spark plugs replace ISUZU AXIOM 2002 Service User Guide

6E±258
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0300 ± Engine Misfire Detected

 
StepNo Ye s Value(s) Action
81. Install a spark tester at the spark plug end of the
ignition coil for a cylinder that indicated a misfire.
2. Crank the engine while observing the spark tester.
A crisp, blue spark should be observed.
Is adequate spark present?
ÐGo to Step 14Go to Step 9
91. Remove and visually/physically inspect the ignition
coil(s) associated with the cylinders that were
indicated as misfiring. Ensure that the coil(s) are
free of cracks.
2. If a problem is found, replace the damaged ignition
coil(s) as necessary.
Did any ignition coils require replacement?
ÐVerify repairGo to Step 10
101. Remove the spark plugs from the cylinders that
were indicated as misfiring.
2. Visually inspect the spark plug electrodes.
Does your inspection reveal any spark plugs exhibiting
excessive fouling?
Ð
Go to Engine
Mechanical
Diagnosis
Go to Step 11
111. Visually inspect the spark plug insulators for cracks,
carbon tracking, or other damage.
2. If a problem is found, replace the faulty spark
plug(s) as necessary.
Did your inspection reveal a problem?
ÐVerify repairGo to Step 12
121. Disconnect the MAF sensor electrical connector.
2. Operate the vehicle in ªclosed loopº while
monitoring the ªBANK 1 L.T. FUEL TRIMº and
ªBANK 1 S.T. FUEL TRIMº display on the Tech 2.
Do both values decrease below the specified values?ºBANK 1 L.T.
FUEL TRIMº
below +20%;
ªBANK 1 S.T.
FUEL TRIMº
below +50%
Go to Step 13
Replace the
ignition coil of
the affected
cylinder
13Replace the ignition coil control module.
Is the action complete?
ÐVerify repairÐ
141. Visually and physically inspect the PCM injector
grounds, power grounds and sensor grounds to
ensure that they are clean, tight and in their proper
locations.
2. If a problem is found, correct the faulty ground
condition as necessary.
Did your inspection reveal a poor ground?
ÐVerify repair Go to Step 15
151. Perform the ªFuel System Pressure Testº
procedure.
2. If a problem is found, repair as necessary (refer to
Engine Fuel or Fuel Metering System).
Was a fuel system problem found?
ÐVerify repairGo to Step 16
161. Check the fuel for excessive water, alcohol, or other
contaminants (refer to
Diagnosis in Engine Fuel for
procedure).
2. If a problem is found, correct the contaminated fuel
condition as necessary.
Was the fuel contaminated?
ÐVerify repairGo to Step 17

6E±508
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Hard Start Symptom

 
StepNo Ye s Value(s) Action
121. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electric Ignition
System
for procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 13
131. Remove spark plugs. Check for wet plugs, cracks,
wear, improper gap, burned electrodes, or heavy
deposits. Refer to
Electronic Ignition System.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 14
141. Check for a loose ignition coil ground and ION
Sensing module circuit.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 15
151. Remove the ignition coils and check the ignition
coils for cracks or carbon tracking.
2. If a problem is found, replace affected coil(s) as
necessary.
Was a problem found?
ÐVerify repairGo to Step 16
161. Check for the following engine mechanical
problems (refer to
Engine Mechanical):

Low compression

Leaking cylinder head gaskets

Worn or incorrect camshaft

Camshaft drive belt slipped or stripped
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 17
171. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records buffer

All electrical connections within a suspected
circuit and/or system.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Contact
Technical
Assistance

6E±510
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Surges and/or Chuggles Symptom

 
StepNo Ye s Value(s) Action
101. Check items that can cause the engine to run lean.
Refer to
Diagnostic Aids in DTC P0171.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 11Verify repair
111. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electric Ignition
System
for procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 12
121. Check for a loose ignition coil ground and ION
Sensing module circuit.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 13
131. Check the ignition coils for cracks or carbon
tracking.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 15
141. Remove the spark plugs and check for wet plugs,
cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to
Electronic Ignition
System
.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 15
151. Check the injector connections.
2. If any of the injector connectors are connected to an
incorrect cylinder, correct as necessary.
Was a problem found?
ÐVerify repairGo to Step 16
161. Check PCM grounds for the cleanliness, tightness
and proper locations. Refer to the PCM wiring
diagrams in
Electrical Diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 17
171. Check MAF sensor connections.
2. If a problem is found, replace the faulty terminals as
necessary. Refer to
Electrical Diagnosis for wiring
repair procedures.
Was a problem found?
ÐVerify repairGo to Step 18
181. Visually/physically check vacuum hoses for splits,
kinks, and proper connections and routing as
shown on the ªVehicle Emission Control
Informationº label.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 19

6E±515
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Detonation/Sparks Knock Symptoms

 
StepNo Ye s Value(s) Action
101. Disconnect the ignition coil.
Is the action complete?
ÐGo to Step 11Ð
11Check the ION sensing harness between the ignition
coil and ION sensing module circuit at the DC motor
harness connector.
Was a problem found?
ÐVerify repairGo to Step 12
12Check the following items;
1. Ignition coil and ignition coil circuit.
2. Ignition coil ground circuit for a poor connection.
3. If a problem is found, repair wiring harness as
necessary.
Was a problem found?
ÐVerify repairGo to Step 13
13Replace the Ignition coil.
Is the action complete?
ÐVerify repairGo to Step 14
14Check the following items;
1. ION sensing module ground circuit for a poor
connection.
2. If a problem is found, repair wiring harness as
necessary.
Was a problem found?
ÐGo to Step 10Go to Step 16
15Replace the ION sensing module.
Is the action complete?
ÐVerify repairGo to Step 16
161. Check fuel pressure. Refer to Chart Fuel System
Pressure Test.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Go to Step
17
171. Check items that can cause an engine to run lean
(long term fuel trim significantly in the positive
range). For a lean condition, refer to
Diagnostic
Aids
in DTC P0171 Diagnostic Support.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 18
181. Spark plugs for proper heat range. Refer to General
Information
.
2. If incorrect spark plugs are installed, replace spark
plugs as necessary.
Did any spark plugs require replacement?
ÐVerify repairGo to Step 19
191. Remove excessive carbon buildup with a top engine
cleaner. Refer to instructions on the top engine
cleaner can.
2. Re-evaluate vehicle performance.
Is detonation still present?
ÐGo to Step 20Verify repair

6E±518
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Rough, Unstable, or Incorrect Idle, Stalling Symptom

 
StepNo Ye s Value(s) Action
111. Visually/physically inspect for the following
conditions:

Restricted air intake system. Check for a
possible collapsed air intake duct, restricted
air filter element, or foreign objects blocking
the air intake system.

Large vacuum leak. Check for a condition that
causes a large vacuum leak, such as an
incorrectly installed or faulty crankcase
ventilation valve or a disconnected brake
booster hose.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
12Check the injector connections. If any of the injectors
are connected to an incorrect cylinder, correct as
necessary.
Was a problem found?
ÐVerify repairGo to Step 13
131. Perform the ªInjector Coil/Balance Testº in Fuel
Metering System
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 14
141. Check for fuel in the pressure regulator vacuum
hose.
2. If fuel is present, replace the fuel pressure regulator
assembly. Refer to
Fuel Metering System.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 15
151. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electronic Ignition
System
for the procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 16
161. Remove spark plugs. Check for wet plugs, cracks,
wear, improper gap, burned electrodes, or heavy
deposits. Refer to
Electronic Ignition System.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 17
171. Check for a loose ignition coil ground and ION
Sensing Module circuit.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 18
181. Check ignition coils for cracks or carbon tracking.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 19

6E±520
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Poor Fuel Economy Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Fuel economy, as measured by an actual road test, is
noticeably lower than expected. Also, economy is
noticeably lower than it was on this vehicle at one time,
as previously shown by an actual road test.
(Non-standard tires will cause odometer readings to be
incorrect, and that may cause fuel economy to appear
poor when it is actually normal.)
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to Visual/
Physical
Check
4Check owner's driving habits.

Is the A/C ªONº full time (defroster mode ªONº)?

Are tires at the correct pressure?

Are excessively heavy loads being carried?

Is acceleration too much, too often?
Was a problem found?
ÐGo to Step 5Go to Step 6
5Review the items in Step 4 with the customer and
advise as necessary.
Is the action complete?
ÐSystem OKÐ
61. Visually/physically check: Vacuum hoses for splits,
kinks, and improper connections and routing as
shown on the ªVehicle Emission Control
Informationº label.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Remove and check the air filter element for dirt or for
restrictions. Refer to
Air Intake System.
2. Replace the air filter element if necessary.
Was a repair required?
ÐVerify repairGo to Step 8
81. Remove spark plugs and check for wet plugs,
cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to
Spark Plug Replacement.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
91. Check for low engine coolant level. Refer to Engine
Cooling
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 10

6E±528
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Cuts Out, Misses Symptom

 
StepNo Ye s Value(s) Action
111. Visually/physically inspect for the following
conditions:

Restricted air intake system. Check for a
possible collapsed air intake duct, restricted
air filter element, or foreign objects blocking
the air intake system.

Large vacuum leak. Check for a condition that
causes a large vacuum leak, such as an
incorrectly installed or faulty PCV valve or
brake booster hose disconnected .
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
12Check the injector connections. If any of the injectors
are connected to an incorrect cylinder, correct as
necessary.
Was a problem found?
ÐVerify repairGo to Step 13
131. Perform the ªInjector Coil/Balance Testº in Fuel
Metering System
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 14
141. Check for fuel in the pressure regulator vacuum
hose.
2. If fuel is present, replace the fuel pressure regulator
assembly. Refer to
Fuel Metering System.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 15
151. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electronic Ignition
System
for the procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 16
161. Remove spark plugs. Check for wet plugs, cracks,
wear, improper gap, burned electrodes, or heavy
deposits. Refer to
Electronic Ignition System.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 17
171. Check for a loose ignition coil ground and ION
Sensing module circuit.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 18
181. Check ignition coils for cracks or carbon tracking.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 19
19Using a Tech 2, monitor the TP 1, 2 angle with the
engine idling.
Is the TP angle at the specified value and steady?
8 ~ 10%Go to Step 20
Refer to DTC
P0123
for
further
diagnosis

6E±531
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Hesitation, Sag, Stumble Symptom

 
StepNo Ye s Value(s) Action
101. Check items that can cause the engine to run lean.
Refer to
Diagnostic Aids in DTC P0171 Diagnostic
Support
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 11
111. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electronic Ignition
System
for the procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 12
121. Check for a loose ignition coil ground and ION
Sensing module circuit.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 13
131. Check the ignition coils for cracks or carbon
tracking.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 14
141. Remove spark plugs and check for wet plugs,
cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to
Electronic Ignition
System
.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 15
151. Check the PCM grounds for clearness, tightness
and proper routing. Refer to the PCM wiring
diagrams in Electrical Diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 16
161. Check the MAF sensor connections.
2. If a problem is found, replace the faulty terminals as
necessary. Refer to
Electrical Diagnosis for wiring
repair procedures.
Was a problem found?
ÐVerify repairGo to Step 17

6E±582
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

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 section.
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 ªmisfiring.º 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. Refer to
DTC P0300. 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 ªpre-ignition.º
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
cases, these deposits may melt and form a shiny glaze on
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
oil to enter the cylinder, particularly if the deposits are
heavier on the side of the spark plug facing the intake
valve.
TS23995Excessive 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 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.
TS23992Low 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 can
keep 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