Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 708

6A–13

ENGINE MECHANICAL

Troubleshooting Procedure
The slapping sound stops when spark plug on bad
cylinder is shorted out.

Condition

Possible cause

Correction

Timing belt noise

Timing belt tension is incorrect

Replace pusher or adjust the tension
pulley or replace timing belt

Tensioner bearing defective

Replace

Timing belt defective

Replace

Timing pulley defective

Replace

Timing belt comes in contact with
timing cover

Replace timing belt and timing cover

Valve noise

Valve clearance incorrect

Replace adjusting shim

Valve and valve guide seized

Replace valve and valve guide

Valve spring broken or weakened

Replace

Valve seat off–positioned

Correct

Camshaft worn out

Replace

Crankshaft noise

Crankshaft end play excessive
(noise occurs when clutch is
engaged)

Replace thrust bearing

Engine knocking

Preignition due to use of spark plugs
of inadequate heat range

Install Spark Plugs of adequate heat
range

Carbon deposits in combustion
chambers

Clean

Fuel too low in octane rating

Replace fuel

Wide Open Throttle enrichment
system failure

Refer to Section 6E

Selection of transmission gear
incorrect

Caution operator of incorrect gear
selection

Engine overheating

Refer to “Engine Lacks Power”

Others

Water pump defective

Replace

Exhaust system defective

Repair or Replace

Drive belt slipping

Replace auto tentioner or drive belt

6A–14

ENGINE MECHANICAL

Abnormal Combustion

Condition

Possible cause

Correction

Trouble in fuel system

Fuel pressure control valve defective

Replace

Fuel filter clogged

Replace

Fuel pump clogged

Clean or replace

Fuel tank or fuel pipe clogged

Clean or replace

Fuel injector clogged

Clean or replace

Fuel pump relay defective

Replace

Power supply cable for fuel pump
broken or poor connections

Reconnect, correct or replace

Mass Airflow (MAF) sensor circuit
open or defective

Correct or replace

MAF Sensor defective

Replace

Manifold Absolute Pressure Sensor
circuit open or shorted

Correct or replace

Manifold Absolute Pressure Sensor
defective

Replace

Engine Coolant Temperature (ECT)
Sensor circuit open or shorted

Correct or replace

ECT Sensor defective

Replace

Throttle Position Sensor adjustment
incorrect

Readjust

Throttle Position Sensor defective

Replace

Throttle Position Sensor connector
poor connections

Reconnect

Vehicle Speed Sensor cable poor
connections or defective

Correct or replace

Vehicle Speed Sensor loosely fixed

Fix tightly

Vehicle Speed Sensor in wrong
contact or defective

Replace

Powertrain  Control Module cable
poor connections or defective

Correct or replace

Trouble in emission control system

Heated Oxygen Sensor circuit open

Correct or replace

Heated Oxygen Sensor defective

Replace

Signal vacuum hose loosely fitted or
defective

Correct or replace

EGR Valve circuit open or shorted

Correct or replace

Exhaust Gas Recirculation Valve
defective

Replace

ECT Sensor circuit open or shorted

Correct or replace

Canister Purge Valve circuit open or
shorted

Correct or replace

Canister Purge Valve defective

Replace

ECT Sensor defective

Replace

Positive Crankcase Ventilation
(PCV) valve and hose clogged

Correct or replace

Evaporator system

Refer to Section 6E

Trouble in ignition system

————

Refer to “Engine Lacks Power”

6A–15

ENGINE MECHANICAL

Condition

Correction

Possible cause

Trouble in cylinder head parts

Carbon deposits in combustion
chamber

Remove carbon

Carbon deposit on valve, valve seat
and valve guide

Remove carbon

6A–16

ENGINE MECHANICAL

Engine Oil Consumption Excessive

Condition

Possible cause

Correction

Oil leaking

Oil pan drain plug loose

Retighten or replace gasket

Crankcase fixing bolts loosened

Retighten

Oil pan setting bolts loosened

Retighten

Oil pan gasket broken

Replace gasket

Front cover retaining bolts loose or
gasket broken

Retighten or replace gasket

Head cover fixing  bolts loose or
gasket broken

Retighten or replace gasket

Oil filter adapter cracked

Replace

Oil filter attaching bolt loose or rubber
gasket broken

Retighten or replace oil filter

Crankshaft front or rear oil seal
defective

Replace oil seal

Oil pressure unit loose or broken

Retighten or replace

Blow–by gas hose broken

Replace hose

Positive Crankcase Ventilation Valve
clogged

Clean

Engine/Transmission coupling failed

Replace oil seal

Oil leaking into combustion

Valve stem oil seal defective

Replace

chambers due to poor seal in valve
system

Valve stem or valve guide worn

Replace valve and valve guide

Oil leaking into combustion
chambers due to poor seal in cylinder

Cylinders and pistons worn
excessively

Replace cylinder body assembly and
pistons

parts

Piston ring gaps incorrectly
positioned

Correct

Piston rings set with wrong side up

Correct

Piston ring sticking

Replace cylinder body assembly and
pistons

Piston ring and ring groove worn

Replace pistons and others

Return ports in oil rings clogged

Clean piston and replace rings

Positive Crankcase Ventilation
System malfunctioning

Positive Crankcase Ventilation Valve
clogged

Clean

Others

Improper oil viscosity

Use oil of recommended S.A.E.
viscosity

Continuous high speed driving
and/or severe usage such as trailer
towing

Continuous high speed operation
and/or severe usage will normally
cause increased oil consumption