engine ISUZU AXIOM 2002 Service Repair Manual

6A±7
ENGINE MECHANICAL (6VE1 3.5L)
Rough Engine Running
ConditionPossible causeCorrection
Engine misfires periodicallyIgnition coil layer shortedReplace
Spark plugs foulingClean or install hotter type plug
Spark plug(s) insulator nose leakingReplace
Fuel injector(s) defectiveReplace
Powertrain control module faultyReplace
Engine knocks periodicallySpark plugs running too hotInstall colder type spark plugs
Powertrain control module faultyReplace
Ion Sensing module faultyRefer or replace
Engine lacks powerSpark plugs fouledClean
Fuel injectors defectiveReplace
Mass Airflow Sensor or Intake
Airflow Sensor circuit defectiveCorrect or replace
Manifold Absolute Pressure (MAP)
Sensor or Manifold Absolute
Pressure Sensor circuit defectiveCorrect or replace
Engine Coolant Temperature Sensor
or Engine Coolant Temperature
Sensor circuit defectiveCorrect or replace
Powertrain Control Module faultyReplace
Intake Air Temperature Sensor or
Intake Air Temperature Sensor
circuit defectiveCorrect or replace
Throttle Position Sensor or Throttle
Position Sensor circuit defectiveCorrect or replace
ION Sensing Module or ION Sensing
Module circuits defectiveCorrect or replace

6A±8
ENGINE MECHANICAL (6VE1 3.5L)
Hesitation
ConditionPossible causeCorrection
Hesitation on accelerationThrottle Position Sensor adjustment
incorrectReplace throttle valve assembly
Throttle Position Sensor circuit open
or shortedCorrect or replace
Mass Airflow Sensor circuit open or
poor connectionsCorrect or replace
Mass Airflow Sensor defectiveReplace
Manifold Absolute Pressure (MAP)
Sensor circuit open or shortedCorrect or replace
MAP Sensor defectiveReplace
Intake Air Temperature (IAT) Sensor
circuit open or poor connectionsCorrect or replace
Ion Sensing Module circuit open or
poor connectionsCorrect or replace
Ion Sensing Module defectiveReplace
IAT Sensor defectiveReplace
Hesitation at high speedsFuel tank strainer cloggedClean or replace
(Fuel pressure too low)Fuel pipe cloggedClean or replace
Fuel filter cloggedReplace
Defective fuel pump systemCheck and replace
Fuel Pressure Control Valve leakingReplace
Hesitation at high speeds
(Fuel injector not working normally)Power supply or ground circuit for
Multiport Fuel Injection System
shorted or openCheck and correct or replace
Fuel Injector defectiveReplace
Cable of Multiport Fuel Injection
System circuit open or poor
connectionsCorrect or replace

6A±9
ENGINE MECHANICAL (6VE1 3.5L)
Condition CorrectionPossible cause
Hesitation at high speedsPowertrain Control Module defectiveReplace
Throttle Position Sensor cable
broken or poor connectionsCorrect or replace
Throttle Position Sensor defectiveReplace
Engine Coolant Temperature Sensor
circuit open or shortedCorrect or replace
Engine Coolant Temperature Sensor
defectiveReplace
Mass Airflow Sensor circuit open or
poor connectionsCorrect or replace
Mass Airflow Sensor defectiveReplace
MAP Sensor cable broken or poor
connectionsCorrect or replace
MAP Sensor defectiveReplace
IAT Sensor circuit open or poor
connectionsCorrect or replace
IAT Sensor defectiveReplace
Ion Sensing Module circuit open or
poor connectionsCorrect or replace
Ion Sensing Module defectiveReplace
Throttle valve not fully openedCheck and correct or replace
Air Cleaner Filter cloggedReplace filter element
Power supply voltage too lowCheck and correct or replace

6A±10
ENGINE MECHANICAL (6VE1 3.5L)
Engine Lacks Power
ConditionPossible causeCorrection
Trouble in fuel systemFuel Pressure Control Valve not
working normallyReplace
Fuel injector cloggedClean or replace
Fuel pipe cloggedClean
Fuel filter clogged or fouledReplace
Fuel pump drive circuit not working
normallyCorrect or replace
Fuel tank not sufficiently breathing
due to clogged Evaporative
Emission Control System circuitClean or replace
Water in fuel systemClean
Inferior quality fuel in fuel systemUse fuel of specified octane rating
Powertrain Control Module supplied
poor voltageCorrect circuit
Throttle Position Sensor cable
broken or poor connectionsCorrect or replace
Throttle Position Sensor defectiveReplace
Mass Airflow Sensor not working
normallyReplace
Manifold Absolute Pressure Sensor
not working normallyReplace
Intake Air Temperature Sensor not
working normallyReplace
Engine Coolant Temperature Sensor
circuit open or shortedCorrect or replace
Engine Coolant Temperature Sensor
defectiveReplace
Powertrain Control Module defectiveReplace
Trouble in intake or exhaust systemAir Cleaner Filter cloggedReplace filter element
Air duct kinked or flattenedCorrect or replace
TWC defectiveRepair
Ignition failureÐÐÐÐRefer to Hard Start Troubleshooting
Guide
Heat range of spark plug inadequateInstall spark plugs of adequate heat
range
Ignition coil defectiveReplace

6A±11
ENGINE MECHANICAL (6VE1 3.5L)
Condition CorrectionPossible cause
Engine overheatingLevel of Engine Coolant too lowReplenish
Fan clutch defectiveReplace
Incorrect fan installedReplace
Thermostat defectiveReplace
Engine Coolant pump defectiveCorrect or replace
Radiator cloggedClean or replace
Radiator filler cap defectiveReplace
Level of oil in engine crankcase too
low or wrong engine oilChange or replenish
Resistance in exhaust system
increasedClean exhaust system or replace
defective parts
Throttle Position Sensor adjustment
incorrectReplace with Throttle Valve ASM
Throttle Position Sensor circuit open
or shortedCorrect or replace
Cylinder head gasket damagedReplace
Engine overcoolingThermostat defectiveReplace (Use a thermostat set to
open at 82
C (180
F))
Engine lacks compressionÐÐÐÐRefer to Hard Start
OthersTire inflation pressure abnormalAdjust to recommended pressures
Brake dragAdjust
Clutch slippingAdjust or replace
Level of oil in engine crankcase too
highCorrect level of engine oil
Exhaust Gas Recirculation Valve
defectiveReplace

6A±12
ENGINE MECHANICAL (6VE1 3.5L)
Engine Noisy
Abnormal engine noise often consists of various noises
originating in rotating parts, sliding parts and other
moving parts of the engine. It is, therefore, advisable to
locate the source of noise systematically.
Troubleshooting Procedure for Crankshaft Journals or Crankshaft Bearing Noise
Condition
Possible causeCorrection
Noise from crank journals or from
crank bearings
(Faulty crank journals and crankOil clearance increased due to worn
crank journals or crank bearingsReplace crank bearings and
crankshaft or regrind crankshaft and
install the undersize bearing
yj
bearings usually make dull noise that
becomes more evident when
accelerating)Crankshaft out of roundReplace crank bearings and
crankshaft or regrind crankshaft and
install the undersize bearing
Crank bearing seizedCrank bearing seized Replace crank
bearings and crankshaft or regrind
crankshaft and install the undersize
bearing
Troubleshooting Procedure for Connecting Rods or Connecting Rod Bearing Noise
Short out each spark plug in sequence using insulated
spark plug wire removers. Locate cylinder with defective
bearing by listening for abnormal noise that stops when
spark plug is shorted out.
Condition
Possible causeCorrection
Noise from connecting rods or from
connecting rod bearings
(Faulty connecting rods orBearing or crankshaft pin wornReplace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
yg
connecting rod bearings usually
make an abnormal noise slightly
higher than the crank bearing noise,
which becomes more evident when
Crankpin out of roundReplace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
which becomes more evident when
engine is accelerated)Connecting rod bentCorrect or replaceg)
Connecting rod bearing seizedReplace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
Troubleshooting Procedure for Piston and Cylinder Noise
Abnormal noise stops when the spark plug on the cylinder
with defective part is shorted out.
Condition
Possible causeCorrection
Piston and cylinder noise
(Faulty piston or cylinder usually
k bid hil
Piston clearance increased due to
cylinder wearReplace piston and cylinder body
makes a combined mechanical
thumping noise which increasesPiston seizedReplace piston and cylinder bodyg
when engine is suddenly accelerated
but diminishes
gradually as thePiston ring brokenReplace piston and cylinder bodybut diminishes gradually as the
engine warms up)Piston defectiveReplace pistons and others
Troubleshooting Procedure for Piston Pin Noise
Short out each spark plug and listen for change in engine
noise.
Condition
Possible causeCorrection
Piston pin noise
(Piston makes noise each time it
goes up and down)Piston pin or piston pin hole wornReplace piston, piston pin and
connecting rod assy

6A±13
ENGINE MECHANICAL (6VE1 3.5L)
Troubleshooting Procedure for Slapping or Hitting etc Noise
The slapping sound stops when spark plug on bad
cylinder is shorted out.
Condition
Possible causeCorrection
Timing belt noiseTiming belt tension is incorrectReplace pusher or adjust the tension
pulley or replace timing belt
Tensioner bearing defectiveReplace
Timing belt defectiveReplace
Timing pulley defectiveReplace
Timing belt comes in contact with
timing coverReplace timing belt and timing cover
Valve noiseValve clearance incorrectReplace adjusting shim
Valve and valve guide seizedReplace valve and valve guide
Valve spring broken or weakenedReplace
Valve seat off±positionedCorrect
Camshaft worn outReplace
Crankshaft noiseCrankshaft end play excessive
(noise occurs when clutch is
engaged)Replace thrust bearing
Engine knockingPreignition due to use of spark plugs
of inadequate heat rangeInstall Spark Plugs of adequate heat
range
Carbon deposits in combustion
chambersClean
Fuel too low in octane ratingReplace fuel
Wide Open Throttle enrichment
system failureRefer to Section 6E
Selection of transmission gear
incorrectCaution operator of incorrect gear
selection
Engine overheatingRefer to ªEngine Lacks Powerº
OthersWater pump defectiveReplace
Drive belt slippingReplace auto tensioner or drive belt

6A±14
ENGINE MECHANICAL (6VE1 3.5L)
Abnormal Combustion
ConditionPossible causeCorrection
Trouble in fuel systemFuel pressure control valve defectiveReplace
Fuel filter cloggedReplace
Fuel pump cloggedClean or replace
Fuel tank or fuel pipe cloggedClean or replace
Fuel injector cloggedClean or replace
Fuel pump relay defectiveReplace
Power supply cable for fuel pump
broken or poor connectionsReconnect, correct or replace
Mass Airflow (MAF) Sensor circuit
open or defectiveCorrect or replace
MAF Sensor defectiveReplace
Manifold Absolute Pressure Sensor
circuit open or shortedCorrect or replace
Manifold Absolute Pressure Sensor
defectiveReplace
Engine Coolant Temperature (ECT)
Sensor circuit open or shortedCorrect or replace
ECT Sensor defectiveReplace
Throttle Position Sensor adjustment
incorrectReadjust
Throttle Position Sensor defectiveReplace
Throttle Position Sensor connector
poor connectionsReconnect
Vehicle Speed Sensor cable poor
connections or defectiveCorrect or replace
Vehicle Speed Sensor loosely fixedFix tightly
Vehicle Speed Sensor in wrong
contact or defectiveReplace
Powertrain Control Module cable
poor connections or defectiveCorrect or replace
Trouble in emission control systemHeated Oxygen Sensor circuit openCorrect or replace
Heated Oxygen Sensor defectiveReplace
Signal vacuum hose loosely fitted or
defectiveCorrect or replace
EGR Valve circuit open or shortedCorrect or replace
Exhaust Gas Recirculation Valve
defectiveReplace
ECT Sensor circuit open or shortedCorrect or replace
Canister Purge Valve circuit open or
shortedCorrect or replace
Canister Purge Valve defectiveReplace
ECT Sensor defectiveReplace
Positive Crankcase Ventilation
(PCV) valve and hose cloggedCorrect or replace
Evaporator systemRefer to Section 6E
Trouble in ignition systemÐÐÐÐRefer to ªEngine Lacks Powerº

6A±15
ENGINE MECHANICAL (6VE1 3.5L)
Condition CorrectionPossible cause
Trouble in cylinder head partsCarbon deposits in combustion
chamberRemove carbon
Carbon deposit on valve, valve seat
and valve guideRemove carbon

6A±16
ENGINE MECHANICAL (6VE1 3.5L)
Engine Oil Consumption Excessive
ConditionPossible causeCorrection
Oil leakingOil pan drain plug looseRetighten or replace gasket
Crankcase fixing bolts loosenedRetighten
Oil pan setting bolts loosenedRetighten
Oil pan gasket brokenReplace gasket
Front cover retaining bolts loose or
gasket brokenRetighten or replace gasket
Head cover fixing bolts loose or
gasket brokenRetighten or replace gasket
Oil filter adapter crackedReplace
Oil filter attachings bolt loose or
rubber gasket brokenRetighten or replace oil filter
Crankshaft front or rear oil seal
defectiveReplace oil seal
Oil pressure unit loose or brokenRetighten or replace
Blow±by gas hose brokenReplace hose
Positive Crankcase Ventilation Valve
cloggedClean
Engine/Transmission coupling failedReplace oil seal
Oil leaking into combustion
chambers due topoor seal in valve
Valve stem oil seal defectiveReplace
chambers due to oor seal in valve
systemValve stem or valve guide wornReplace valve and valve guide
Oil leaking into combustion
chambers due to poor seal in cylinder
t
Cylinders and pistons worn
excessivelyReplace cylinder body assembly and
pistons
partsPiston ring gaps incorrectly
positionedCorrect
Piston rings set with wrong side upCorrect
Piston ring stickingReplace cylinder body assembly and
pistons
Piston ring and ring groove wornReplace pistons and others
Return ports in oil rings cloggedClean piston and replace rings
Positive Crankcase Ventilation
System malfunctioningPositive Crankcase Ventilation Valve
cloggedClean
OthersImproper oil viscosityUse oil of recommended S.A.E.
viscosity
Continuous high speed driving
and/or severe usage such as trailer
towingContinuous high speed operation
and/or severe usage will normally
cause increased oil consumption