1994 MITSUBISHI 3000GT Workshop Manual

Downloaded from www.Manualslib.com manuals search engine ENGINE ELECTRICAL - Ignition System16-43
Wave-form Observation Points/
LPoint A: The height, length and slope of the spark line (refer to abnormal wave-form examples 1, 2, 3and 4) show the following trends.
Spark linePlug gapCondition of CompressionConcentra-Ignition timing High tension
electrodeforcetion of air mix-cable
tureLength Long
SmallNormalLowRichAdvanced
Leak
Short
LargeLarge wearHighLeanRetardedHigh
resistanceHeight High
LargeLarge wearHighLeanRetardedHigh
resistance
LowSmall
NormalLowRichAdvancedLeak
SlopeLargePlug is fouled-
Point B: Number of vibrations in reduction vibration section
(Refer to abnormal wave-form example 5)
Number of vibrationsCoil and condenser
I3 or higher/ Normal
Except aboveAbnormal
Point C: Height of Zener voltage
Height of Zener voltageProbable cause
HigherProblem in Zener diode
LowerAbnormal resistance in pri-
mary coil circuit
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Downloaded from www.Manualslib.com manuals search engine ENGINE ELECTRICAL - Ignition System
EXAMPLES OF ABNORMAL WAVE-FORMS
Abnormal wave-form
Wave characteristics
Cause of problem
Example 1Spark line is high and short.
Spark plug gap is too large.
z01P0210
Example 2Spark line is low and long, and is
sloping. Also, the second half of
Spark plug gap is too small.the spark line is distorted. This
could be a result of misfiring.3
i
Example 3
zo1Po211
Spark line is low and long, and is
sloping. However, there is almostSpark plug gap is fouled.
no spark line distortion.
ZOlPO212
Example 4Spark line is high and short.Spark plug cable is nearly falling
off. (Causing a dual ignition)
ZOlPO213
Example 5No waves in wave damping set-tion.Rare short in ignition coil.
-l
zolPo214
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IGNITION SYSTEM
LREMOVAL AND INSTALLATIONI
i
27EN0520
413 NmIlOft.lbs.
d
12 Nm
9 ft.lbs.
22 Nm16ftAbs.B678
W1
,A4
Removal stepsl Intake manifold plenum (Refer to
GROUP
1.5 - Intake Manifold.)1. Center cover
2. Spark plug cable
3. Spark plug
4. Ignition coil
5. Ignition power transistor
6. Crankshaft position sensor
cl 992 models>9 Nm
7
ft.lbs.u 16FO453
00662527
7. O-ring cl992 models>
8. Clamp Camshaft position sensor, Crankshaft
positionsensor removal steps models>l Timing belt cover (Refer to GROUP
11 - Timing Belt)
9. Camshaft position sensor
10. Crankshaft position sensor
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Downloaded from www.Manualslib.com manuals search engine 16-46ENGINE ELECTRICAL - Ignition Svstem
27ELOO95JINSTALLATION SERVICE POINTS.A+CRANKSHAFT
POSITION SENSOR INSTALLATION

(1) Turn the crankshaft so that the No. 1 cylinder is at
compression top dead center.
Caution
Be careful not to turn it to the No.
4 cylinder com-
pression top dead center by mistake.
(2) Install, lining up the matchmarks on the crankshaft
position sensor housing and the coupling.
,B+SPARK PLUG CABLE INSTALLATION
Improper arrangement of spark plug cables will induce
voltage between the cables, causing miss firing and devel-
oping a surge at acceleration in high-speed operation.
Therefore, be careful to arrange the spark plug cables
properly by the following procedure.
1.install the spark plug cable clamps as shown in the
illustration.
2.The numerals on the support and clamp indicate the
spark plug cable No.
3.Pay attention to the following items when the spark
plug cables are installed.
(1)Install the cables securely to avoid possible contact
with metal parts.(2) Install the cables neatly, ensuring they are not
too tight, loose, twisted or kinked.
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Spark plugcable No. 1
Spark plugr cable No. 4
\Spark plug‘de No. 6
sparK piug
cable No. 2
Approx.60 mm
(2,36in.) Approx
I(3.15in.)cup to 1992
model>
Approx. 80 mm (3.15 in.)TIC only

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Downloaded from www.Manualslib.com manuals search engine 16-48ENGINE ELECTRICAL - lanition Svstem
\/27EL0086
/DEL0087INSPECTION
SPARK PLUGCheck the plug gap and replace if the limit is exceeded.
Standard value:
1.0-l .l mm (.039-.043 in.)
Limit: 1.3 mm
(.051 in.)
Caution
1.Do not attempt to adjust the gap of the platinum plug.
2.Cleaning of the platinum plug may damage the plati-num tip. Therefore, if carbon deposits must be re-
moved, use a plug cleaner and complete cleaning with-
in 20 seconds for protection of the electrode. Do not
use wire brushes.
SPARK PLUG CABLE(1) Check cap and coating for cracks.
(2) Measure resistance.Limit: Max. 22
ksZ
IGNITION POWER TRANSISTOR
NOTE
An analog-type circuit tester should be used.No. l-No. 4 coil side
(1)Connect the negative (-) terminal of the 1.5 V power supply
to terminal (4) of the ignition power transistor; then check
whether there is continuity between terminal (13) and termi-nal (4) when terminal (3) and the positive
(+) terminal
are connected and disconnected.NOTE
Connect the (-) probe of the circuit tester to terminal (13).
Terminal 3 and (+) terminal
ConnectedTerminal 13 and terminal 4
Continuity
IUnconnectedINo continuitv
(2)Replace the ignition power transistor if there is a malfunc-
tion.No. ~-NO. 5 coil side
(1)Connect the negative (-) terminal of the 1.5 V power supply
to terminal (4) of the ignition power transistor; then check
whether there is continuity between terminal (12) and termi-nal (4) when terminal (2) and the positive
(+) terminal
are connected and disconnected.
NOTE
Connect the (-)
probe of the circuit tester to terminal (12).
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27EL0089
Z7ELOOQO
1 Terminal 2 and (+) terminal/Terminal 12 and terminal 41
IConnectedIContinuitvI
IUnconnectedINo continuitvI
(2) Replace the ignition power transistor if there is a malfunc-
tion.No. ~-NO. 6 coil side
(1)Connect the negative (-) terminal of the 1.5 V power supply
to terminal (4) of the ignition power transistor; then check
whether there is continuity between terminal (11) and termi-nal (4) when terminal (1) and the positive
(+) terminal
are connected and disconnected.
NOTE
Connect the (-) probe of the circuit tester to terminal 11.
I Terminal 1 and (+) terminal/ Terminal 11 and terminal 41
-ConnectedIContinuityI
IUnconnectedINo continuityI
(2)Replace the ignition power transistor if there is a malfunc-
tion.
IGNITION COIL
Primary Coil Resistance
Measure the resistance between connector terminal (3) (pow-
er) and each coil terminal.Measuring point:
Coil A
(No.l-No.4 cylinder side coil) . . . . . . (2)-(3)Coil B (No.2-No.5 cylinder side coil) . . . . . .
(l)-(3)Coil C (No.3-No.6 cylinder side coil) . . . . . .
(4)-(3)Standard value: 0.67-0.81
Sz
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Secondary Coil Resistance
Measure the resistance between each coil high voltage termi-
nals.
Measuring point:Coil A (No. l-No. 4 cylinder side coil)
Coil B (No. ~-NO. 5 cylinder side coil)
Coil C (No. ~-NO. 6 cylinder side coil)
Standard value: 11.3-15.3
Wz

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