maintenance OPEL FRONTERA 1998 Owner's Manual

DRIVE LINE CONTROL SYSTEM (TOD) 4B2–16
7. Slowly start the vehicle in the 4L mode, and
accelerate to at least 20 km/h. Apply the brake to
completely stop the vehicle.
If the CHECK lamp starts blinking during the test run, read
the trouble codes and give appropriate maintenance
according to the diagnostic procedure. If the TOD
indicator lamps are lit abnormally during the run, check
the lighting condition and give appropriate maintenance
according to the diagnostic procedure. Even if the
phenomena are not observed, try to reproduce the
abnormal state reported by the customer to the possible
extent.
Post-Repair Check
As long as the starter is not turned off, the TOD indicator
lamps continue blinking even after the failed portion
repaired. Therefore, upon completion of repair, be sure to
turn off the starter switch once and then turn on it to
conduct the test run sequence specified in steps 1
through 7 above and check that the TOD indicator lamps
no longer show any faulty status.

4C–2
DRIVE SHAFT SYSTEM
Service Precaution
WARNING: IF SO EQUIPPED WITH A
SUPPLEMENTAL RESTRAINT SYSTEM (SRS),
REFER TO THE SRS COMPONENT AND WIRING
LOCATION VIEW IN ORDER TO DETERMINE
WHETHER YOU ARE PERFORMING SERVICE ON OR
NEAR THE SRS COMPONENTS OR THE SRS
WIRING. WHEN YOU ARE PERFORMING SERVICE
ON OR NEAR THE SRS COMPONENTS OR THE SRS
WIRING, REFER TO THE SRS SERVICE
INFORMATION. FAILURE TO FOLLOW WARNINGS
COULD RESULT IN POSSIBLE AIR BAG
DEPLOYMENT, PERSONAL INJURY, OR
OTHERWISE UNNEEDED SRS SYSTEM REPAIRS.
CAUTION: Always use the correct fastener in the
proper location. When you replace a fastener, use
ONLY the exact part number for that application.
ISUZU will call out those fasteners that require a
replacement after removal. ISUZU will also call out
the fasteners that require thread lockers or thread
sealant. UNLESS OTHERWISE SPECIFIED , do not
use supplemental coatings (Paints, greases, or other
corrosion inhibitors) on threaded fasteners or
fastener joint interfaces. Generally, such coatings
adversely affect the fastener torque and the joint
clamping force, and may damage the fastener. When
you install fasteners, use the correct tightening
sequence and specifications. Following these
instructions can help you avoid damage to parts and
systems.
General Description
This publication contains essential removal, installation,
adjustment and maintenance procedures.
The front axle utilizes a central disconnect type front
axle/transfer case system.
The drive axles are completely flexible assemblies,
consisting of inner and outer constant velocity (CV) drive
shaft joints connected by an axle shaft.
For description of propeller shaft and universal joint, refer
to Front/Rear Propeller Shaft in this section.

6A–16
ENGINE MECHANICAL
Lubrication Problems
ConditionPossible causeCorrection
Oil pressure too lowWrong oil in useReplace with correct engine oil
Relief valve stickingReplace
Oil pump not operating properlyCorrect or replace
Oil pump strainer cloggedClean or replace strainer
Oil pump wornReplace
Oil pressure gauge defectiveCorrect or replace
Crankshaft bearing or connecting
rod bearing wornReplace
Oil contaminationWrong oil in useReplace with correct engine oil
Oil filter cloggedReplace oil filter
Cylinder head gasket damageReplace gasket
Burned gases leakingReplace piston and piston rings or
cylinder body assembly
Oil not reaching valve systemOil passage in cylinder head or
cylinder body cloggedClean or correct
Engine Oil Pressure Check
1. Check for dirt, gasoline or water in the engine oil.
a. Check the viscosity of the oil.
b. Change the oil if the viscosity is outside the
specified standard.
c. Refer to the “Maintenance and Lubrication” section
of this manual.
2. Check the engine oil level.
The level should fall somewhere between the “ADD”
and the “FULL” marks on the oil level dipstick.
If the oil level does not reach the “ADD” mark on the
oil level dipstick, engine oil must be added.3. Remove the oil pressure unit.
4. Install an oil pressure gauge.
5. Start the engine and allow the engine to reach normal
operating temperature (About 80
C).
6. Measure the oil pressure.
Oil pressure should be:
392–550 kPa (56.9–80.4 psi) at 3000 rpm.
7. Stop the engine.
8. Remove the oil pressure gauge.
9. Install the oil pressure unit.
10. Start the engine and check for leaks.

6C–5
ENGINE FUEL
Installation
1. Install the fuel filter in the proper direction.
2. Install fuel filter holder fixing bolt.
3. Connect fuel hoses on engine side(1) and fuel tank
side(2).
041RW001
4. Install fuel filler cap
5. Connect the battery ground cable.
Inspection
After installation, start engine and check for fuel leakage.
In–Tank Fuel Filter
The filter is located on the lower end of fuel pickup tube in
the fuel tank. It prevents dirt from entering the fuel pipe
and also stops water unless the filter is completely
submerged in the water. It is a self cleaning type, not
requiring scheduled maintenance. Excess water and
sediment in the tank restricts fuel supply to the engine,
resulting in engine stoppage. In such a case, the tank
must be cleaned thoroughly.
Fuel Pump Flow Test
If reduction of fuel supply is suspected, perform the
following checks:
1. Make sure that there is fuel in the tank.
2. With the engine running, check the fuel feed pipe and
hose from fuel tank to injector for evidence of
leakage. Retighten, if pipe or hose connection is
loose. Also, check pipes and hoses for squashing or
clogging.
3. Insert the hose from fuel feed pipe into a clean
container, and check for fuel pump flow rate.4. Connect the pump relay terminals with a jumper
wire(1) as shown and start the fuel pump to measure
delivery.
140RW002
CAUTION: Never generate sparks when connecting
a jumper wire.
Delivery
Delivery
15 seconds0.38 liters minimum
If the measure value is out of standard, conduct the
pressure test.
Pressure test
For the pressure test to the fuel system, see Section 6E
“Fuel Control System”.

6D3–18STARTING AND CHARGING SYSTEM
Charging System
General Description
The IC integral regulator charging system and its main
components are connected as shown in the illustration.
The regulator is a solid state type and it is mounted along
with the brush holder assembly inside the generator
installed on the rear end cover.
The generator does not require particular maintenance
such as voltage adjustment.
The rectifier connected to the stator coil has eight diodes
to transform AC voltage into DC voltage.
This DC voltage is connected to the output terminal of
generator.
General On–Vehicle Inspection
The operating condition of charging system is indicated
by the charge warning lamp. The warning lamp comes on
when the starter switch is turned to “ON” position. The
charging system operates normally if the lamp goes off
when the engine starts.
If the warning lamp shows abnormality or if undercharged
or overcharged battery condition is suspected, perform
diagnosis by checking the charging system as follows:
1. Check visually the belt and wiring connector.
2. With the engine stopped, turn the stator switch to
“ON” position and observe the warning lamp.
If lamp does not come on:
Disconnect wiring connector from generator, and
ground the terminal “L” on connector side.
If lamp comes on:
Repair or replace the generator.
F06RW009

6E–1 ENGINE DRIVEABILITY AND EMISSIONS
ENGINE
ENGINE DRIVEABILITY AND EMISSIONS
CONTENTS
Specifications 6E–5. . . . . . . . . . . . . . . . . . . . . . . . .
Tightening Specifications 6E–5. . . . . . . . . . . . . . .
Vehicle Type Specifications 6E–5. . . . . . . . . . . . .
Diagrams and Schematics 6E–6. . . . . . . . . . . . . . . .
PCM Wiring Diagram (1 of 11) 6E–6. . . . . . . . . . .
PCM Wiring Diagram (2 of 11) For EC,
THAILAND, SOUTH EAST ASIA, LATIN
AMERICA, GULF, SAUDI, CHINA. 6E–7. . . . . .
PCM Wiring Diagram (3 of 11) For SOUTH
AFRICA and EXP. 6E–8. . . . . . . . . . . . . . . . . . . . .
PCM Wiring Diagram (4 of 11) 6E–9. . . . . . . . . . .
PCM Wiring Diagram (5 of 11) 6E–10. . . . . . . . . . .
PCM Wiring Diagram (6 of 11) For
AUSTRALIA, THAILAND, SOUTH EAST
ASIA, LATIN AMERICA, GULF, SAUDI,
LATIN AMERICA. 6E–11. . . . . . . . . . . . . . . . . . . . .
PCM Wiring Diagram (7 of 11) For EC. 6E–12. . .
PCM Wiring Diagram (8 of 11) For EXPORT
and SOUTH AFRICA. 6E–13. . . . . . . . . . . . . . . . .
PCM Wiring Diagram (9 of 11) Except EXP
and SOUTH AFRICA 6E–14. . . . . . . . . . . . . . . . . .
PCM Wiring Diagram (10 of 11) For
EXPORT and SOUTH AFRICA 6E–15. . . . . . . . .
PCM Wiring Diagram (11 of 11) 6E–16. . . . . . . . . .
PCM Pinouts 6E–17. . . . . . . . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 32-Way Red
Connector – Row “A” 6E–17. . . . . . . . . . . . . . . . . .
PCM Pinout Table, 32-Way Red
Connector – Row “B” 6E–19. . . . . . . . . . . . . . . . . .
PCM Pinout Table, 32-Way White
Connector – Row “C” (For EC) 6E–20. . . . . . . . . .
PCM Pinout Table, 32-Way White
Connector – Row “C” (For except EC) 6E–21. . .
PCM Pinout Table, 32-Way White
Connector – Row “D”
(For except EXPORT and SOUTH
AFRICA) 6E–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 32-Way White
Connector – Row “D”
(For EXPORT and SOUTH AFRICA) 6E–23. . . . .
PCM Pinout Table, 32-Way Blue
Connector – Row “E”
(For except EXPORT and SOUTH
AFRICA) 6E–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 32-Way Blue
Connector – Row “E”
(For EXPORT and SOUTH AFRICA) 6E–26. . . . .
PCM Pinout Table, 32-Way Blue
Connector – Row “F” 6E–27. . . . . . . . . . . . . . . . . .
Component Locators 6E–28. . . . . . . . . . . . . . . . . . . .
Engine Component Locator (This illustration
is based on RHD model.) 6E–28. . . . . . . . . . . . . . Engine Component Locator Table 6E–29. . . . . . . .
Engine Component Locator Table 6E–31. . . . . . . .
Undercarriage Component Locator 6E–32. . . . . .
Undercarriage Component Locator Table
(Automatic Transmission) 6E–32. . . . . . . . . . . . . .
Undercarriage Component Locator Table
(Manual Transmission) 6E–33. . . . . . . . . . . . . . . .
Fuse and Relay Panel (Underhood
Electrical Center) 6E–33. . . . . . . . . . . . . . . . . . . . .
Sensors and Miscellaneous Component
Locators 6E–34. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnosis 6E–37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Strategy-Based Diagnostics 6E–37. . . . . . . . . . . . .
Strategy-Based Diagnostics 6E–37. . . . . . . . . . . . .
DTC Stored 6E–37
. . . . . . . . . . . . . . . . . . . . . . . . . . .
No DTC 6E–37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
No Matching Symptom 6E–37. . . . . . . . . . . . . . . . .
Intermittents 6E–37. . . . . . . . . . . . . . . . . . . . . . . . . .
No Trouble Found 6E–37. . . . . . . . . . . . . . . . . . . . .
Verifying Vehicle Repair 6E–37. . . . . . . . . . . . . . . .
General Service Information 6E–38. . . . . . . . . . . . . .
OBD Serviceablity Issues 6E–38. . . . . . . . . . . . . . .
Maintenance Schedule 6E–38. . . . . . . . . . . . . . . . .
Visual / Physical Engine Compartment
Inspection 6E–38. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Basic Knowledge of Tools Required 6E–38. . . . . .
Serial Data Communications 6E–38. . . . . . . . . . . . . .
Class II Serial Data Communications 6E–38. . . . .
On-Board Diagnostic (OBD) 6E–39. . . . . . . . . . . . . .
On-Board Diagnostic Tests 6E–39. . . . . . . . . . . . .
Comprehensive Component Monitor
Diagnostic Operation 6E–39. . . . . . . . . . . . . . . . . .
Common OBD Terms 6E–40. . . . . . . . . . . . . . . . . .
The Diagnostic Executive 6E–40. . . . . . . . . . . . . . .
DTC Types 6E–41. . . . . . . . . . . . . . . . . . . . . . . . . . .
Verifying Vehicle Repair 6E–42. . . . . . . . . . . . . . . .
Reading Diagnostic Trouble Codes Using
A Tech 2 6E–42. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tech 2 Tech 2 6E–43. . . . . . . . . . . . . . . . . . . . . . . . .
Tech 2 Features 6E–43. . . . . . . . . . . . . . . . . . . . . . .
Getting Started 6E–44. . . . . . . . . . . . . . . . . . . . . . . .
Operating Procedure (For Example) 6E–44. . . . .
DTC Modes 6E–45. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC Information Mode 6E–46. . . . . . . . . . . . . . . . .
Injector Balance Test 6E–46. . . . . . . . . . . . . . . . . . .
EGR Control Test 6E–47. . . . . . . . . . . . . . . . . . . . . .
Idle Air Control System Test 6E–48. . . . . . . . . . . . .

6E–38
ENGINE DRIVEABILITY AND EMISSIONS
General Service Information
OBD Serviceablity Issues
The list of non-vehicle faults that could affect the
performance of the OBD system has been compiled.
These non-vehicle faults vary from environmental
conditions to the quality of fuel used.
The illumination of the MIL (“Check Engine” lamp) due to
a non-vehicle fault could lead to misdiagnosis of the
vehicle, increased warranty expense and customer
dissatisfaction. The following list of non-vehicle faults
does not include every possible fault and may not apply
equally to all product lines.
Fuel Quality
Using fuel with the wrong octane rating for your vehicle
may cause driveability problems. Many of the major fuel
companies advertise that using “premium” gasoline will
improve the performance of your vehicle. Most premium
fuels use alcohol to increase the octane rating of the fuel.
Although alcohol-enhanced fuels may raise the octane
rating, the fuel’s ability to turn into vapor in cold
temperatures deteriorates. This may affect the starting
ability and cold driveability of the engine.
Low fuel levels can lead to fuel starvation, lean engine
operation, and eventually engine misfire.
Non-OEM Parts
All of the OBD diagnostics have been calibrated to run
with OEM parts. Something as simple as a
high-performance exhaust system that affects exhaust
system back pressure could potentially interfere with the
operation of the EGR valve and thereby turn on the MIL
(“Check Engine” lamp). Small leaks in the exhaust
system near the post catalyst oxygen sensor can also
cause the MIL (“Check Engine” lamp) to turn on.
Aftermarket electronics, such as cellular phones,
stereos, and anti-theft devices, may radiate EMI into the
control system if they are improperly installed. This may
cause a false sensor reading and turn on the MIL (“Check
Engine” lamp).
Environment
Temporary environmental conditions, such as localized
flooding, will have an effect on the vehicle ignition system.
If the ignition system is rain-soaked, it can temporarily
cause engine misfire and turn on the MIL (“Check Engine”
lamp).
Poor Vehicle Maintenance
The sensitivity of OBD diagnostics will cause the MIL
(“Check Engine” lamp) to turn on if the vehicle is not
maintained properly. Restricted air filters, fuel filters, and
crankcase deposits due to lack of oil changes or improper
oil viscosity can trigger actual vehicle faults that were not
previously monitored prior to OBD. Poor vehicle
maintenance can not be classified as a “non-vehicle
fault”, but with the sensitivity of OBD diagnostics, vehicle
maintenance schedules must be more closely followed.Related System Faults
Many of the OBD system diagnostics will not run if the
PCM detects a fault on a related system or component.
One example would be that if the PCM detected a Misfire
fault, the diagnostics on the catalytic converter would be
suspended until Misfire fault was repaired. If the Misfire
fault was severe enough, the catalytic converter could be
damaged due to overheating and would never set a
Catalyst DTC until the Misfire fault was repaired and the
Catalyst diagnostic was allowed to run to completion. If
this happens, the customer may have to make two trips to
the dealership in order to repair the vehicle.
Maintenance Schedule
Refer to the Maintenance Schedule.
Visual / Physical Engine Compartment
Inspection
Perform a careful visual and physical engine
compartment inspection when performing any diagnostic
procedure or diagnosing the cause of an emission test
failure. This can often lead to repairing a problem without
further steps. Use the following guidelines when
performing a visual/physical inspection:
Inspect all vacuum hoses for punches, cuts,
disconnects, and correct routing.
Inspect hoses that are difficult to see behind other
components.
Inspect all wires in the engine compartment for proper
connections, burned or chafed spots, pinched wires,
contact with sharp edges or contact with hot exhaust
manifolds or pipes.
Basic Knowledge of Tools Required
NOTE: Lack of basic knowledge of this powertrain when
performing diagnostic procedures could result in an
incorrect diagnosis or damage to powertrain
components. Do not attempt to diagnose a powertrain
problem without this basic knowledge.
A basic understanding of hand tools is necessary to effec-
tively use this section of the Service Manual.
Serial Data Communications
Class II Serial Data Communications
This vehicle utilizes the “Class II” communication system.
Each bit of information can have one of two lengths: long
or short. This allows vehicle wiring to be reduced by
transmitting and receiving multiple signals over a single
wire. The messages carried on Class II data streams are
also prioritized. If two messages attempt to establish
communications on the data line at the same time, only
the message with higher priority will continue. The device
with the lower priority message must wait. The most
significant result of this regulation is that it provides Tech 2
manufacturers with the capability to access data from any
make or model vehicle that is sold.

6E–345 ENGINE DRIVEABILITY AND EMISSIONS
0014
Crankshaft Position (CKP) Sensor
The crankshaft position (CKP) sensor provides a signal
used by the powertrain control module (PCM) to calculate
the ignition sequence. The sensor initiates the 58X
reference pulses which the PCM uses to calculate RPM
and crankshaft position. Refer to
Electronic Ignition
System
for additional information.
Electronic Ignition
The electronic ignition system controls fuel combustion
by providing a spark to ignite the compressed air/fuel
mixture at the correct time. To provide optimum engine
performance, fuel economy, and control of exhaust
emissions, the PCM controls the spark advance of the
ignition system. Electronic ignition has the following
advantages over a mechanical distributor system:
No moving parts.
Less maintenance.
Remote mounting capability.
No mechanical load on the engine.
More coil cooldown time between firing events.
Elimination of mechanical timing adjustments.
Increased available ignition coil saturation time.
0013
Ignition Coils
A separate coil-at-plug module is located at each spark
plug. The coil-at-plug module is attached to the engine
with two screws. It is installed directly to the spark plug by
an electrical contact inside a rubber boot. A three-way
connector provides 12-volt primary supply from the
15-amp ignition fuse, a ground-switching trigger line from
the PCM, and a ground.
0001
Ignition Control
The ignition control (IC) spark timing is the PCM’s method
of controlling the spark advance and the ignition dwell.
The IC spark advance and the ignition dwell are
calculated by the PCM using the following inputs:
Engine speed.

6E–347 ENGINE DRIVEABILITY AND EMISSIONS
the secondary ignition circuit to flow through the spark
plug to the ground.
TS24047
Ignition Control PCM Output
The PCM provides a zero volt (actually about 100 mV to
200 mV) or a 5-volt output signal to the ignition control (IC)
module. Each spark plug has its own primary and
secondary coil module (”coil-at-plug”) located at the spark
plug itself. When the ignition coil receives the 5-volt signal
from the PCM, it provides a ground path for the B+ supply
to the primary side of the coil-at -plug module. This
energizes the primary coil and creates a magnetic field in
the coil-at-plug module. When the PCM shuts off the
5-volt signal to the ignition control module, the ground
path for the primary coil is broken. The magnetic field
collapses and induces a high voltage secondary impulse
which fires the spark plug and ignites the air/fuel mixture.
The circuit between the PCM and the ignition coil is
monitored for open circuits, shorts to voltage, and shorts
to ground. If the PCM detects one of these events, it will
set one of the following DTCs:
P0351: Ignition coil Fault on Cylinder #1
P0352: Ignition coil Fault on Cylinder #2
P0353: Ignition coil Fault on Cylinder #3
P0354: Ignition coil Fault on Cylinder #4
P0355: Ignition coil Fault on Cylinder #5
P0356: Ignition coil Fault on Cylinder #6
Knock Sensor (KS) PCM Input
The knock sensor (KS) system is comprised of a knock
sensor and the PCM. The PCM monitors the KS signals
to determine when engine detonation occurs. When a
knock sensor detects detonation, the PCM retards the
spark timing to reduce detonation. Timing may also be
retarded because of excessive mechanical engine or
transmission noise.
Powertrain Control Module (PCM)
The PCM is responsible for maintaining proper spark and
fuel injection timing for all driving conditions. To provideoptimum driveability and emissions, the PCM monitors
the input signals from the following components in order
to calculate spark timing:
Engine coolant temperature (ECT) sensor.
Intake air temperature (IAT) sensor.
Mass air flow (MAF) sensor.
PRNDL input from transmission range switch.
Throttle position (TP) sensor.
Vehicle speed sensor (VSS) .
Crankshaft position (CKP) sensor.
Spark Plug
Although worn or dirty spark plugs may give satisfactory
operation at idling speed, they frequency fail at higher
engine speeds. Faulty spark plugs may cause poor fuel
economy, power loss, loss of speed, hard starting and
generally poor engine performance. Follow the
scheduled maintenance service recommendations to
ensure satisfactory spark plug performance. Refer to
Maintenance and Lubrication.
Normal spark plug operation will result in brown to
grayish-tan deposits appearing on the insulator portion of
the spark plug. A small amount of red-brown, yellow, and
white powdery material may also be present on the
insulator tip around the center electrode. These deposits
are normal combustion by-products of fuels and
lubricating oils with additives. Some electrode wear will
also occur. Engines which are not running properly are
often referred to as “misfiring.” This means the ignition
spark is not igniting the air/fuel mixture at the proper time.
While other ignition and fuel system causes must also be
considered, possible causes include ignition system
conditions which allow the spark voltage to reach ground
in some other manner than by jumping across the air gap
at the tip of the spark plug, leaving the air/fuel mixture
unburned. Misfiring may also occur when the tip of the
spark plug becomes overheated and ignites the mixture
before the spark jumps. This is referred to as
“pre-ignition.”
Spark plugs may also misfire due to fouling, excessive
gap, or a cracked or broken insulator. If misfiring occurs
before the recommended replacement interval, locate
and correct the cause.
Carbon fouling of the spark plug is indicated by dry, black
carbon (soot) deposits on the portion of the spark plug in
the cylinder. Excessive idling and slow speeds under
light engine loads can keep the spark plug temperatures
so low that these deposits are not burned off. Very rich
fuel mixtures or poor ignition system output may also be
the cause. Refer to DTC P0172.
Oil fouling of the spark plug is indicated by wet oily
deposits on the portion of the spark plug in the cylinder,
usually with little electrode wear. This may be caused by
oil during break-in of new or newly overhauled engines.
Deposit fouling of the spark plug occurs when the normal
red-brown, yellow or white deposits of combustion by
products become sufficient to cause misfiring. In some
c a s e s , t h e s e d e p o s i t s m a y m e l t a n d f o r m a s h i n y g l a z e o n
the insulator around the center electrode. If the fouling is
found in only one or two cylinders, valve stem clearances
or intake valve seals may be allowing excess lubricating

6E–348
ENGINE DRIVEABILITY AND EMISSIONS
oil to enter the cylinder, particularly if the deposits are
heavier on the side of the spark plug facing the intake
valve.
TS23995
Excessive gap means that the air space between the
center and the side electrodes at the bottom of the spark
plug is too wide for consistent firing. This may be due to
improper gap adjustment or to excessive wear of the
electrode during use. A check of the gap size and
comparison to the gap specified for the vehicle in
Maintenance and Lubrication will tell if the gap is too wide.
A spark plug gap that is too small may cause an unstable
idle condition. Excessive gap wear can be an indication
of continuous operation at high speeds or with engine
loads, causing the spark to run too hot. Another possible
cause is an excessively lean fuel mixture.
TS23992
Low or high spark plug installation torque or improper
seating can result in the spark plug running too hot and
can cause excessive center electrode wear. The plug
and the cylinder head seats must be in good contact for
proper heat transfer and spark plug cooling. Dirty or
damaged threads in the head or on the spark plug cankeep it from seating even though the proper torque is
applied. Once spark plugs are properly seated, tighten
them to the torque shown in the Specifications Table. Low
torque may result in poor contact of the seats due to a
loose spark plug. Overtightening may cause the spark
plug shell to be stretched and will result in poor contact
between the seats. In extreme cases, exhaust blow-by
and damage beyond simple gap wear may occur.
Cracked or broken insulators may be the result of
improper installation, damage during spark plug
re-gapping, or heat shock to the insulator material. Upper
insulators can be broken when a poorly fitting tool is used
during installation or removal, when the spark plug is hit
from the outside, or is dropped on a hard surface. Cracks
in the upper insulator may be inside the shell and not
visible. Also, the breakage may not cause problems until
oil or moisture penetrates the crack later.
TS23994
A broken or cracked lower insulator tip (around the center
electrode) may result from damage during re-gapping or
from “heat shock” (spark plug suddenly operating too
hot).
TS23993