2004 ISUZU TF SERIES injector

6E-56 3.5L 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 oxygen senso
r
located in the exhaust system. The heated oxygen
sensor reports to the ECM how much oxygen is in the
exhaust gas. The ECM changes the air/fuel ratio to the
engine by controlling the amount of time that fuel
injector is "On".
The best mixture 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.

Acceleration Mode
The ECM provides extra fuel when it detects a rapid
increase in the throttle position and the air flow.

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.

Ignition dwell time.

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 80%
and the engine speed is below 800 RPM. If the throttle
position becomes less than 80%, the ECM again begins
to pulse the injectors "ON" and "OFF," allowing fuel into
the cylinders.

Deceleration Mode
The ECM reduces the amount of fuel injected when i
t
detects a decrease in the throttle position and the air
flow. When deceleration is very fast, the ECM may cu
t
off fuel completely for short periods.
Engine Speed/Vehicle Speed/Fuel Disable Mode
The ECM monitors engine speed. It turns off the fuel
injectors when the engine speed increase above 6400
RPM. The fuel injectors are turned back on when
engine speed decreases below 6150 RPM.

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 preven
t
engine flooding.

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). I
t
calculates the air/fuel ratio based on inputs from the TP,
ECT, and MAF 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.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-57
Starting Mode
When the ignition is first turned "ON," the ECM
energizes the fuel pump relay for two seconds to allo
w
the fuel pump to build up pressure. The ECM then
checks the engine coolant temperature (ECT) senso
r
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.

Fuel Metering System Components
The fuel metering system is made up of the following
parts.

Fuel injector

Throttle Body

Fuel Rail

Fuel Pressure regulator

ECM

Crankshaft position (CKP) sensor

Camshaft position (CMP) sensor

Idle air control valve

Fuel pump

Fuel Injector
The sequential multi-port fuel injection fuel injector is a
solenoid operated device controlled by the ECM. The
ECM energizes the solenoid, which opens a valve to
allow fuel delivery.
The fuel is injected under pressure in a conical spray
pattern at the opening of the intake valve. Excess fuel
not used by the injectors passes through the fuel
pressure regulator before being returned to the fuel
tank.

Fuel Pressure Regulator
The fuel pressure regulator is a diaphragm-operated
relief valve mounted on the fuel rail with fuel pump
pressure on one side and manifold pressure on the
other side. The fuel pressure regulator maintains the
fuel pressure available to the injector at three times
barometric pressure adjusted for engine load. It may be
serviced separate.
If the pressure is too low, poor performance and a DTC
P0131, P0151, P0171, P0174, P1171 or P1174 will be
the result. If the pressure is too high, excessive odo
r
and/or a DTC P0132, P0152, P0172 or P0175 will be
the result. Refer to Fuel System Diagnosisfo
r
information on diagnosing fuel pressure conditions.
Fuel Rail
The fuel rail is mounted to the top of the engine and
distributes fuel to the individual injectors. Fuel is
delivered to the fuel inlet tube of the fuel rail by the fuel
lines. The fuel goes through the fuel rail to the fuel
pressure regulator. The fuel pressure regulato
r
maintains a constant fuel pressure at the injectors.
Remaining fuel is then returned to the fuel tank.







055RV009
Fuel Pump Electrical Circuit
When the key is first turned "ON," the ECM energizes
the fuel pump relay for two seconds to build up the fuel
pressure quickly. If the engine is not started within two
seconds, the ECM shuts the fuel pump off and waits
until the engine is cranked. When the engine is cranked
and the 58 X crankshaft position signal has been
detected by the ECM, the ECM supplies 12 volts to the
fuel pump relay to energize the electric in-tank fuel
pump.
An inoperative fuel pump will cause a "no-start"
condition. A fuel pump which does not provide enough
pressure will result in poor performance.

Camshaft Position (CMP) Sensor Signal
The ECM uses this signal to determine the position o
f
the number 1 piston during its power stroke, allowing
the ECM to calculate true sequential multiport fuel
injection. Loss of this signal will set a DTC P0341. If the
CMP signal is lost while the engine is running, the fuel
injection system will shift to a calculated sequential fuel
injection based on the last fuel injection pulse, and the
engine will continue to run. The engine can be restarted
and will run in the calculated sequential mode as long
as the fault is present, with a 1-in-6 chance of being
correct.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-79
TYPICAL SCAN DATA & DEFINITIONS (ENGINE DATA)
Use the typical values table only after the On-Board Diagnostic System check has been completed, no DTC(s) were noted, and you have determined that the On-Board
Diagnostic are functioning properly.
Tech2 values from a properly running engine may be used for comparison with the engine you are diagnosing.
Condition : Vehicle stopping, engine running, air conditioning off & after warm-up (Coolant temperature approximately 80
C)

Tech 2
Parameter
Units Idle 2000rpm Definitions
1 Ignition Voltage V 10.0  14.5 10.0  14.5 This displays the system voltage measured by the ECM at ignition feed.
2 Engine Speed rpm 710  860 1950  2050 The actual engine speed is measured by ECM from the CKP sensor 58X signal.
3 Desired Idle
Speed rpm 750  770 750  770 The desired engine idle speed that the ECM commanding.
The ECM compensates for various engine loads.
4 Engine Coolant
Temperature
C or
F 80  90 (

) 80  90 (

) The ECT is measured by ECM from ECT sensor output voltage.
When the engine is normally warm upped, this data displays approximately 80 °C or
more.
5 Start Up ECT
(Engine Coolant
Temperature)
C or
F Depends on ECT
at start-up
Depends on ECT
at start-up
Start-up ECT is measured by ECM from ECT sensor output voltage when engine is
started.
6 Intake Air
Temperature

C or
F Depends on
ambient temp.
Depends on
ambient temp.
The IAT is measured by ECM from IAT sensor output voltage.
This data is changing by intake air temperature.
7 Throttle Position % 0 4  6 Throttle position operating angle is measured by the ECM from throttle position
output voltage.
This should display 0% at idle and 99  100% at full throttle.
8 Throttle Position
Sensor V 0.4  0.7 0.6  0.8 The TPS output voltage is displayed.
This data is changing by accelerator operating angle.
9 Mass Air Flow g/s 5.0  8.0 13.0  16.0 This displays intake air amount.
The mass air flow is measured by ECM from the MAF sensor output voltage.
10 Air Fuel Ratio 14.7:1 14.7:1 This displays the ECM commanded value.
In closed loop, this should normally be displayed around 14.2:1  14.7:1.
11 Idle Air Control Steps 10  20 20  30 This displays the ECM commanded position of the idle air control valve pintle.
A larger number means that more air is being commanded through the idle air
passage.
12 EGR Valve V 0.00 0.00  0.10 The EGR position sensor output voltage is displayed.
This data is changing by EGR valve solenoid operating position.
13 Desired EGR
Opening V 0.00 0.05  1.10 The ECM commanded EGR position sensor voltage is displayed.
According to the current position, ECM changes EGR valve solenoid operating
position to meet the desired position.
14 EGR Valve On
Duty % 0 32 – 38 This displays the duty signal from the ECM to control the EGR valve.
15 Engine Load % 2  7 8  15 This displays is calculated by the ECM form engine speed and MAF sensor reading.
Engine load should increase with an increase in engine speed or air flow amount.
16 B1 Fuel System
Status Open Loop/ Close
Loop Close Loop Close Loop
17 B2 Fuel System
Status Open Loop/ Close
Loop Close Loop Close Loop
When the engine is first started the system is in "Open Loop" operation.
In "Open Loop", the ECM ignores the signal from the oxygen sensors.
When various conditions (ECT, time from start, engine speed & oxygen sensor
output) are met, the system enters "Closed Loop" operation.
In "Closed Loop", the ECM calculates the air fuel ratio based on the signal from the
oxygen sensors.
18 Fuel Trim
Learned (Bank 1) Yes/No Yes Yes
19 Fuel Trim
Learned (Bank 2) Yes/No Yes Yes
When conditions are appropriate for enabling long term fuel trim corrections, fuel trim
learn will display "Yes".
This indicates that the long term fuel trim is responding to the short term fuel trim.
If the fuel trim lean displays "No", then long term fuel trim will not respond to changes
in short term fuel trim.
20 Injection Pulse
Bank 1 ms 2.0  4.0 2.0  4.0
21 Injection Pulse
Bank 2 ms 2.0  4.0 2.0  4.0
This displays the amount of time the ECM is commanding each injector On during
each engine cycle.
A longer injector pulse width will cause more fuel to be delivered. Injector pulse width
should increase with increased engine load.
22 Spark Advance °CA 10  15 35  42 This displays the amount of spark advance being commanded by the ECM.

6E-80 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Tech 2
Parameter
Units Idle 2000rpm Definitions
23 A/C Request (Air
Conditioning) On/Off Off Off This displays the air conditioner request signal. This should display "On" when the air
conditioner switch is switched on.
24 A/C Clutch On/Off Off Off This displays whether the ECM has commanded the A/C compressor clutch "On" or
"Off".
25 EVAP Purge
Solenoid
(Evaporative
Emission) % 50
80 0 This displays the duty signal from the ECM to control the canister purge solenoid
valve.
26 Fuel Trim Cell 49
52 13
17 This displays dependent on engine speed and MAF sensor reading.
A plot of engine speed versus MAF amount is divided into the cells.
Fuel trim cell indicates which cell is currently active.
27 Fuel Pump On/Off On On This displays operating status for the fuel pump main relay.
This should display "On" when the key switch is turned on and while engine is
running.
28 Deceleration Fuel
Cutoff Active/ Inactive Inactive Inactive The ECM will command the deceleration fuel mode when it detects a closed throttle
position while the vehicle is traveling.
While in decreasing fuel mode, the ECM will decrease the amount of fuel delivered
by entering open loop and decreasing the injector pulse width.
29 Power Enrichment Yes/No No No The ECM will command power enrichment mode "Yes" when a large increase in
throttle position and load is detected.
While in power enrichment mode, the ECM will increase the amount of fuel delivered
by entering open loop and increasing the injector pulse width.
30 Vehicle Speed km/h or mph 0 0 This displays vehicle speed.
The vehicle speed is measured by ECM from the vehicle speed sensor.
31 Cam Signal Present/ Missing Present Present This displays input signal from the camshaft position sensor.
When the correct pulse is generated, signal is received.
32 PSP Switch
(Power Steering
Pressure) Normal Pressure /
High Pressure Normal PressureNormal PressureThis displays the power steering pressure signal.
This should display "High Pressure" when the steering is steered.
33 Security Code
Status Programmable/
Not
Programmable Programmable Programmable This should display "Programmable" when the correct security code & secret code
are programmed.
34 Security Code Okay/ Not Okay Okay Okay This should display "Okay" when the security code is correctly accepted.
35 Immobilizer
System Normal /
Abnormal Normal Normal This should display "Normal" when the immobilizer is correctly operated.
36 Malfunction
Indicator Lamp On/Off Off Off This displays operating status for the Check Engine Lamp.
This should display "On" when the Check Engine Lamp is turned on.
37 Time From Start   This displays the engine time elapsed since the engine was started.
If the engine is stopped, engine run time will be reset to 00:00:00

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-81
TYPICAL SCAN DATA & DEFINITIONS (O2 SENSOR DATA)
Use the typical values table only after the On-Board Diagnostic System check has been completed, no DTC(s) were noted, and you have determined that the On-Board
Diagnostic are functioning properly.
Tech2 values from a properly running engine may be used for comparison with the engine you are diagnosing.
Condition : Vehicle stopping, engine running, air conditioning off & after warm-up (Coolant temperature approximately 80
C)

Tech 2
Parameter
Units Idle 2000rpm Definitions
1 Ignition Voltage V 10.0  14.5 10.0  14.5 This displays the system voltage measured by the ECM at ignition feed.
2 Engine Speed rpm 710  860 1950  2050 The actual engine speed is measured by ECM from the CKP sensor 58X signal.
3 Desired Idle
Speed rpm 750  770 750  770 The desired engine idle speed that the ECM commanding.
The ECM compensates for various engine loads.
4 Engine Coolant
Temperature
C or
F 80  90 (
C) 80  90 (
C) The ECT is measured by ECM from ECT sensor output voltage.
When the engine is normally warm upped, this data displays approximately 80 °C or
more.
5 Start Up ECT
(Engine Coolant
Temperature)
C or
F Depends on ECT
at start-up
Depends on ECT
at start-up
Start-up ECT is measured by ECM from ECT sensor output voltage when engine is
started.
6 Throttle Position % 0 4  6 Throttle position operating angle is measured by the ECM from throttle position
output voltage.
This should display 0% at idle and 99  100% at full throttle.
7 Throttle Position
Sensor V 0.4  0.7 0.6  0.8 The TPS output voltage is displayed.
This data is changing by accelerator operating angle.
8 Mass Air Flow g/s 5.0  8.0 13.0  16.0 This displays intake air amount.
The mass air flow is measured by ECM from the MAF sensor output voltage.
9 Air Fuel Ratio 14.7:1 14.7:1 This displays the ECM commanded value. In closed loop, this should normally be
displayed around 14.2:1  14.7:1.
10 Engine Load % 2  7 8  15 This displays is calculated by the ECM form engine speed and MAF sensor reading.
Engine load should increase with an increase in engine speed or air flow amount.
11 B1 Fuel System
Status Open Loop/ Close
Loop Close Loop Close Loop
12 B2 Fuel System
Status Open Loop/ Close
Loop Close Loop Close Loop
When the engine is first started the system is in "Open Loop" operation.
In "Open Loop", the ECM ignores the signal from the oxygen sensors.
When various conditions (ECT, time from start, engine speed & oxygen sensor
output) are met, the system enters "Closed Loop" operation.
In "Closed Loop", the ECM calculates the air fuel ratio based on the signal from the
oxygen sensors.
13 B1S1 O2 Sensor
(Bank1 Sensor 1)
mV 50  950 50 950
14 B2S1 O2 Sensor
(Bank2 Sensor 1)
mV 50  950 50  950
This displays the exhaust oxygen sensor output voltage.
Should fluctuate constantly within a range between 10mV (lean exhaust) and
1000mV (rich exhaust) while operating in closed loop.
15 B1 O2 Sensor
Ready (Bank 1)
Yes/No Yes Yes
16 B2 O2 Sensor
Ready (Bank 2)
Yes/No Yes Yes
This displays the status of the exhaust oxygen sensor.
This display will indicate "Yes" when the ECM detects a fluctuating oxygen sensor
output voltage sufficient to allow closed loop operation.
This will not occur unless the oxygen sensor is warmed up.
17 B1 Long Term
Fuel Trim (Bank
1)
% -10  20 -10  20
18 B2 Long Term
Fuel Trim (Bank
2)
% -10  20 -10  20
The long term fuel trim is delivered from the short term fuel term values and
represents a long term correction of fuel delivery for bank in question.
A value of 0% indicates that fuel delivery requires no compensation to maintain the
ECM commanded air fuel ratio.
A negative value indicates that the fuel system is rich and fuel delivery is being
reduced (decreased injector pulse width).
A positive value indicates that a lean condition exists and the ECM is compensating
by add fuel (increased injector pulse width).
Because long term fuel trim tends to follow short term fuel trim, a value in the
negative range due to canister purge at idle should not be considered unusual.
Excessive long term fuel trim values may indicate an rich or lean condition.

6E-106 3.5L ENGINE DRIVEABILITY AND EMISSIONS

FUEL INJECTOR COIL TEST
PROCEDURE AND FUEL INJECTOR
BALANCE TEST PROCEDURE




Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2.
Relieve the fuel pressure by connecting the 5–
8840–0378–0 Fuel Pressure Gauge to the fuel
pressure connection on the fuel rail.
CAUTION: In order to reduce the risk of fire and
personal injury, wrap a shop towel around the fuel
pressure connection. The towel will absorb any fuel
leakage that occurs during the connection of the
fuel pressure gauge. Place the towel in an approved
container when the connection of the fuel pressure
gauge is complete.

Place the fuel pressure gauge bleed hose in an
approved gasoline container.

With the ignition switch “OFF," open the valve on
the fuel pressure gauge.


3.
Record the lowest voltage displayed by the DVM
after the first second of the test. (During the first
second, voltage displayed by the DVM may be
inaccurate due to the initial current surge.)

Injector Specifications:

Resistance Ohms Voltage Specification at
10

C

35
C (50
F

95
F)
11.8 – 12.6 5.7 – 6.6


The voltage displayed by the DVM should be within
the specified range.
 The voltage displayed by the DVM may increase
throughout the test as the fuel injector windings
warm and the resistance of the fuel injecto
r
windings changes.
 An erratic voltage reading (large fluctuations in
voltage that do not stabilize) indicates an
intermittent connection within the fuel injector.
5.
Injector Specifications:




Highest Acceptable
Voltage Reading
Above/Below 35

C/10
C
(95

F/50
F) Acceptable Subtracted
Value
9.5 Volts 0.6 Volts
7.
The Fuel Injector Balance Test portion of this chart
(Step 7 through Step 11) checks the mechanical
(fuel delivery) portion of the fuel injector. An engine
cool-down period of 10 minutes is necessary in
order to avoid irregular fuel pressure readings due
to “Hot Soak" fuel boiling.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E -107

Injector Coil Test Procedure (Steps 1-6) and Injector Balance Test Procedure
(Steps 7-11)



CYLINDER 1 2 3 4 5 6
1st Reading (1) 296 kPa
(43 psi) 296 kPa
(43 psi) 296 kPa
(43 psi) 296 kPa
(43 psi) 296 kPa
(43 psi) 296 kPa
(43 psi)
2nd Reading (2) 131 kPa
(19 psi) 117 kPa
(17 psi) 124 kPa
(18 psi) 145 kPa
(21 psi) 131 kPa
(19 psi) 130 kPa
(19 psi)
Amount of Drop
(1st Reading–2nd Reading) 165 kPa
(24 psi) 179 kPa
(26 psi) 172 kPa
(25 psi) 151 kPa
(22 psi) 165 kPa
(24 psi) 166 kPa
(24 psi)
Av.drop = 166 kPa/24 psi

10 kPa/1.5 psi
= 156- 176 kPa or
22.5- 25.5 psi OK Faulty, Rich
(Too Much
Fuel Drop) OK Faulty, Lean
( Too Little
Fuel Drop) OK OK

NOTE: These figures are examples only.

6E-108 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Injector Coil Test Procedure (Steps 1-6) and Injector Balance Test Procedure
(Steps 7-11)

Step Action Value(s) YES NO
1
Was the “On-Board Diagnostic (OBD) System Check"
performed?
— Go to Step 2 Go to OBD
System Check
2 1. Turn the engine “OFF."
In order to prevent flooding of a single cylinder and
possible engine damage, relieve the fuel pressure
before performing the fuel injector coil test procedure.
2. Relieve the fuel pressure. Refer to Test
Description Number 2.
3. Connect the 5–8840–2618–0 Fuel Injector Tester
to B+ and ground, and to the 5–8840–2635–0
Injector Switch Box.
4. Connect the injector switch box to the gray fuel
injector harness connector located at the rear of
the air cleaner assembly.
5. Set the amperage supply selector switch on the
fuel injector tester to the “Coil Test" 0.5 amp
position.
6. Connect the leads from the Digital Voltmeter
(DVM) to the injector tester. Refer to the
illustrations associated with the test description.
7. Set the DVM to the tenths scale (0.0).
8. Observe the engine coolant temperature.
Is the engine coolant temperature within the specified
values? 10
C (50
F) to
35
C (95
F) Go to Step 3 Go to Step 5
3
1. Set injector switch box injector #1.
2. Press the “Push to Start Test" button on the fuel
injector tester.
3. Observe the voltage reading on the DVM.
Important: The voltage reading may rise during the
test.
4. Record the lowest voltage observed after the first
second of the test.
5. Set the injector switch box to the next injector and
repeat steps 2, 3, and 4.
Did any fuel injector have an erratic voltage reading
(large fluctuations in voltage that did not stabilize) or a
voltage reading outside of the specified values? 5.7-6.6 V Go to Step 4 Go to Step 7
4 Replace the faulty fuel injector(s). Refer to Fuel
Injector.
Is the action complete? — Go to Step 7 —