ignition ISUZU TF SERIES 2004 Workshop Manual

6E–8 ENGINE DRIVEABILITY AND EMISSIONS
1234
(1)
(2)Injector #1 Cylinder
Injector #2 Cylinder (3)
(4)Injector #3 Cylinder
Injector #4 Cylinder (Under the ECM)
(1) Ignition Coil Module Assembly
(1) Heated Ox ygen Sensor (HO2S)

6E–28 ENGINE DRIVEABILITY AND EMISSIONS
CONNECTOR LIST
No. Connector face No. Connector face
B-24
Green Meter-BC-122
CO Adjuster
B-58
Black Check connectorE-6
Fuel injector
B-62
White Ignition switch (IGSUB : G1)E-7
Fuel injector
B-63
White Ignition switch (IGSUB : G2)E-8
Fuel injector
B-68
ImmobilizerE-9
Fuel injector
C-2
Silver Engine room-RH groundE-18
Ignition coil
C-56
ECME-60
ECM
C-107
White J/B E2E-72
Engine earth-A
C-108
White J/B E1E-74
Engine earth-B
C-121
IAT sensorE-77
O
2 sensor

6E–46 ENGINE DRIVEABILITY AND EMISSIONS
Reference Wave Form
Crankshaft Position (CKP) Sensor Reference Wave Form









0V








Measurem ent Term inal: J1-21(+) J1-6(-)
Measurem ent Scale: 10V/div 5m s/div
Measurem ent Condition: Approximately 2000rpm
Vehicle Speed Sensor (VSS) Reference Wave Form








CH1
0V


CH2
0V






Measurement Term inal: CH1: ECM J2-23(+) / CH2: VSS 3(+) GND(-)
Measurem ent Scale: CH1: 10V/div / CH2: 10V/div 50m s/div
Measurem ent Condition: A pproximately 20km /h
Note: The vehicle is without im mobilizer system,
CH1 signal is same as CH2.

Injector Control Signal Reference Wave Form









0V








Measurem ent Terminal: J1-9(+) (No.1 Cylinder) GND(-)
Measurem ent Scale: 20V/div 5m s/div
Measurement Condition: Approxim ately 2000rpm
Crankshaft Position (CKP) Sensor & Tacho Output Signal
R e fe rence Wa ve Fo rm
CH1
0V

CH2
0V

Measurement Terminal: CH1: J1-21(+) / CH2: J2-25(+) GND(-)
Measurement Scale: CH1: 2V/div / CH2: 10V/div 5ms/div
Measurement Condition: Approximately 2000rpm
Heated Oxygen Sensor (HO2S) Reference Wave Form









0V








Measurement Terminal: J2-21(+) GND(-)
Measurement Scale: 500m V/div 500m s/div
Measurem ent Condition: Approxim ately 2000rpm in Closed Loop
Ignition Coil Control Signal Reference Wave Form








CH1
0V


CH2
0V




Measurem ent Term inal: CH1: J1-19(+) / CH2: J1-18(+) GND(-)
Measurement Scale: CH1: 20V/div / CH2: 20V/div 10m s
Measurem ent Condition: Approxim ately 2000rpm

6E–48 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR ECM AND
SENSORS
Engine Control Module (ECM)
The engine control module (ECM) is located on the
intake manifold. The ECM controls the following.
Fuel metering system
Ignition timing
On-board diagnostics for electrical functions.
The ECM constantly observes the information from vari-
ous sensors. The ECM controls the systems that affect
vehicle performance. And it performs the diagnostic
function of the system.
The function can recognize operational problems, and
warn to the driver through the check engine lamp, and
store diagnostic trouble code (DTC). DTCs identify the
problem areas to aid the technician in marking repairs.
The input / output devices in the ECM include analog to
digital converts, signal buffers, counters and drivers.
The ECM controls most components with electronic
switches which complete a ground circuit when turned
on.
Inputs (Operating condition read):
Battery voltage
Electrical ignition
Ex haust oxygen content
Intake manifold pressure
Intake air temperature
Engine coolant temperature
Crankshaft positionKnock signal
Throttle position
Vehicle speed
Power steering pressure
Air conditioning request on or off
Outputs (Systems controlled):
Ignition control
Fuel control
Idle air control
Fuel pump
EVAP canister purge
Air conditioning
Diagnostics functions
Manifold Absolute Pressure (MAP) Sensor
The MAP sensor is a strain gage. A pressure strains the
resistance on the silicon base. At that time the
resistance value changes. And it changes voltage. In
other words it measures a pressure value. It is installed
to the intake manifold. Output voltage of the MAP
sensor is low as pressure is low. (1) J1 Port
(2) J2 Port
12
C h arac teris tic of MA P S ens or -R ef erenc e-
0 0.51 1.52 2.53 3.54 4.55
15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
Mani fold A bs olute P res s ure (K P a) (T ec h2 Reading)
Output Voltage (V)

ENGINE DRIVEABILITY AND EMISSIONS 6E–49
Throttle Position Sensor (TPS)
The TPS is a potentiometer connected to throttle shaft
on the throttle body.
The engine control module (ECM) monitors the voltage
on the signal line and calculates throttle position. As the
throttle valve angle is changed when accelerator pedal
moved. The TPS signal also changed at a moved
throttle valve. As the throttle valve opens, the output
increases so that the output voltage should be high.
The throttle body has a throttle plate to control the
amount of the air delivered to the engine.
Engine coolant is directed through a coolant cavity in
the throttle body to warm the throttle valve and to
prevent icing.
Idle Air Control (IAC) Valve
The idle air control valve (IAC) valve is two directional
and gives 2-way control. With power supply to the coils
controlled steps by the engine control module (ECM),
the IAC valve's pintle is moved to adjust idle speed,
raising it for fast idle when cold or there is ex tra load
from the air conditioning or power steering.
By moving the pintle in (to decrease air flow) or out (to
increase air flow), a controlled amount of the air can
move around the throttle plate. If the engine speed is
too low, the engine control module (ECM) will retract the
IAC pintle, resulting in more air moving past the throttle
plate to increase the engine speed.
If the engine speed is too high, the engine control
module (ECM) will ex tend the IAC pintle, allowing less
air to move past the throttle plate, decreasing the
engine speed.
The IAC pintle valve moves in small step called counts.
During idle, the proper position of the IAC pintle is
calculated by the engine control module (ECM) based
on battery voltage, coolant temperature, engine load,
and engine speed.
If the engine speed drops below a specified value, and
the throttle plate is closed, the engine control module
(ECM) senses a near-stall condition. The engine control
module (ECM) will then calculate a new IAC pintle valve
position to prevent stalls.
If the IAC valve is disconnected and reconnected with
the engine running, the idle speed will be wrong. In this
case, the IAC must be reset. The IAC resets when the
key is cycled “On” then “Off”. When servicing the IAC, it
should only be disconnected or connected with the
ignition “Off”.
The position of the IAC pintle valve affects engine start-
up and the idle characteristic of the vehicle.
If the IAC pintle is fully open, too much air will be
allowed into the manifold. This results in high idle
speed, along with possible hard starting and lean air/
fuel ratio. (1) Throttle Position Sensor
(2) Idle Air Control (IAC) Valve
1
2
C haract erist ic of TPS -R ef erenc e-
0 0. 51 1. 52 2. 53 3. 54 4. 55
0 102030405060708090100
Th rot t le An gle ( % ) ( Tec h 2 R ea di n g)
Output Voltage (V)
StepCoilAB CDCoil A High
(EC M J1-28)On On
Coil A Low
(EC M J1-30)On On
Coil B High
(EC M J1-13)On On
Coil B Low
(EC M J1-29)On On

(IAC Valve Close Direction)
(IAC Valve Open Direction)

6E–50 ENGINE DRIVEABILITY AND EMISSIONS
Crankshaft Position (CKP) Sensor
The crankshaft position (CKP) sensor, which sends a
signal necessary for deciding on injection timing to the
ECM, is mounted on the left-hand side of the cylinder
block just back of the A/C compressor.
The crankshaft has a 58 teeth press-fit timing disc, from
which the CKP sensor reads the position of the
crankshaft at all the times. It converts this to an
electrical signal, which it sends to the ECM.
Using the 58 X signals per rotation and the timing-mark
signal sent by the CKP sensor, the ECM is able to
accurately calculate engine speed and crank position.
The ECM converts the 58 X signals into square signals.
This converted signal is sent from the ECM terminal J2-
25 to the tachometer.
Knock Sensor (KS)
The knock sensor (KS) contains an element that
converts detection of knock into an electrical signal, and
is mounted on cylinder block wall.
When the ECM receives a signal that indicates knock,
the ECM orders ignition timing to be adjusted to
compensate.
Engine Coolant Temperature (ECT) Sensor
The ECT sensor is a thermistor. A temperature changes
the resistance value. And it changes voltage. In other
words it measures a temperature value. It is installed on
the coolant stream. Low coolant temperature produces
a high resistance.
The ECM supplies 5 volts signal to the ECT sensor
through resisters in the ECM and measures the voltage.
The signal voltage will be high when the engine
temperature is cold, and it will be low when the engine
temperature is hot.

Ch aract erist ic of ECT Sens or -Ref erenc e-
10 100 1000 10000 100000
-20-100 10203040 5060708090100110120
Cool ant Temp. ( deg . C ) ( Tech2 R eadi ng )
Resistance (ohm) (Solid Line)

6E–52 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR FUEL
METERING
The fuel metering system starts with the fuel in the fuel
tank. An electric fuel pump, located in the fuel tank,
pumps fuel to the fuel rail through an in-line fuel filter.
The pump is designed to provide fuel at a pressure
above the pressure needed by the injectors.
A fuel pressure regulator in the fuel rail keeps fuel
available to the fuel injectors at a constant pressure.
A return line delivers unused fuel back to the fuel tank.
The basic function of the air/fuel metering system is to
control the air/fuel delivery to the engine. Fuel is
delivered to the engine by individual fuel injectors
mounted in the intake manifold.
The main control sensor is the heated ox ygen sensor
located in the ex haust system. The heated ox ygen
sensor reports to the ECM how much oxygen is in the
ex haust gas. The ECM changes the air/fuel ratio to the
engine by controlling the amount of time that fuel
injector is “On”.
The best mix ture to minimize exhaust emissions is 14.7
parts of air to 1 part of gasoline by weight, which allows
the catalytic converter to operate most efficiently.
Because of the constant measuring and adjusting of the
air/fuel ratio, the fuel injection system is called a “closed
loop” system.
The ECM monitors signals from several sensors in
order to determine the fuel needs of the engine. Fuel is
delivered under one of several conditions called “mode”.
All modes are controlled by the ECM.
Battery Voltage Correction Mode
When battery voltage is low, the ECM will compensate
for the weak spark by increasing the following:
The amount of fuel delivered.
The idle RPM.
Clear Flood Mode
Clear a flooded engine by pushing the accelerator pedal
down all the way. The ECM then de-energizes the fuel
injectors. The ECM holds the fuel injectors de-energized
as long as the throttle remains above 75% and the
engine speed is below 800 RPM. If the throttle position
becomes less than 75%, the ECM again begins to pulse
the injectors ON and OFF, allowing fuel into the
cylinders.
Deceleration Fuel Cutoff (DFCO) Mode
The ECM reduces the amount of fuel injected when it
detects a decrease in the throttle position and the air
flow. When deceleration is very fast, the ECM may cut
off fuel completely. Until enable conditions meet the
engine revolution less 1000 rpm or manifold absolute
pressure less than 10 kPa.
Engine Speed/ Vehicle Speed/ Fuel Disable
Mode
The ECM monitors engine speed. It turns off the fuel
injectors when the engine speed increases above 6000
RPM. The fuel injectors are turned back on when
engine speed decreases below 3500 RPM.
Acceleration Mode
The ECM provides ex tra fuel when it detects a rapid
increase in the throttle position and the air flow.
Fuel Cutoff Mode
No fuel is delivered by the fuel injectors when the
ignition is OFF. This prevents engine run-on. In addition,
the ECM suspends fuel delivery if no reference pulses
are detected (engine not running) to prevent engine
flooding.
Starting Mode
When the ignition is first turned ON, the ECM energizes
the fuel pump relay for two seconds to allow the fuel
pump to build up pressure. The ECM then checks the
engine coolant temperature (ECT) sensor and the
throttle position sensor to determine the proper air/fuel
ratio for starting.
The ECM controls the amount of fuel delivered in the
starting mode by adjusting how long the fuel injectors
are energized by pulsing the injectors for very short
times.
Run Mode
The run mode has the following two conditions:
Open loop
Closed loop
When the engine is first started, the system is in “open
loop” operation. In “Open Loop,” the ECM ignores the
signal from the heated oxygen sensor (HO2S). It
calculates the air/fuel ratio based on inputs from the TP,
ECT, and MAP sensors.
The system remains in “Open Loop” until the following
conditions are met:
The HO2S has a varying voltage output showing that
it is hot enough to operate properly (this depends on
temperature).
The ECT has reached a specified temperature.
A specific amount of time has elapsed since starting
the engine.
Engine speed has been greater than a specified RPM
since start-up.
The specific values for the above conditions vary with
different engines and are stored in the programmable
read only memory (PROM). When these conditions are
met, the system enters “closed loop” operation. In
“closed loop,” the ECM calculates the air/fuel ratio
(injector on-time) based on the signal from the HO2S.
This allows the air/fuel ratio to stay very close to 14.7:1.

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–57
GENERAL DESCRIPTION FOR
EVAPORATIVE EMISSION SYSTEM
EVAP Emission Control System Purpose
The basic evaporative emission control system used on
the charcoal canister storage method. The method
transfers fuel vapor from the fuel tank to an activated
carbon (charcoal) storage devise to hold the vapors
when the vehicle is not operating.
The canister is located on the rear ax le housing by the
frame cross-member.
When the engine is running, the fuel vapor is purged
from the carbon element by intake air flow and
consumed in the normal combustion process.
EVAP Emission Control System Operation
The EVAP canister purge is controlled by a solenoid
valve that allows the manifold vacuum to purge the
canister. The engine control module (ECM) supplies a
ground to energize the solenoid valve (purge on). The
EVAP purge solenoid control is pulse-width modulated
(PWM) (turned on and off several times a second). The
duty cycle (pulse width) is determined by engine
operating conditions including load, throttle position,
coolant temperature and ambient temperature. The duty
cycle is calculated by the ECM. the output is
commanded when the appropriate conditions have
been met. These conditions are:
The engine is fully warmed up.
The engine has been running for a specified time.
The IAT reading is above 10°C (50°F).
Purge/Vacuum Hoses. Made of rubber compounds,
these hoses route the gasoline fumes from their
sources to the canister and from the canister to the
intake air flow.
EVAP Canister. Mounted on a bracket ahead of the
fuel tank, the canister stores fuel vapors until the
ECM determined that engine conditions are right for
them to be removed and burned.
Poor idle, stalling and Poor driveability can be caused
by:
A malfunctioning purge solenoid.
A damaged canister.
Hoses that are split, cracked, or not connected
properly.
System Fault Detection
The EVAP leak detection strategy is based on applying
vacuum to the EVAP system and monitoring vacuum
decay. At an appropriate time, the EVAP purge solenoid
is turned “ON,” allowing the engine vacuum to draw a
small vacuum on the entire evaporative emission
system.
After the desired vacuum level has been achieved, the
EVAP purge solenoid is turned “OFF,” sealing the
system. A leak is detected by monitoring for a decrease
in vacuum level over a given time period, all other
variables remaining constant.
If the desired vacuum level cannot be achieved in the
test described above, a large leak or a faulty EVAP
purge control solenoid valve is indicated.
Leaks can be caused by the following conditions:
Missing or faulty fuel cap
Disconnected, damaged, pinched, or blocked EVAP
purge line
Disconnected, damaged, pinched, or blocked fuel
tank vapor line
Disconnected or faulty EVAP purge control solenoid
valve
Open ignition feed circuit to the purge solenoid (1) Purge Solenoid Valve
(2) From Canistor to Purge Solenoid
(3) From Purge Solenoid to Intake
(1) Canistor
(2) Air Separator
132
12

6E–68 ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD)
On-Board Diagnostic Tests
A diagnostic test is a series of steps, the result of which
is a pass or fail reported to the diagnostic ex ecutive.
When a diagnostic test reports a pass result, the
diagnostic ex ecutive records the following data:
The diagnostic test has been completed since the
last ignition cycle.
The diagnostic test has passed during the current
ignition cycle.
The fault identified by the diagnostic test is not
currently active.
When a diagnostic test reports a fail result, the
diagnostic ex ecutive records the following data:
The diagnostic test has been completed since the
last ignition cycle.
The fault identified by the diagnostic test is currently
active.
The fault has been active during this ignition cycle.
The operating conditions at the time of the failure.
The Diagnostic Executive
The Diagnostic Executive is a unique segment of
software which is designed to coordinate and prioritize
the diagnostic procedures as well as define the protocol
for recording and displaying their results. The main
responsibilities of the Diagnostic Ex ecutive are listed as
follows:
Commanding the check engine lamp on and off
DTC logging and clearing
Current status information on each diagnostic
Diagnostic Information
The diagnostic charts and functional checks are
designed to locate a faulty circuit or component through
a process of logical decisions. The charts are prepared
with the requirement that the vehicle functioned
correctly at the time of assembly and that there are not
multiple faults present.
There is a continuous self-diagnosis on certain control
functions. This diagnostic capability is complemented
by the diagnostic procedures contained in this manual.
The language of communicating the source of the
malfunction is a system of diagnostic trouble codes.
When a malfunction is detected by the control module, a
diagnostic trouble code is set and the check engine
lamp is illumi nated.
Check Engine Lamp
The check engine lamp looks the same as the check
engine lamp you are already familiar with, the “Check
Engine” lamp.
Basically, the check engine lamp is turned on when the
ECM detects a DTC that will impact the vehicle
emissions.
When the check engine lamp remains “ON” while the
engine is running, or when a malfunction issuspected due to a driveability or emissions problem,
a Powertrain On-Board Diagnostic (OBD) System
Check must be performed. The procedures for these
checks are given in On-Board Diagnostic (OBD)
System Check. These checks will ex pose faults
which may not be detected if other diagnostics are
performed first.
Data Link Connector (DLC)
The provision for communication with the contorl
module is the Data Link Connector (DLC). It is located
behind the lower front instrument panel. The DLC is
used to connect to a Tech 2. Some common uses of the
Tech 2 are listed below:
Identifying stored Diagnostic Trouble Codes (DTCs).
Clearing DTCs.
Reading serial data.
Ver ify in g Veh icle Repair
Verification of vehicle repair will be more
comprehensive for vehicles with OBD system
diagnostic. Following a repair, the technician should
perform the following steps:
1. Review and record the Fail Records for the DTC
which has been diagnosed.
2. Clear DTC(s).
3. Operate the vehicle within conditions noted in the
Fail Records.
4. Monitor the DTC status information for the specific
DTC which has been diagnosed until the diagnostic
test associated with that DTC runs.
Following these steps is very important in verifying
repairs on OBD systems. Failure to follow these steps
could result in unnecessary repairs.