trunk FORD FIESTA 1989 Service Repair Manual

SEFi fuel injection models
7Disconnect the mass air flow sensor wiring
multi-plug (see illustration) .
8 Slacken the hose clip and disconnect the
flexible rubber intake hose from the black
plastic air intake duct (see illustration).
9 Undo the retaining screws or release the
clips and lift off the air cleaner lid complete
with mass air flow sensor (see illustration).
All models
10Lift out the element, and wipe out the
housing (see illustrations) . Check that no
foreign matter is visible, either in the air inlet
or in the air mass meter, as applicable.
11 If carrying out a routine service, the
element must be renewed regardless of its
apparent condition. Note that on models so
equipped, the small foam PCV filter in the rear
right-hand corner of the air cleaner housing
must be cleaned whenever the air filter
element is renewed (see Section 25).
12 If you are checking the element for any
other reason, inspect its lower surface; if it is
oily or very dirty, renew the element. If it is
only moderately dusty, it can be re-used after
blowing it clean from the upper to the lower
surface with compressed air. Warning: Wear eye protection
when using compressed air!
Because it is a pleated-paper
type filter, it cannot be washed
or re-oiled. If it cannot be cleaned satisfactorily with compressed air,
discard and renew it.
Caution: Never drive the vehicle with the
air cleaner filter element removed.
Excessive engine wear could result, and
backfiring could even cause a fire under
the bonnet.
13
Refitting is the reverse of the removal
procedure. Ensure that the element and cover
are securely seated, so that unfiltered air
cannot enter the engine.Air cleaner temperature control
system check (carburettor
models)
14 In order for the engine to operate
efficiently, the temperature of the air entering
the inlet system must be controlled within
certain limits.
15 The air cleaner has two sources of air, one
direct from the outside of the engine
compartment, and the other from a shroud on
the exhaust manifold. On HCS engines, a
wax-controlled thermostatic valve controls a
flap inside the air cleaner inlet. When the
ambient air temperature is below a
predetermined level, the flap admits air
heated from the exhaust manifold shroud; as
the ambient temperature rises, the flap opens
to admit more cool air from the engine
compartment until eventually it is fully open. A
similar system is used on CVH engines,
except that a vacuum actuator modifies any opening or closing action of the temperature
sensor on the flap valve, according to the level
of the inlet manifold vacuum under running
conditions.
HCS engines
16
This check must be made when the
engine is cold. Detach and remove the air
cleaner inlet trunking. Examine the position of
the check valve within the duct. When the
underbonnet air temperature is below 28ºC,
the valve must be open to allow hot air to
enter the filter (see illustration) .
17 Refit the inlet trunking. Start the engine
and run it until it reaches its normal operating
temperature, then stop the engine, remove
the inlet trunking and check that the valve has
closed off the air passage from the exhaust
and opened the main (cool) air inlet.
18 If the flap does not operate correctly,
check that it is not seized. Apart from this
there is no adjustment possible, and the unit
should be renewed if faulty. Refit the air inlet
trunking on completion.
CVH engines
19 This check must be made when the
engine is cold. Disconnect the main air inlet
duct, and visibly check that the flap to the
hot-air inlet is closed (i.e. open to the passage
of cold air).
20 Start the engine, and check that with the
Every 30 000 miles or three years1•23
24.9 . . . then undo the retaining screws or
release the clips and lift off the air cleaner lid complete with mass air flow sensor24.8 . . . slacken the hose clip and
disconnect the intake hose from the air intake duct . . .24.7 On SEFi fuel injection engines,
disconnect the mass air flow sensor wiring multi-plug . . .
24.16 Air cleaner inlet and flap valve onthe HCS engine
A Main air cleaner inlet (cool air)
B Warm air duct (flap open)
24.10b . . . and on EFi and SEFi fuel injection engine models24.10a Removing the air filter element oncarburettor engine models . . .
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