Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Service manual — part 782
6A–8
ENGINE MECHANICAL (6VD1 3.2L)
Hesitation
Condition
Possible cause
Correction
Hesitation on acceleration
Throttle Position Sensor adjustment
incorrect
Replace throttle valve assembly
Throttle Position Sensor circuit open
or shorted
Correct or replace
Excessive play in accelerator linkage
Adjust or replace
Mass Airflow Sensor circuit open or
poor connections
Correct or replace
Mass Airflow Sensor defective
Replace
Barometric Pressure (BARO)
Sensor circuit open or shorted
Correct or replace
BARO Sensor defective
Replace
Intake Air Temperature (IAT) Sensor
circuit open or poor connections
Correct or replace
IAT Sensor defective
Replace
Hesitation at high speeds
Fuel tank strainer clogged
Clean or replace
(Fuel pressure too low)
Fuel pipe clogged
Clean or replace
Fuel filter clogged
Replace
Defective fuel pump system
Check and replace
Fuel Pressure Control Valve leaking
Replace
Hesitation at high speeds
(Fuel injector not working normally)
Power supply or ground circuit for
Multiport Fuel Injection System
shorted or open
Check and correct or replace
Fuel Injector defective
Replace
Cable of Multiport Fuel Injection
System circuit open or poor
connections
Correct or replace
Hesitation at high speeds
Engine Control Module defective
Replace
Throttle Position Sensor cable
broken or poor connections
Correct or replace
Throttle Position Sensor defective
Replace
Engine Coolant Temperature Sensor
circuit open or shorted
Correct or replace
Engine Coolant Temperature Sensor
defective
Replace
Mass Airflow Sensor circuit open or
poor connections
Correct or replace
Mass Airflow Sensor defective
Replace
MAP Sensor cable broken or poor
connections
Correct or replace
MAP Sensor defective
Replace
IAT Sensor circuit open or poor
connections
Correct or replace
IAT Sensor defective
Replace
Throttle valve not fully opened
Check and correct or replace
Air Cleaner Filter clogged
Replace filter element
Power supply voltage too low
Check and correct or replace
6A–9
ENGINE MECHANICAL (6VD1 3.2L)
Engine Lacks Power
Condition
Possible cause
Correction
Trouble in fuel system
Fuel Pressure Control Valve not
working normally
Replace
Fuel injector clogged
Clean or replace
Fuel pipe clogged
Clean
Fuel filter clogged or fouled
Replace
Fuel pump drive circuit not working
normally
Correct or replace
Fuel tank not sufficiently breathing
due to clogged Evaporative
Emission Control System circuit
Clean or replace
Water in fuel system
Clean
Inferior quality fuel in fuel system
Use fuel of specified octane rating
Engine Control Module supplied poor
voltage
Correct circuit
Throttle Position Sensor cable
broken or poor connections
Correct or replace
Throttle Position Sensor defective
Replace
Mass Airflow Sensor not working
normally
Replace
Manifold Absolute Pressure Sensor
not working normally
Replace
Intake Air Temperature Sensor not
working normally
Replace
Engine Coolant Temperature Sensor
circuit open or shorted
Correct or replace
Engine Coolant Temperature Sensor
defective
Replace
Engine Control Module defective
Replace
Trouble in intake or exhaust system
Air Cleaner Filter clogged
Replace filter element
Air duct kinked or flattened
Correct or replace
Ignition failure
————
Refer to Hard Start Troubleshooting
Guide
Heat range of spark plug inadequate
Install spark plugs of adequate heat
range
Ignition coil defective
Replace
6A–10
ENGINE MECHANICAL (6VD1 3.2L)
Condition
Correction
Possible cause
Engine overheating
Level of Engine Coolant too low
Replenish
Fan clutch defective
Replace
Thermostat defective
Replace
Engine Coolant pump defective
Correct or replace
Radiator clogged
Clean or replace
Radiator filler cap defective
Replace
Level of oil in engine crankcase too
low or wrong engine oil
Change or replenish
Resistance in exhaust system
increased
Clean exhaust system or replace
defective parts
Throttle Position Sensor adjustment
incorrect
Replace with Throttle Valve ASM
Throttle Position Sensor circuit open
or shorted
Correct or replace
Cylinder head gasket damaged
Replace
Engine overcooling
Thermostat defective
Replace (Use a thermostat set to
open at 82
°
C (180
°
F))
Engine lacks compression
————
Refer to Hard Start
Others
Tire inflation pressure abnormal
Adjust to recommended pressures
Brake drag
Adjust
Clutch slipping
Adjust or replace
Level of oil in engine crankcase too
high
Correct level of engine oil
6A–11
ENGINE MECHANICAL (6VD1 3.2L)
Engine Noisy
Abnormal engine noise often consists of various noises
originating in rotating parts, sliding parts and other mov-
ing parts of the engine. It is, therefore, advisable to locate
the source of noise systematically.
Condition
Possible cause
Correction
Noise from crank journals or from
crank bearings
(Faulty crank journals and crank
Oil clearance increased due to worn
crank journals or crank bearings
Replace crank bearings and
crankshaft or regrind crankshaft and
install the undersize bearing
y
j
bearings usually make dull noise that
becomes more evident when
accelerating)
Crankshaft out of round
Replace crank bearings and
crankshaft or regrind crankshaft and
install the undersize bearing
Crank bearing seized
Crank bearing seized Replace crank
bearings and crankshaft or regrind
crankshaft and install the undersize
bearing
Troubleshooting Procedure
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 cause
Correction
Noise from connecting rods or from
connecting rod bearings
(Faulty connecting rods or
Bearing or crankshaft pin worn
Replace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
y
g
connecting rod bearings usually
make an abnormal noise slightly
higher than the crank bearing noise,
which becomes more evident when
Crankpin out of round
Replace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
which becomes more evident when
engine is accelerated)
Connecting rod bent
Correct or replace
g
)
Connecting rod bearing seized
Replace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
Troubleshooting Procedure
Abnormal noise stops when the spark plug on the cylinder
with defective part is shorted out.
Condition
Possible cause
Correction
Piston and cylinder noise
(Faulty piston or cylinder usually
k
bi
d
h
i
l
Piston clearance increased due to
cylinder wear
Replace piston and cylinder body
makes a combined mechanical
thumping noise which increases
Piston seized
Replace piston and cylinder body
g
when engine is suddenly accelerated
but diminishes gradually as the
Piston ring broken
Replace piston and cylinder body
but diminishes gradually as the
engine warms up)
Piston defective
Replace pistons and others
Troubleshooting Procedure
Short out each spark plug and listen for change in engine
noise.
Condition
Possible cause
Correction
Piston pin noise
(Piston makes noise each time it
goes up and down)
Piston pin or piston pin hole worn
Replace piston, piston pin and
connecting rod assy
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