1995 ISUZU TROOPER Workshop Manual

IGNITION SYSTEM 6D4 - 1
SECTION 604
IGNITION SYSTEM
CONTENTS
General Description ...................... .
Diagnosis
................................... .
On-Vehicle Service ....................... .
Spark Plug Wire ....................... .
Spark Plug .............................. . 6D4-1
6D4-2 6D4-3
6D4-3
6D4-3
Electronic Ignition (EI) Assembly ...
Crankshaft Position Sensor
(CKP sensor) ........................ .
Torque Specifications
................ .
Main Data and Specifications
......... . 6D4-5
6D4-5
6D4-6
6D4-7
GENERAL DESCRIPTION
Ignition is done by the Electronic Ignition (EI) that
fires directly the ignition plugs from ignition coils
through spark plug wires without using a distributor.
A pair of ignition coils for the cylinders having differ­
ent phases by 360° (No.1 and No.4, No.2 and No.5,
No.3 and No.6) are
fired simultaneously.
Since the cylinder on exhaust stoke requires less
energy to fire its ignition plug, energy from the
ignition coils can be utilized to fire the mating cylin­
der on compression stroke. After additional 360°
rotation, respective cylinder stokes are reversed.
TheEl consists of three ignition coils, ignition control
module, crank angle sensor, Engine Control Module
(ECM) and other components.
Module is provided under the ignition coil, connected
with ECM by means of 6-pin connector. The
ignition control module turns on/off the primary
circuit of ignition coils, and also it controls the igni­
tion timing at the engine
speed below 538 rpm.
A notch in
the timing disc on the crankshaft activates
the crank angle sensor which then sends information
such as firing order and starting timing of each
ignition coil to the ECM.
Further, the El employs Ignition Control (I C) to control
similar to a distributor system.
By receiving
signals such as crank position, engine
speed, water temperature and Manifold Absolute
Pressure (MAP), the ECM controls the ignition timing.

604-2 IGNITION SYSTEM
IGNITION SWITCH
Key
Key Battery
Ignition Battery Acc111ories Ignition
Starter Position 81 IG1 82 ACC IG2 ST
LOCK Removed
BATTERY OFF
/'1 ~ o-
~ Inserted ...... {) ACC ..., -
ON ...... ..... ...... ...... ...... ~ -.....
a: ...... -lXI START Q II) '-' '-' ...., ,_,
BOA 50 A
I 1 MAIN K~YSW 3WB
FL-1 FL-2 3BY -15A 15A IG.COIL ENGINE
ACG (IG)
ELECTRONIC
IGNITION ECM (CONNECTOR) > 1.25 r--""
~~ ~~ BO o""' I
~
1.25 B rrvl -~~ ' f"--~ CONNECTOR C-1
_l_ .... __ .J ~~ c1 mp Shr (E-18)
(C-1) B8 0.85 VB ,, ... , ~~ R!'i YR I I Cl.lo
I !ita lui (C-1) 89 I 0 0.5 BR d 0: IBIBIIIINIBI111Io
(C-2) 05 0.85Y "'I I I > ---(C-2) 011 I
I
)+ 0.85 '-'I a:
~~ ,_, <( TACHO YG (E-21)
~
;;!] METER ,:. .... , a: ~~ 0.5WR q 0! 0... ~~
0.5W I ~$ ... _, ~0 c ( (E-22)
(E-27) CONNECTOR C-2
CRANKSHAFT POSITION .::::> rL
r;::::l enD. .-SENSOR I~ ~~
~ ~ ~~ rt~·· IC4 IT>TiiTiil
f §~
~g l CIJ 0::
·~'l
IGNITION IGNITION CONTROL
COIL MODULE tii1it SPARK PLU Fig. 604-1
DIAGNOSIS
Refer to Section 6E for the diagnosis to the Electronic
ignition system (EI system).
•

IGNITION SYSTEM 604 - 3
ON-VEHICLE SERVICE
SPARK PLUG WIRES
EJ REMOVAL
Preparation
• Disconnect battery ground cable.
1. Spark plug wires (Fig. 604-2)
Fig. 6D4-2
(1!] INSPECTION AND REPAIR
Check the high tension cable for insulation. Check
terminals for corrosion or damage, and replace as
necessary.
Measuring resistance of spark plug wires (kQ)
Spare plug wires SOHC DOHC
No.1 cable 6.4-14.9 6.2-14.2
No.2 cable 5.7-13.1 7.2-16.7
No.3 cable 6.2-14.4 6.5-14.9
No.4 cable 5.8-13.3 6.8-15.8
No.5 cable 6.4-14.9 6.9-16.0
No.6 cable 6.9-16.0 6.3-14.5
Measure resistance
of spark plug wires, and replace
the cable if its value exceeds the standard. (Fig. 6D4-
3)
Fig. 6D4-3
B INSTALLATION
1. Spark plug wires
• Connect ignition coils and spark plugs with
spark plug wires respectively. Match each
number (cylinder No.) marked on the ignition
coil with that on spark plug wire, and connect
each spark
plug for the cylinder. (Fig. 6D4-4)
LH bank
y Front
#4-­
#1--
1®®®1
RH Bank
Connecting Position of Spark plug wire
Fig. 6D4-4
• Connect battery ground cable.
"f CAUTION
Do not cross, twist or pull the spark plug wires.
SPARK PLUG
EJ REMOVAL
1. Spare plug wires
2. Spark plugs (Fig. 604-5)

604-4 IGNITION SYSTEM
Fig. 604A-5
~ INSPECTION AND REPAIR
The spark plug affects entire engine performance and
therefore its inspection is very important.
• Check electrode and insulator for presence of
crack, and replace if any.
• Check electrode for wear, and replace if neces­
sary.
• Check gasket for damage, and replace if neces­
sary.
• Measure insulation resistance with an ohmmeter,
and replace if faulty.
• Adjust spark plug gap to 1.0(0.04) -1.1 (0.043)
mm(in).
• Check fuel and electrical systems if spark plug is
extremely dirty.
• Use spark plugs having low heat value (hot type
plug) if fuel and electrical systems are normal.
• Use spark plugs having high heat value (cold type
plug) if insulator and electrode are extremely
burned.
Sooty spark plugs
Much deposit of carbon or oil on the electrode and
insulator of spark plug reduces the engine perfor­
mance.
Possible causes:
• Too rich mixture
• Retarded ignition timing
• Presence of oil in combustion chamber
• Incorrectly adjusted spark plug gap
Burning electrodes
This fault is characterized by scorched or heavily
oxidized electrode or blistered insulator nose.
Possible causes:
• Too lean mixture
• Advanced ignition timing
• Improper heat value
Measuring Insulation Resistance
• Measure insulation resistance using a 500 volt
megaohm meter. (Fig. 604-6)
Fig.
604-6
• Replace spark plugs if measured value is out of
standard.
I @!.j Insulation resistance MQ 50 or more
Cleaning Spark Plugs
• Clean spark plugs with a spark plug cleaner.
• Raise the ground electrode to an angle of 45 to 60
degrees. If electrode is wet, dry it before cleaning.
• After spark plug is thoroughly cleaned, check
insulator for presence of crack.
• Clean threads and metal body with a wire brush.
• File the electrode tip if electrode is extremely
worn.
• Bend the ground electrode to adjust the spark
plug gap. (Fig. 604-7)
Fig. 604-7
•

[!!) INSTALLATION
2. Spark plugs
• Tighten spark plugs to the specified torque.
1. Spark plug wires
• Connect high tension cables to correct termi­
nals respectively.
~~~ Torque N·m (lb·ft) I
ELECTRONIC IGNITION (EI)
ASSEMBLY
EJ REMOVAL
Preparation
• Disconnect battery ground cable
1. Spark plug wires
2. Wiring connectors
18 (13)
• Disconnect connectors on Engine Control
Module (ECM), power supply and crank angle
sensor.
3. Electronic Ignition (EI) assembly
• Remove three fixing bolts, then the El assem­
bly. (Fig. 6D4-8)
Fig. 6D4-8
E]INSTALLATION
Electronic Ignition (Ell assembly
3. Electronic Ignition (EI) assembly
~~~ Torque N·m (lb·ftl I 19 (14)
2. Wiring connector
Connect connectors to ECM, power supply and
crank
angle sensor.
IGNITION SYSTEM 604-5
1. Spark plug wires
• Connect Spark plug wires to correct terminals.
• Connect battery ground cable.
CRANKSHAFT POSITION SENSOR
(CKP Sensor)
E) REMOVAL
Preparation
• Disconnect battery ground cable
•
Remove exhaust & transfer protector
• Disconnect front propeller shaft joint. (Fig.
6D4-9)
Fig. 6D4-9
1. Wiring connector
2. Mounting nut
3. Crankshaft position sensor (CKP sensor) (Fig.
604-10)
Fig. 6D4-10