power ISUZU TF SERIES 2004 Workshop Manual

6E–396 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
LACK OF POWER, SLUGGISH OR SPONGY SYMPTOM
DEFINITIONS: Engine delivers less than ex pected power. Attempting part-throttle acceleration results in little or no
increase in vehicle speed.
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. 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?—Verify repair Go to Step 3
3 Was a visually/physical check performed?
—Go to Step 4Go to Visual /
physical Check
4 Is the customer using the incorrect fuel type? Diesel fuel
onlyReplace with
diesel fuel Go to Step 5
5 Visually/physically inspect for the following conditions.
Restrict air intake system. Check for a restricted air
filter element, or foreign objects blocking the air
intake system
Check for objects blocking or ex cessive deposits in
the throttle bore and on the throttle plate
Check for a condition that causes a large vacuum
leak, such as an incorrectly installed or faulty
crankcase ventilation hose.
Restrict air intake system at the turbocharger.
Check for objects blocking the turbocharger
compressor wheel or turbine shaft sticking.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 6
6 Check the ECM & PSG grounds to verify that they are
clean and tight. Refer to the ECM wiring diagrams.
Was a problem found?—Verify repair Go to Step 7
7 1. Using the Tech 2, display the ECT sensor and IAT
sensor value.
2. Check the displayed value.
Does the Tech 2 indicate correct temperature
depending on engine condition?
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 8
8 1. Using the Tech 2, display the FT sensor value.
2. Check the displayed value.
Does the Tech 2 indicate correct temperature
depending on engine condition?
If a problem is found, repair as necessary.
Was the problem found?—Go to Step 29Go to Step 9
9 1. Using the Tech 2, ignition “On” and engine “Run”.
2. Monitor the “Mass Air Flow” in the data display.
Does the Tech 2 indicate correct “Mass Air Flow”
depending on accelerator pedal operation? —Go to Step 14Go to Step 10

6F – 16 EXHAUST SYSTEM
GENERAL DESCRIPTION



036LV002

The turbocharger internal mechanism consists of the turbine wheel, the compressor wheel, and the radial bearings.
These parts are supported by the bearing housing.
The turbocharger external mechanism consists of the compressor housing air intake port and the turbine housing
air exhaust port.
The turbocharger increases air intake efficiency. This results in increased engine power, reduced fuel consumption,
and minimal engine noise.
The turbocharger operates at very high speeds and temperatures. Part materials have been carefully selected and
machined to extremely high precision.
Turbocharger servicing requires great care and expertise.
If reduced performance is noted, check the engine for damage or wear. If there is no apparent engine damage or
wear, trouble with the turbocharger is indicated.

ENGINE MECHANICAL (6VE1 3.5L) 6A-7
Rough Engine Running
Symptom Possible Cause Action
Engine misfires periodically Ignition coil layer shorted Replace
Spark plugs fouling Clean or install hotter type plug
Spark plug(s) insulator nose leaking Replace
Fuel injector(s) defective Replace
Engine control module faulty Replace
Engine knocks periodically Spark plugs running too hot Install colder type spark plugs
Engine control module faulty Replace
Engine lacks power Spark plugs fouled Clean
Fuel injectors defective Replace
Mass Airflow Sensor or Intake Airflow
Sensor circuit defective Correct or replace
Engine Coolant Temperature Sensor
or Engine Coolant Temperature
Sensor circuit defective Correct or replace
Engine Control Module faulty Replace
Intake Air Temperature Sensor or
Intake Air Temperature Sensor circuit
defective Correct or replace
Throttle Position Sensor or Throttle
Position Sensor circuit defective Correct or replace

6A-8 ENGINE MECHANICAL (6VE1 3.5L)
Hesitation
Symptom Possible Cause Action
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 linkageAdjust or replace
Mass Airflow Sensor circuit open or
poor connections Correct or replace
Mass Airflow 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 pressure too low) Fuel tank strainer clogged Clean or replace
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

ENGINE MECHANICAL (6VE1 3.5L) 6A-9
Symptom Possible Cause Action
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
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-10 ENGINE MECHANICAL (6VE1 3.5L)
Engine Lacks Power
Symptom Possible Cause Action
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
Exhaust system clogged Correct or replace
Ignition failure ———— Refer to Hard Start Troubleshooting
Guide
Heat range of spark plug inadequateInstall spark plugs of adequate heat
range
Ignition coil defective Replace

6A-14 ENGINE MECHANICAL (6VE1 3.5L)
Troubleshooting Procedure
The slapping sound stops when spark plug on bad
cylinder is shorted out.

Symptom Possible Cause Action
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
Drive belt slipping Replace auto tentioner or drive belt

ENGINE MECHANICAL (6VE1 3.5L) 6A-15
Abnormal Combustion
Symptom Possible Cause Action
Trouble in fuel system Fuel pressure control valve defectiveReplace
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
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
Engine Control Module cable poor
connections or defective Correct or replace

6A-16 ENGINE MECHANICAL (6VE1 3.5L)
Symptom Possible Cause Action
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
EGR 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"
Trouble in cylinder head parts Carbon deposits in combustion
chamber Remove carbon
Carbon deposit on valve, valve seat
and valve guide Remove carbon

6A-28 ENGINE MECHANICAL (6VE1 3.5L)
Crankshaft Pulley
Removal
1. Disconnect battery ground cable.
2. Remove air cleaner assembly.
3. Remove radiator upper fan shroud from radiator.
4. Move serpentine belt tensioner to loose side using
wrench then remove serpentine belt.


850RW001
Legend
(1) Crankshaft Pulley
(2) Cooling Fan Pulley
(3) Tensioner
(4) Generator
(5) Air Conditioner Compressor
(6) Power Steering Oil Pump
(7) Serpentine Belt

5. Remove cooling fan assembly four fixing nuts,
then the cooling fan assembly.
6. Remove crankshaft pulley assembly using
5884001330 crankshaft holder, hold crankshaf
t
pulley then remove center bolt and pulley.
Installation
1. Install crankshaft pulley using 5884001330
crankshaft holder, hold the crankshaft pulley and
tighten center bolt to the specified torque.
Torque: 167 N




m (17.0 kg




m/123 lb ft)
2. Install cooling fan assembly and tighten bolts/nuts
to the specified torque.
Torque: 25 N




m (2.5 kg




m/18 lb ft) for fan pulley
and fan bracket.
Torque: 10 N




m (1.0 kg




m/88.5 lb in) for fan and
clutch assembly.
3. Move serpentine belt tensioner to loose side using
wrench, then install serpentine belt to normal
position.
4. Install radiator upper fan shroud.
5. Install air cleaner assembly.