Facom X.730B Guía De Instrucciones página 8

No variations or wrong variations could
be caused by: diaphragm of the vacuum
advance variator cracked.
Note : In breaker points systems, an
excessive wear of the distributor's parts
causes abnormal advance variations and
a decreased engine performance. A too
low Dwell angle causes an insuffi cient
ignition; a too high Dwell angle causes a
premature burning of contacts. Remember
to check the advance after repair.
6. CHECKING THE RPM NUMBER
• Reading up to 19 990 RPM can be made
through the inductive clamp.
Direct measurements up to 6000 RPM are
possible with the stroboscope. In this case
refer to page 7.
• In carburettor systems and in some early
electronic injection systems, adjust the ad-
vance through the special screw for a correct
air/petrol mixture until obtaining a regular
engine rotation.
Note : A perfect idle adjustment limits
fuel consumption, emission of harmful
exhaust gases and avoids engine stops.
7. CHECKING BREATHER PIPES
• The check is made by disconnecting the
tubes that go from the crankcase to the
engine head or to the carburettor. By closing
the top of the tube with a fi nger, a drop of
50 or more RPM should occur. If not, check
that there are no fi lter occlusions or possible
damages of the pipe's valves.
8. CHECKING THE MECHANICAL
POSITION OF TIMING MARKS
• To check only the timing marks' position,
bring the display to 00,1 through the C– key.
• Bring the engine to idle and disconnect the
vacuum tube or observe the instructions of
the manufacturer.
By pressing the D key, the timing light
should fl ash.
If the timing mark is too far from the correct
position, rotate the distributor or check
that the distribution belt has not jumped a
cog. The same procedure may be used for
checking the marks of centrifugal advance.
In systems with ECU, check the engine
temperature sensor.
9. ADVANCE MEASUREMENT
• Check that the RPM number is the same
shown in the manufacturer's data.
• Press the C± key until the display shows
the number of degrees indicated in the
manufacturer's data.
Lighten the TDC marks on the pulley and
crankcase taking care not to confuse them
with the other ones.
Check that the error in the alignment of
TDC marks is within the tolerances foreseen
by the manufacturer, otherwise turn the
distributor. In ECU systems, check that the
timing belt has not jumped a cog or that
the engine temperature sensor is not faulty.
• If the TDC mark swings too much check
the distribution belt and the distributor
mechanisms in point systems.
Note : In some vehicles, reference marks
can be better lightened by keeping the
timing light in an uncomfortable position
for the reading. In this case store the
reading when the marks are aligned by
releasing the key D, then read the value
within 6 seconds.
1 0 . C E N T R I F U G A L A D VA N C E
MEASUREMENT
• Run the engine to the speed indicated in
the data manual.
• Press the C± key until the display shows
the number of degrees indicated in the
data manual or in manufacturer's data;
TDC marks on the crankcase and on the
crankshaft pulley should be in line.
If the error is excessive, check the engine
temperature sensor in ECU systems; if the
mark swings too much, or moves irregularly
during accelerations, check that the timing
belt is not loose.
In points systems check the contact spring;
the centrifugal mechanism could otherwise
be worn as well as the pivots or the distri-
butor shaft.
Note : A faulty centrifugal timing can result
in lack of pick-up and fl at points in engine
power at certain engine speeds.
6
11. CHECKING THE VACUUM
ADVANCE
• By connecting the vacuum tube, advance
should increase. It can be measured by
bringing TDC marks in line.
In points systems: if there is no variation or
if the advance is too much out of tolerances,
the diaphragm and the baseplate should be
checked.
Note : In ECU controlled ignition/injection
systems, if the advance caused by the
vacuum device does not correspond
to the manufacturer's specifi cations, it
can be due to a wrong operation of the
vacuum sensor.
12. CHECKING THE ACCELERATION
RETARD
This check can be made in engines provided
with this device.
• Press the C± key to bring the display to
00,1. By connecting the vacuum retard tube
during sudden accelerations, the advance
should momentarily decrease.
In case of anomalous variations, check the
diaphragm or other mechanical parts.
13. VOLTAGE MEASUREMENTS
Measurements of direct battery voltage at
cranking, alternator's charge, voltage varia-
tions on temperature sensors, throttle po-
tentiometer, peak voltage of TDC inductive
sensors, RPM sensors or the control signal
sent by the ECU to the ignition modules can
be made by connecting the RED 1 clip to the
signal contact.
14. RESET
If the timing light display should show faults
while connecting the RED/ BLACK power
clips or during operation, take the timing
light away from possible noise sources
(spark cables, distributors, alternators) and
press RESET.
EN