for photo
The rear meter should only be adjusted if the
range of adjustment on the front meter is
insufficient.
9 Turn the mixture adjusting screw with a
hexagon key until the CO level is correct (see
illustration).
10 Stop the engine and disconnect the test
gear.
11 Fit a new tamperproof plug if required.
DOHC engine
Note: Before carrying out any adjustments
ensure that the ignition timing and spark plug
gaps are as specified. To carry out the
adjustments, an accurate tachometer and an
exhaust gas analyser (CO meter) will be
required.
12 Idle speed is controlled by the EEC IV
module, and manual adjustment is not possible,
although the "base" idle speed can be adjusted
by a Ford dealer using special equipment.
13 On models with a catalytic converter, the
mixture is controlled by the EEC IV module,
and no manual adjustment is possible.
14 On models without a catalytic converter,
the idle mixture can be adjusted as follows.
15 Run the engine until it is at normal
operating temperature.
16 Stop the engine and connect a tachometer
and an exhaust gas analyser in accordance
with the manufacturer's instructions.
17 Start the engine and run it at 3000 rpm
for 15 seconds, ensuring that all electrical
loads (headlamps, heater blower, etc) are
switched off, then allow the engine to idle, and
check the CO content. Note that the reading
will initially rise, then fall and finally stabilise.
18 If adjustment is necessary, remove the
cover from the mixture
potentiometer (located on the right-hand side
of the engine compartment, behind the MAP
sensor), and turn the screw to give the
specified CO content (see illustration).
19 If adjustment does not produce a change
in reading, the potentiometer may be at the
extreme of the adjustment range. To centralise
the potentiometer, turn the adjustment screw
20 turns clockwise followed by 10 turns anti-
clockwise, then repeat the adjustment
procedure.
adjustment