2004 ISUZU TF SERIES gas type

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–407
EXCESSIVE WHITE SMOKE
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 Check the engine coolant consumption to verify that it
leaks to combustion chamber or ex haust through the
gasket.
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 30Go 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
10 Remove the MAF & IAT sensor assembly and check
for the following conditions.
Objects blocking at the MAF sensor element.
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 11
11 Check the MAF sensor harness for the following
conditions.
Check for poor connector connection.
Check for misrouted harness.
Check for any accessory parts which may cause
electric interference.
If a problem is found, repair as necessary.
Was a problem found? —Verify repair Go to Step 12

6D1-2 ENGINE ELECTRICAL (6VE1 3.5L)
Battery
General Description
There are six battery fluid caps on the top of the battery.
These are covered by a paper label.
The battery is completely sealed except for the six small
vent holes on the side. These vent holes permit the
escape of small amounts of gas generated by the
battery.
This type of battery has the following advantages ove
r
conventional batteries:
1. There is no need to add water during the entire
service life of the battery.
2. The battery protects itself against overcharging.
The battery will refuse to accept an extensive
charge.
(A conventional battery will accept an excessive
charge, resulting in gassing and loss of battery
fluid.)
3. The battery is much less vulnerable to sel
f
discharge than a conventional type battery.
Diagnosis
1. Visual Inspection
Inspect the battery for obvious physical damage, such
as a cracked or broken case, which would permi
t
electrolyte loss.
Replace the battery if obvious physical damage is
discovered during inspection.
Check for any other physical damage and correct it as
necessary.


2. Fluid Level Check
The fluid level should be between the upper level line(1)
and lower level line(2) on side of battery.
a. CORRECT FLUID LEVEL – Charge the battery.
b. BELOW LOWER LEVEL – Replace battery.



RTW36DSH000101
3. Voltage Check
1. Put voltmeter test leads to battery terminals.
a. VOLTAGE IS 12.4V OR ABOVE – Go to Step 5.
b. VOLTAGE IS UNDER 12.4V – Go to procedure
(2) below.
2. Determine fast charge amperage from specification.
(See Main Data and Specifications in this section).
Fast charge battery for 30 minutes at amperage
rate no higher than specified value.
Take voltage and amperage readings after charge.
a. VOLTAGE IS ABOVE 16V AT BELOW 1/3 OF
AMPERAGE RATE – Replace battery.
b. VOLTAGE IS ABOVE 16V AT ABOVE 1/3 OF
AMPERAGE RATE – Drop charging voltage to
15V and charge for 10 – 15 hours. Then go to
Step 5.
c. VOLTAGE IS BETWEEN 12V AND 16V –
Continue charging at the same rate for an
additional 3–1/2 hours. Then go to Step 5.
d. VOLTAGE BELOW 12V – Replace Battery.

6D2-4 IGNITION SYSTEM (6VE1 3.5L)
Spark Plug
Inspection
Poor spark plug condition adversely affects engine
performance. Carefully inspect each spark plug
following the procedure outlined below.
1. Remove the spark plug.
2. Check the plug for dirt and other foreign material.
If the plug is extremely dirty, the fuel and electrical
systems must be checked.
3. If necessary, clean the spark plugs by placing them
in a spark plug cleaning machine for no more than
20 seconds.
4. Check the electrode and insulator for wear and/o
r
cracking. If there is significant wear or cracking, the
plug must be replaced.
5. Check the gasket for damage. Replace the gasket i
f
necessary.
6. Measure the insulation resistance with a 500-vol
t
megaohm meter. Replace the plug if the resistance
is less than the specified value.
Insulation resistance: 50 M





or more




011RS010

7. Check the spark plug gap. Replace the spark plug
the if gap is not as specified.
Standard: 1.0–1.1 mm (0.04–0.043 in)
Limit: 1.3 mm (0.05 in)





011RS011
 Do not attempt to adjust the gap of an old spark
plug. Replace the plug and adjust the gap of the
new plug if required.
 Take care not to damage the spark plug tip
during handling.
8. Tighten the spark plugs to the specified torque.
Torque: 18 N




m (1.8 kg




m/13 lb ft)
Replacement spark plugs
 Under normal conditions (no problem with the fuel
and/or electrical systems), use replacement spark
plugs with a low heat value (hot-type plug).
 If insulator and electrode scorching is significant,
use replacement spark plugs with a high heat value
(cold-type plug).

6E-70 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Fuel Quality
Fuel quality is not a new issue for the automotive
industry, but its potential for turning on the MIL (“Check
Engine" lamp) with OBD systems is new.
Fuel additives such as “dry gas" and “octane
enhancers" may affect the performance of the fuel. The
Reed Vapor Pressure of the fuel can also create
problems in the fuel system, especially during the spring
and fall months when severe ambient temperature
swings occur. A high Reed Vapor Pressure could sho
w
up as a Fuel Trim DTC due to excessive canister
loading. High vapor pressures generated in the fuel
tank can also affect the Evaporative Emission
diagnostic as well.
Using fuel with the wrong octane rating for your vehicle
may cause driveability problems. Many of the majo
r
fuel companies advertise that using “premium" gasoline
will improve the performance of your vehicle. Mos
t
premium fuels use alcohol to increase the octane rating
of the fuel. Although alcohol-enhanced fuels may raise
the octane rating, the fuel's ability to turn into vapor in
cold temperatures deteriorates. This may affect the
starting ability and cold driveability of the engine.
Low fuel levels can lead to fuel starvation, lean engine
operation, and eventually engine misfire.
Non-OEM Parts
All of the OBD diagnostics have been calibrated to run
with OEM parts.
Aftermarket electronics, such as cellular phones,
stereos, and anti-theft devices, may radiate EMI into the
control system if they are improperly installed. This may
cause a false sensor reading and turn on the MIL
(“Check Engine" lamp).
Environment
Temporary environmental conditions, such as localized
flooding, will have an effect on the vehicle ignition
system. If the ignition system is rain-soaked, it can
temporarily cause engine misfire and turn on the MIL
(“Check Engine" lamp).
Vehicle Marshaling
The transportation of new vehicles from the assembly
plant to the dealership can involve as many as 60 key
cycles within 5Km miles of driving. This type o
f
operation contributes to the fuel fouling of the spark
plugs and will turn on the MIL (“Check Engine" lamp).

Poor Vehicle Maintenance
The sensitivity of OBD diagnostics will cause the MIL
(“Check Engine" lamp) to turn on if the vehicle is no
t
maintained properly. Restricted air filters, fuel filters,
and crankcase deposits due to lack of oil changes o
r
improper oil viscosity can trigger actual vehicle faults
that were not previously monitored prior to OBD. Poo
r
vehicle maintenance can not be classified as a
“non-vehicle fault", but with the sensitivity of OBD
diagnostics, vehicle maintenance schedules must be
more closely followed.
Severe Vibration
The Misfire diagnostic measures small changes in the
rotational speed of the crankshaft. Severe driveline
vibrations in the vehicle, such as caused by an
excessive amount of mud on the wheels, can have the
same effect on crankshaft speed as misfire.
Related System Faults
Many of the OBD system diagnostics will not run if the
ECM detects a fault on a related system or component.
One example would be that if the ECM detected a
Misfire fault, the diagnostics on the catalytic converte
r
would be suspended until Misfire fault was repaired. If
the Misfire fault was severe enough, the catalytic
converter could be damaged due to overheating and
would never set a Catalyst DTC until the Misfire faul
t
was repaired and the Catalyst diagnostic was allowed to
run to completion. If this happens, the customer may
have to make two trips to the dealership in order to
repair the vehicle.
Maintenance Schedule
Refer to the Maintenance Schedule.
Visual/Physical Engine Compartment
Inspection
Perform a careful visual and physical engine
compartment inspection when performing any
diagnostic procedure or diagnosing the cause of an
emission test failure. This can often lead to repairing a
problem without further steps. Use the following
guidelines when performing a visual/physical inspection:

Inspect all vacuum hoses for punches, cuts,
disconnects, and correct routing.

Inspect hoses that are difficult to see behind othe
r
components.

Inspect all wires in the engine compartment fo
r
proper connections, burned or chafed spots, pinched
wires, contact with sharp edges or contact with ho
t
exhaust manifolds or pipes.

6E-194 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Condition For Setting The DTC and Action Taken When The DTC Sets
Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0131 A O2 Sensor Circuit Low
Voltage (Bank 1
Sensor 1) 15
P0151 A O2 Sensor Circuit Low
Voltage (Bank 2
Sensor 1) 1. No DTC relating to ECT sensor, CMP sensor, CKP sensor,
VSS, injector control circuit, ignition control circuit and O2
sensor circuit no activity (bank 1 & 2).
2. Engine speed is between 1000rpm and 4000rpm.
3. Engine coolant temperature is between 70
C and 110
C.
4. Vehicle speed is between 0km/h and 120km/h.
5. Engine load is between 80% and 160%.
6. Throttle position fluctuation is below 0.28V.
7. O2 sensor bank 1 or bank 2 output voltage is more than
400mV for 50 seconds. "Open Loop" fuel control.

CIRCUIT DESCRIPTION
The Engine Control Module (ECM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal high and signal low circuits. The
ECM constantly monitors the HO2S signal during
“closed loop" operation and compensates for a rich o
r
lean condition by decreasing or increasing injector pulse
width as necessary. If HO2S voltage remains
excessively low for an extended period of time, DTC
P0131 or P0151 will be set.
DIAGNOSTIC AIDS
Check for the following conditions:
 Heated oxygen sensor wiring – The sensor pigtail
may be routed incorrectly and contacting the exhaus
t
system.
 Poor ECM to engine block grounds.
 Fuel pressure – The system will go lean if pressure is
too low. The ECM can compensate for some
decrease. However, If fuel pressure is too low, a DTC
P0131 or P0151 may be set. Refer to 6E-116 Fue
l
System Diagnosis.

 Lean injector(s) – Perform “Injector Balance Test."
 Exhaust leaks – An exhaust leak may cause outside
air to be pulled into the exhaust gas stream past the
HO2S, causing the system to appear lean. Check fo
r
exhaust leaks that may cause a false lean condition
to be indicated.
 MAF sensor –The system can go lean if the MAF
sensor signal indicates an engine airflo
w
measurement that is not correct. Disconnect the MAF
sensor to see if the lean condition is corrected. If so,
replace the MAF sensor.
 Fuel contamination –Water, even in small amounts,
can be delivered to the fuel injectors. The water can
cause a lean exhaust to be indicated. Excessive
alcohol in the fuel can also cause this condition.
Refer to 6E-116 Fuel System Diagnosisfor the
procedure to check for fuel contamination.
 If none of the above conditions are present, replace
the affected HO2S.

6E-380 3.5L ENGINE DRIVEABILITY AND EMISSIONS
SPARK PLUGS

Removal Procedure
1. Remove spark plugs.

Inspection Procedure
The spark plug affects entire engine performance and
therefore its inspection is very important.
 Check electrode and insulator for presence o
f
cracks, and replace if any.
 Check electrode for wear, and replace if necessary.
 Check gasket for damage, and replace if necessary.
 Measure insulation resistance with an ohmmeter,
and replace if faulty.
 Adjust spark plug gap to 1.0 mm (0.04 in)

1.1 mm
(0.043 in).
 Check fuel and electrical systems if spark plug is
extremely dirty.
 Use spark plugs having low heat value (hot type
plug) if fuel and electrical systems are normal.
 Use spark plugs having high heat value (cold type
plug) if insulator and electrode are extremely
burned.
Sooty Spark Plugs
Much deposit of carbon or oil on the electrode and
insulator of spark plug reduces the engine performance.
Possible causes:
 Too rich mixture
 Presence of oil in combustion chamber
 Incorrectly adjusted spark plug gap
Burning Electrodes
This fault is characterized by scorched or heavily
oxidized electrode or blistered insulator nose.
Possible causes:
 Too lean mixture
 Improper heat value

Measuring Insulation Resistance
 Measure insulation resistance using a 500 volt
megaohm meter.
 Replace spark plugs if measured value is out o
f
standard.
Insulation resistance: 50 M
  or more




011RS010
Cleaning Spark Plugs
 Clean spark plugs with a spark plug cleaner.
 Raise the ground electrode to an angle of 45 to 60
degrees. If electrode is wet, dry it before cleaning.

After spark plug is thoroughly cleaned, check
insulator for presence of cracks.
 Clean threads and metal body with a wire brush.
 File the electrode tip if electrode is extremely worn.

6F-2 ENGINE EXHAUST (6VE1 3.5L)
General Description



RTW46FLF000101
Legend (3) Three Way Catalytic Converter
(1) Front Exhaust Pipe LH (4) Center Exhaust Pipe
(2) Front Exhaust Pipe RH (5) Exhaust Silencer & Tail Pipe


When inspecting or replacing exhaust system
components, make sure there is adequate clearance
from all points on the underbody to prevent overheating
the floor pan and possible damage to the passenge
r
compartment insulation and trim materials.
Check complete exhaust system and nearby body
areas and rear compartment lid for broken, damaged,
missing or mispositioned parts, open seams, holes,
loose connections or other deterioration which could
permit exhaust fumes to seep into the rea
r
compartment or passenger compartment. Dust or water
in the rear compartment may be an indication of a
problem in one of these areas. Any faulty areas should
be corrected immediately.

Hangers
Various types of hangers are used to support exhaust
system(s). These include conventional rubber straps,
rubber rings, and rubber blocks.
The installation of exhaust system supports is very
important, as improperly installed supports can cause
annoying vibrations which can be difficult to diagnose.
Three Way Catalytic Converter
The three way catalytic converter is an emission control
device added to the exhaust system to reduce
pollutants from the exhaust gas stream.

ENGINE EXHAUST (6VE1 3.5L) 6F-3
CAUTION: The catalytic converter requires the use
of unleaded fuel only.
Periodic maintenance of the exhaust system is no
t
required. If the vehicle is raised for other service, it is
advisable to check the condition of the complete
exhaust system.
A dual bed monolith catalytic converter is used in
combination with three way catalytic converter.
Catalytic Converter Types:
Three way (Reduction/Oxidation) catalyst
The catalyst coating on the three way (reduction)
converter contains platinum and rhodium which lowers
the levels of nitrous oxide (NOx) as well as
hydrocarbons (HC) and carbon monoxide (Co).
Gasket
The gasket must be replaced whenever a new exhaust
pipe, muffler or catalytic converter is installed.