maintenance ISUZU TF SERIES 2004 Owner's Manual

6E-58 3.5L ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR
ELECTRONIC IGNITION SYSTEM IGNITION
COILS & CONTROL
A separate coil-at-plug module is located at each spark
plug.
The coil-at-plug module is attached to the engine with
two screws. It is installed directly to the spark plug by an
electrical contact inside a rubber boot.
A three way connector provides 12 volts primary supply
from the ignition coil fuse, a ground switching trigge
r
line from the ECM, and ground.
The ignition control spark timing is the ECM's method o
f
controlling the spark advance and the ignition dwell.
The ignition control spark advance and the ignition dwell
are calculated by the ECM using the following inputs.

Engine speed

Crankshaft position (CKP) sensor

Camshaft position (CMP) sensor

Engine coolant temperature (ECT) sensor

Throttle position sensor

Park or neutral position switch

Vehicle speed sensor

ECM and ignition system supply voltage

Based on these sensor signal and engine load
information, the ECM sends 5V to each ignition coil
requiring ignition. This signal sets in the powe
r
transistor of the ignition coil to establish a grounding
circuit for the primary coil, applying battery voltage to
the primary coil.
At the ignition timing, the ECM stops sending the 5V
signal voltage. Under this condition the power transistor
of the ignition coil is set off to cut the battery voltage to
the primary coil, thereby causing a magnetic field
generated in the primary coil to collapse.
On this moment a line of magnetic force flows to the
secondary coil, and when this magnetic line crosses the
coil, high voltage induced by the secondary ignition
circuit to flow through the spark plug to the ground.

Ignition Control ECM Output
The ECM provides a zero volt (actually about 100 mV to
200 mV) or a 5-volt output signal to the ignition control
(IC) module. Each spark plug has its own primary and
secondary coil module ("coil-at-plug") located at the
spark plug itself. When the ignition coil receives the
5-volt signal from the ECM, it provides a ground path fo
r
the B+ supply to the primary side of the coil-at -plug
module. This energizes the primary coil and creates a
magnetic field in the coil-at-plug module. When the
ECM shuts off the 5-volt signal to the ignition control
module, the ground path for the primary coil is broken.
The magnetic field collapses and induces a high voltage
secondary impulse which fires the spark plug and
ignites the air/fuel mixture.
The circuit between the ECM and the ignition coil is
monitored for open circuits, shorts to voltage, and
shorts to ground. If the ECM detects one of these
events, it will set one of the following DTCs:

P0351: Ignition coil Fault on Cylinder #1

P0352: Ignition coil Fault on Cylinder #2

P0353: Ignition coil Fault on Cylinder #3

P0354: Ignition coil Fault on Cylinder #4

P0355: Ignition coil Fault on Cylinder #5

P0356: Ignition coil Fault on Cylinder #6

Spark Plug
Although worn or dirty spark plugs may give satisfactory
operation at idling speed, they frequency fail at highe
r
engine speeds. Faulty spark plugs may cause poor fuel
economy, power loss, loss of speed, hard starting and
generally poor engine performance. Follow the
scheduled maintenance service recommendations to
ensure satisfactory spark plug performance. Refer to
Maintenance and Lubrication.
Normal spark plug operation will result in brown to
grayish-tan deposits appearing on the insulator portion
of the spark plug. A small amount of red-brown, yellow,
and white powdery material may also be present on the
insulator tip around the center electrode. These
deposits are normal combustion by-products of fuels
and lubricating oils with additives. Some electrode wea
r
will also occur. Engines which are not running properly
are often referred to as “misfiring." This means the
ignition spark is not igniting the air/fuel mixture at the
proper time.
Spark plugs may also misfire due to fouling, excessive
gap, or a cracked or broken insulator. If misfiring
occurs before the recommended replacement interval,
locate and correct the cause.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-59
Carbon fouling of the spark plug is indicated by dry,
black carbon (soot) deposits on the portion of the spark
plug in the cylinder. Excessive idling and slow speeds
under light engine loads can keep the spark plug
temperatures so low that these deposits are not burned
off. Very rich fuel mixtures or poor ignition system
output may also be the cause. Refer to DTC P0172.
Oil fouling of the spark plug is indicated by wet oily
deposits on the portion of the spark plug in the cylinder,
usually with little electrode wear. This may be caused by
oil during break-in of new or newly overhauled engines.
Deposit fouling of the spark plug occurs when the
normal red-brown, yellow or white deposits o
f
combustion by products become sufficient to cause
misfiring. In some cases, these deposits may melt and
form a shiny glaze on the insulator around the cente
r
electrode. If the fouling is found in only one or two
cylinders, valve stem clearances or intake valve seals
may be allowing excess lubricating oil to enter the
cylinder, particularly if the deposits are heavier on the
side of the spark plug facing the intake valve.



TS23995
Excessive gap means that the air space between the
center and the side electrodes at the bottom of the
spark plug is too wide for consistent firing. This may be
due to excessive wear of the electrode during use.
A
check of the gap size and comparison to the gap
specified for the vehicle in Maintenance and Lubrication
will tell if the gap is too wide. A spark plug gap that is
too small may cause an unstable idle condition.
Excessive gap wear can be an indication of continuous
operation at high speeds or with engine loads, causing
the spark to run too hot. Another possible cause is an
excessively lean fuel mixture.



TS23992
Low or high spark plug installation torque or improper
seating can result in the spark plug running too hot and
can cause excessive center electrode wear. The plug
and the cylinder head seats must be in good contact fo
r
proper heat transfer and spark plug cooling. Dirty or
damaged threads in the head or on the spark plug can
keep it from seating even though the proper torque is
applied. Once spark plugs are properly seated, tighten
them to the torque shown in the Specifications Table.
Low torque may result in poor contact of the seats due
to a loose spark plug. Over tightening may cause the
spark plug shell to be stretched and will result in poo
r
contact between the seats. In extreme cases, exhaus
t
blow-by and damage beyond simple gap wear may
occur.
Cracked or broken insulators may be the result o
f
improper installation, damage during spark plug heat
shock to the insulator material. Upper insulators can be
broken when a poorly fitting tool is used during
installation or removal, when the spark plug is hit from
the outside, or is dropped on a hard surface. Cracks in
the upper insulator may be inside the shell and no
t
visible. Also, the breakage may not cause problems
until oil or moisture penetrates the crack later.

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.

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.

ENGINE DIAGNOSIS (C24SE) 6-13
Fuel Consumption Excessive
Condition Possible cause Correction
Trouble in fuel system Mixture too rich or too lean due to
trouble in fuel injection system Refer to "Abnormal Combustion"
Fuel cut function does not act Refer to "Abnormal Combustion"
Trouble in ignition system Misfiring or abnormal combustion
due to trouble in ignition system Refer to Hard Start or Abnormal
Combustion Troubleshooting
Guide
Others Engine idle speed too high Reset Idle Air Control Valve
Returning of accelerator control
sluggish Correct
Fuel system leakage Correct or replace
Clutch slipping Correct
Brake drag Correct
Selection of transmission gear
incorrect Caution operator of incorrect gear
selection
Oil Problems
Condition Possible cause Correction
Oil pressure too low Wrong oil in use Replace with correct engine oil
Relief valve sticking Replace
Oil pump not operating properly Correct or replace
Oil pump strainer clogged Clean or replace strainer
Oil pump worn Replace
Oil pressure gauge defective Correct or replace
Crankshaft bearing or connecting
rod bearing worn Replace
Oil contamination Wrong oil in use Replace with new engine oil
Oil filter clogged Replace oil filter
Cylinder head gasket damage Replace gasket
Burned gases leaking Replace piston and piston rings or
rebore cylinders
Oil not reaching valve system Oil passage in cylinder head or
cylinder body clogged Clean or correct

Engine Oil Pressure Check
1. Check for dirt, gasoline or water in the engine
oil.
a. Check the viscosity of the oil.
b. Change the oil if the viscosity is outside the
specified standard.
c. Refer to the "Maintenance and Lubrication"
section of this manual.
2. Check the engine oil level.
The level should fall somewhere between the
"ADD" and the "FULL" marks on the oil level
dipstick.
If the oil level does not reach the "ADD" mark on
the oil level dipstick, engine oil must be added. 3. Remove the oil pressure unit.
4. Install an oil pressure gauge.
5. Start the engine and allow the engine to reach
normal operating temperature (About 80
C).
6. Measure the oil pressure.
Oil pressure should be:
150 kPa(21.8 psi) at idle speed.
7. Stop the engine.
8. Remove the oil pressure gauge
9. Install the oil pressure unit.
10. Start the engine and check for leaks.

6C-6 ENGINE FUEL (C24SE)
Fuel Filter
Inspection
1. Replace the fuel filter if the fuel leaks from fuel filter
body or if the fuel filter body itself is damaged.
2. Replace the filter if it is clogged with dirt o
r
sediment.
Installation
1. Install the filter to holder from side member side.
NOTE: Attend direction of fuel filter. (1) to engine side
(2) to fuel tank side.
NOTE: Verify to hang holder hook to fuel filter.


NOTE: Verify to hang holder hook to fuel filter.




RTW36CSH000301
2. Connect the quick connector from the fuel tube to
the fuel filter.
NOTE: Pull of the left checker into the fuel pipe.
NOTE: Refer to “Fuel Tube/Quick Connector Fittings” in
this section when performing any repairs.
3. Tighten fuel filler cap until at least one click are
heard.
4. Connect the battery ground cable.
Inspection
After installation, start engine and check for fuel
leakage.
In–Tank Fuel Filter
The filter is located on the lower end of fuel pickup tube
in the fuel tank. It prevents dirt from entering the fuel
pipe and also stops water unless the filter is completely
submerged in the water. It is a selfcleaning type, no
t
requiring scheduled maintenance. Excess water and
sediment in the tank restricts fuel supply to the engine,
resulting in engine stoppage. In such a case, the tank
must be cleaned thoroughly.

STARTING AND CHARGING SYSTEM 6D3-7

Charging System
General Description
The charging system is an IC integral regulator charging
system and its main components are connected as shown in
illustration.
The regulator is a solid state type and it is mounted along with
the brush holder assembly inside the generator installed on the
rear end cover.
The generator does not require particular maintenance such as
voltage adjustment. The rectifier connected to the stator coil
has eight diodes to transform AC voltage into DC voltage.
This DC voltage is connected to the output terminal of
generator.

Legend
1 Startor assembly
2 Housing
3 Slipring
4 Screws (2)
5 Regulator
6.Bolt (4)7 Rectifier assem bly
8 Retaining assem bly
9 B+ terminal nut and washer
10 Pulley
11 Rotor assembly
12 Ball bearing
2
11
12
28 54
31
11 7 6 10
9

STARTING AND CHARGING SYSTEM 6D3-19
Inspection
Generator
Before any in field testing can be undertaken it is important
that the battery's conditions is established and the terminals
are clean and tight.

Check the condition of the generator drive belt and ensure that
it is adjusted in accordance with the engine manufacturer's
recommnedations.

Battery conditions:
Note: This assessment may be difficult with maintenance free
assemblies.

Test the specific gravity of the individual cells the readings
should be within 10 points of each other, it is recommended
that the average SG should be 1.260 or higher.
A load test should be carried out to determine the ability of the
battery to supply and accept current. This is a good indicator
as to the general condition of the battery.
A load equal to the normal starting current should be placed
across the battery, the duration of this load test should not
exceed 10 seconds, during this time the terminal voltage
across the battery should not drop below 9.6 volts. Observe
each cell for signs of excessive gas liberation, usuall an
indication of cell failure.
If the battery test is clear proceed with the Generator tests as
follows.

Care should be taken when making the following connections.
It is recommended that the battery negative terminal be
disconnected before the test meters are connected, and
reconnecting the negative terminal when the meters are
inserted into the circuit under test. The warning lamp in the D+
circuit should not exceed 2 watts.

Regulating voltage test on the vehicle.
Connect a voltmeter to the generator, the positive lead to the
B+ terminal and the nagative lead to the generator casing.
Select the voltage range to suit the system, i.e. 20v for 12 volt
sysytems or 40v for 24 volt systems. Connect an ammeter in
series with the main output cable from the B+ terminal on the
generator, the range selected must be capable of reading the
maximum output from the generator.

Note the voltmeter reading before starting the engine. This
reading should increase when the engine is running indicating
generator output, start the engine and increase the engine
speed until the generator is running at 4000 rpm, switch on
vehicle loads of 5-10 A is indcated on the ammeter, the
voltmeter shoud read 14.0-14.2 v for a 12 volt system, for a 24
volt system the readings should be 5-10 A and 27.7-28.5 volts.

6E–54 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR ELECTRIC
IGNITION SYSTEM
The engine use two ignition coils, one per two cylinders.
A two wire connector provides a battery voltage primary
supply through the ignition fuse.
The ignition control spark timing is the ECM’s method of
controlling the spark advance and the ignition dwell.
The ignition control spark advance and the ignition dwell
are calculated by the ECM using the following inputs.
Engine speed
Crankshaft position (CKP) sensor
Engine coolant temperature (ECT) sensor
Throttle position sensor
Vehicle speed sensor
ECM and ignition system supply voltage
Ignition coil works to generate only the secondary
voltage be receiving the primary voltage from ECM.
The primary voltage is generated at the coil driver
located in the ECM. The coil driver generate the primary
voltage based on the crankshaft position signal. In
accordance with the crankshaft position signal, ignition
coil driver determines the adequate ignition timing and
also cylinder number to ignite.
Ignition timing is determined the coolant temperature,
intake air temperature, engine speed, engine load,
knock sensor signal, etc.
Spark Plug
Although worn or dirty spark plugs may give satisfactory
operation at idling speed, they frequently fail at higher
engine speeds. Faulty spark plugs may cause poor fuel
economy, power loss, loss of speed, hard starting and
generally poor engine performance. Follow the
scheduled maintenance service recommendations to
ensure satisfactory spark plug performance. Refer to
Maintenance and Lubrication.
Normal spark plug operation will result in brown to
grayish-tan deposits appearing on the insulator portion
of the spark plug. A small amount of red-brown, yellow,
and white powdery material may also be present on the
insulator tip around the center electrode. These
deposits are normal combustion by-products of fuels
and lubricating oils with additives. Some electrode wear
will also occur. Engines which are not running properly
are often referred to as “misfiring.” This means the
ignition spark is not igniting the air/fuel mix ture at the
proper time. While other ignition and fuel system causes
must also be considered, possible causes include
ignition system conditions which allow the spark voltage
to reach ground in some other manner than by jumping
across the air gap at the tip of the spark plug, leaving
the air/fuel mix ture unburned. Misfiring may also occur
when the tip of the spark plug becomes overheated and
ignites the mixture before the spark jumps. This is
referred to as “pre-ignition.”
Spark plugs may also misfire due to fouling, ex cessive
gap, or a cracked or broken insulator. If misfiring occursbefore the recommended replacement interval, locate
and correct the cause.
Carbon fouling of the spark plug is indicated by dry,
black carbon (soot) deposits on the portion of the spark
plug in the cylinder. Ex cessive idling and slow speeds
under light engine loads can keep the spark plug
temperatures so low that these deposits are not burned
off. Very rich fuel mix tures or poor ignition system output
may also be the cause. Refer to DTC P1167.
Oil fouling of the spark plug is indicated by wet oily
deposits on the portion of the spark plug in the cylinder,
usually with little electrode wear. This may be caused by
oil during break-in of new or newly overhauled engines.
Deposit fouling of the spark plug occurs when the
normal red-brown, yellow or white deposits of
combustion by-products become sufficient to cause
misfiring. In some cases, these deposits may melt and
form a shiny glaze on the insulator around the center
electrode. If the fouling is found in only one or two
cylinders, valve stem clearances or intake valve seals
may be allowing ex cess lubricating oil to enter the
cylinder, particularly if the deposits are heavier on the
side of the spark plug facing the intake valve.
Ex cessive gap means that the air space between the
center and the side electrodes at the bottom of the
spark plug is too wide for consistent firing. This may be
due to improper gap adjustment or to ex cessive wear of
the electrode during use. A check of the gap size and
comparison to the gap specified for the vehicle in
Maintenance and Lubrication will tell if the gap is too
wide. A spark plug gap that is too small may cause an
unstable idle condition. Ex cessive gap wear can be an
indication of continuous operation at high speeds or
with engine loads, causing the spark to run too hot.
Another possible cause is an ex cessively lean fuel
mixture.

ENGINE DRIVEABILITY AND EMISSIONS 6E–67
GENERAL SERVICE INFORMATION
Aftermarket Electrical and Vacuum
Equipment
Aftermarket (add-on) electrical and vacuum equipment
is defined as any equipment which connects to the
vehicle's electrical or vacuum systems that is installed
on a vehicle after it leaves the factory. No allowances
have been made in the vehicle design for this type of
equipment.
NOTE: No add-on vacuum equipment should be added
to this vehicle.
NOTE: Add-on electrical equipment must only be
connected to the vehicle's electrical system at the
battery (power and ground).
Add-on electrical equipment, even when installed to
these guidelines, may still cause the electric system to
malfunction. This may also include equipment not
connected to the vehicle electrical system such as
portable telephones and radios. Therefore, the first step
in diagnosing any electric problem is to eliminate all
aftermarket electrical equipment from the vehicle. After
this is done, if the problem still ex ists, it may be
diagnosed in the normal manner.
Electrostatic Discharge Damage
Electronic components used in the ECM are often
designed to carry very low voltage. Electronic
components are susceptible to damage caused by
electrostatic discharge. Less than 100 volts of static
electricity can cause damage to some electronic
components. By comparison, it takes as much as 4000
volts for a person to feel even the zap of a static
discharge.
There are several ways for a person to become
statically charged. The most common methods of
charging are by friction and induction.
An ex ample of charging by friction is a person sliding
across a vehicle seat.
Charge by induction occurs when a person with well-
insulated shoes stands near a highly charged object
and momentarily touches ground. Charges of the
same polarity are drained off leaving the person
highly charged with the opposite polarity. Static
charges can cause damage, therefore it is important
to use care when handling and testing electronic
components.Non-OEM Parts
All of the OBD diagnostics have been calibrated to run
with OEM parts. Accordingly, if commercially sold
sensor or switch is installed, it makes a wrong diagnosis
and turns on the check engine lamp.
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 check
engine lamp.
Poor Vehicle Maintenance
The sensitivity of OBD diagnostics will cause the check
engine lamp to turn on if the vehicle is not maintained
properly. Restricted oil filters, fuel filters, and crankcase
deposits due to lack of oil changes or improper oil
viscosity can trigger actual vehicle faults that were not
previously monitored prior to OBD. Poor 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
follow ed.
Related System Faults
Many of the OBD system diagnostics will not run if the
ECM detects a fault on a related system or component.
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 other
components.
Inspect all wires in the engine compartment for
proper connections, burned or chafed spots, pinched
wires, contact with sharp edges or contact with hot
exhaust manifolds or pipes.
Basic Knowledge of Tools Required
NOTE: Lack of basic knowledge of this powertrain
when performing diagnostic procedures could result in
an incorrect diagnosis or damage to powertrain
components. Do not attempt to diagnose a powertrain
problem without this basic knowledge.
A basic understanding of hand tools is necessary to
effectively use this section of the Service Manual.