Advertisement
.
1-26 GENERALINFORMATIONAND
MAINTENANCE
TDC of the compression stroke. If this happens, the
piston WIII be at the beginning of the power stroke
just as the compressed and ignited air/fuel mixture
forces the piston down and turns the crankshaft. Be-
cause it takes a fraction of a second for the spark
plug to ignite the mixture in the cylinder, the spark
plug must fire a little before the piston reaches TDC.
Otherwise, the mixture will not be completely ignited
as the piston passes TDC and the full power of the
explosion will not be used by the engine.
The timing measurement is given in degrees of
crankshaft rotation before the piston reaches TDC
(BTDC). If the setting for the ignition timing is 10"
BTDC, each spark plug must fire 10 degrees before
each piston reaches TDC. This only holds true, how-
ever, when the engine is at idle speed. The combus-
tion process must be complete by 23"ATDC to main-
tain proper engine performance, fuel mileage, and
low emissions.
As the engine speed increases, the pistons go
faster. The spark plugs have to ignite the fuel even
sooner if it IS to be completely ignited when the pis-
ton reaches TDC. If the ignition is set too far ad-
vanced (BTDC), the ignition and expansion of the fuel
in the cylinder wtll occur too soon and tend to force
the piston down while it is still traveling up. Thus
causes pre ignition or "knockmg and pinging". If the
ignition spark is set too far retarded, or after TDC
(ATDC), the piston will have already started on its
way down when the fuel is ignited. The piston will be
forced down for only a portion of its travel, resulting
in poor engine performance and lack of power.
Timing marks or scales can be found on the rim of
the crankshaft pulley and the timing cover. The marks
on the pulley correspond to the posrtion of the piston
in the No. 1 cylinder. A stroboscopic (dynamic) tim-
ing light is hooked onto the No. 1 cylinder spark plug
wrre. Every time the spark plug fires, the timing light
flashes. By aiming the light at the timing marks while
the engine is running, the exact position of the piston
within the cylinder can be easily read (the flash of
light makes the mark on the pulley appear to be
standing still). Proper timing is indicated when the
mark and scale are in specified alignment.
When checking timing with the engine run-
ning, take care not to get the timing light
wires tangled in the tan blades and/or drive
belts.
INSPECTION &ADJUSTMENT
1990-96 Models
e See Figures 113 thru 119
1. Set the parking brake, start and run the engine
until normal operating temperature is obtained. Keep
all lights and accessories OFF and the front wheels
straight-ahead. Place the transaxle in
P
for automatic
transaxle or Neutral for manual transaxle.
2. If not at specification, set the idle speed to the
correct level.
3. Turn the engine
OFF.
Remove the water-
proof cover from the igmtion timing adjusting con-
nector, and connect a jumper wire from this terminal
Fig. 113 Ignition timing adjustment con-
nector-1990-92 Mirage with 1.5L engine
93151QM
Fig. 115 Ignition timing adjustment con-
nectar-Galant with 2.OL engines
93151QO1
Fig. 117 Ignition timing adjustment con.
nectar-1994-96 Galant
to a good ground. Refer to the corresponding illustra-
tions for the correct location of the timing adjustment
connector.
4. Connect a conventional power timing light to
the No. 1 cylinder spark plug wire. Start the engine
and run at idle.
5. Aim the timing light at the timing scale lo-
cated near the crankshaft pulley.
6. Loosen the distributor or crank angle sensor
hold-down nut just enough so the housing can be ro-
tated.
7. Turn the housing in the proper direction until
the specified timing is reached. Tighten the hold-
down nut and recheck the timing. Turn the engine
OFF.
8. Remove the jumper wire from the ignition
timing adjusting terminal and install the water-proof
cover.
9. Start the engine and check the actual timing
(the timing without the terminal grounded). This
reading should be approximately 5 degrees more
than the basic timing. Actual timing may increase ac-
cording to altitude. Also, actual timing may fluctuate
because of slight variation accomplished by the ECU.
Fig. 114 Ignition timing adjustment con-
nectar-Miracle with 1.6L enaine
CHECK CONNECTOR
93151QO!
Fig. 116 Ignition timing adjustment con.
nectar-1992-96 Oiamante
93151gOB
Fig. 116 Ignition timing adjustment con-
nector-1993-96 Mirage with 1.5L engine
Fig. 119 Ignition timing adjustment con-
nector-1993-96 Mirage with 1.6L engine
As long as the basic timing is correct, the engine is
timed correctly.
10. Turn the engine
OFF.
11. Disconnect the timing apparatus and
tachometer.
1997-00 Models
The ignition timing is controlled by the Engine
Control Module (ECM) and is not adjustable. How-
ever it can be inspected using a scan tool.
Advertisement
