Accelerator Pedal Position ISUZU TF SERIES 2004 User Guide

6E–372 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
17 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Was the problem solved?—Verify repair Go to Step 18
18 Check the TPS 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 19
19 Substitute a known good TPS and recheck.
Was the problem solved?—Go to Step 20Go to Step 36
20 Replace the TPS.
Is the action complete?—Veri fy repai r—
21 Remove the CKP sensor from the flywheel housing
and check for the following conditions.
Objects sticking the CKP sensor.
Objects sticking the CKP sensor pulser.
If a problem is found, repair as necessary.
Was the problem found? —Verify repair Go to Step 22
22 Check the CKP 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 23
23 Substitute a known good CKP sensor and recheck.
Was the problem solved?—Go to Step 24Go to Step 25
24 Replace the CKP sensor.
Is the action complete?—Veri fy repai r— Step Action Value(s) Yes No

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–377
SURGES AND/OR CHUGS SYMPTOM
DEFINITIONS: Engine power variation under steady
throttle or cruise. Feels like the vehicle speeds up and
slows down with no charge in the accelerator pedal.
time rpm
Su rge
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?—Verify repair Go to Step 3
3 Was a visually/physical check performed?
—Go to Step 4Go to Visual /
physical Check
4 Is the customer using the incorrect fuel type? Diesel fuel
onlyReplace with
diesel fuel Go to Step 5
5 Visually/physically inspect for the following conditions.
Restrict air intake system. Check for a restricted air
filter element, or foreign objects blocking the air
intake system
Check for objects blocking or ex cessive deposits in
the throttle bore and on the throttle plate
Check for a condition that causes a large vacuum
leak, such as an incorrectly installed or faulty
crankcase ventilation hose.
Restrict air intake system at the turbocharger.
Check for objects blocking the turbocharger
compressor wheel or turbine shaft sticking.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 6
6 Check the ECM & PSG grounds to verify that they are
clean and tight. Refer to the ECM wiring diagrams.
Was a problem found?—Verify repair Go to Step 7
7 1. Using the Tech 2, ignition “On” and engine “Run”.
2. Monitor the “A/C Information Switch” in the data
display.
Does the Tech 2 indicate correct “A/C Information
Switch” status depending on A/C switch position?
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 8

6E–378 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
8 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 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
12 Substitute a known good MAF & IAT sensor assembly
and recheck.
Was the problem solved?—Go to Step 13Go to Step 29
13 Replace the MAF & IAT sensor assembly.
Is the action complete?—Veri fy repai r—
14 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
Does the Tech 2 indicate correct “Pedal/Throttle
Position” from 0% to 100% and correct “Idle Switch”
status depending on accelerator pedal operation?—Go to Step 19Go to Step 15
15 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Was the problem solved?—Verify repair Go to Step 16
16 Check the TPS 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 17
17 Substitute a known good TPS and recheck.
Was the problem solved?—Go to Step 18Go to Step 29
18 Replace the TPS.
Is the action complete?—Veri fy repai r— Step Action Value(s) Yes No

6E–384 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
8 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 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
12 Substitute a known good MAF & IAT sensor assembly
and recheck.
Was the problem solved?—Go to Step 13Go to Step 31
13 Replace the MAF & IAT sensor assembly.
Is the action complete?—Veri fy repai r—
14 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
Does the Tech 2 indicate correct “Pedal/Throttle
Position” from 0% to 100% and correct “Idle Switch”
status depending on accelerator pedal operation?—Go to Step 19Go to Step 15
15 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Was the problem solved?—Verify repair Go to Step 16
16 Check the TPS 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 17
17 Substitute a known good TPS and recheck.
Was the problem solved?—Go to Step 18Go to Step 31
18 Replace the TPS.
Is the action complete?—Veri fy repai r— Step Action Value(s) Yes No

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–391
16 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
Does the Tech 2 indicate correct “Pedal/Throttle
Position” from 0% to 100% and correct “Idle Switch”
status depending on accelerator pedal operation?—Go to Step 21Go to Step 17
17 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Was the problem solved?—Verify repair Go to Step 18
18 Check the TPS 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 19
19 Substitute a known good TPS and recheck.
Was the problem solved?—Go to Step 20Go to Step 31
20 Replace the TPS.
Is the action complete?—Veri fy repai r—
21 Remove the CKP sensor from the flywheel housing
and check for the following conditions.
Objects sticking the CKP sensor.
Objects sticking the CKP sensor pulser.
If a problem is found, repair as necessary.
Was the problem found? —Verify repair Go to Step 22
22 Check the CKP 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 23
23 Substitute a known good CKP sensor and recheck.
Was the problem solved?—Go to Step 24Go to Step 25
24 Replace the CKP sensor.
Is the action complete?—Veri fy repai r— Step Action Value(s) Yes No

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–397
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
12 Substitute a known good MAF & IAT sensor assembly
and recheck.
Was the problem solved?—Go to Step 13Go to Step 29
13 Replace the MAF & IAT sensor assembly.
Is the action complete?—Veri fy repai r—
14 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
Does the Tech 2 indicate correct “Pedal/Throttle
Position” from 0% to 100% and correct “Idle Switch”
status depending on accelerator pedal operation?—Go to Step 19Go to Step 15
15 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Was the problem solved?—Verify repair Go to Step 16
16 Check the TPS 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 17
17 Substitute a known good TPS and recheck.
Was the problem solved?—Go to Step 18Go to Step 30
18 Replace the TPS.
Is the action complete?—Veri fy repai r— Step Action Value(s) Yes No

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–403
13 1. Using the Tech 2, ignition “On” and engine “Run”.
2. Monitor the “A/C Information Switch” in the data
display.
Does the Tech 2 indicate correct “A/C Information
Switch” status depending on A/C switch position?
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 14
14 Visually/physically inspect for the following conditions.
Restrict air intake system. Check for a restricted air
filter element, or foreign objects blocking the air
intake system
Check for objects blocking or ex cessive deposits in
the throttle bore and on the throttle plate
Check for a condition that causes a large vacuum
leak, such as an incorrectly installed or faulty
crankcase ventilation hose.
Restrict air intake system at the turbocharger.
Check for objects blocking the turbocharger
compressor wheel or turbine shaft sticking.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 15
15 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 16
16 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 31Go to Step 17
17 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 22Go to Step 18
18 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 19
19 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 20 Step Action Value(s) Yes No

6E–404 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
20 Substitute a known good MAF & IAT sensor assembly
and recheck.
Was the problem solved?—Go to Step 21Go to Step 31
21 Replace the MAF & IAT sensor assembly.
Is the action complete?—Veri fy repai r—
22 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
Does the Tech 2 indicate correct “Pedal/Throttle
Position” from 0% to 100% and correct “Idle Switch”
status depending on accelerator pedal operation?—Go to Step 27Go to Step 23
23 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Pedal/Throttle Position” and “Idle
Switch” in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Was the problem solved?—Verify repair Go to Step 24
24 Check the TPS 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 25
25 Substitute a known good TPS and recheck.
Was the problem solved?—Go to Step 26Go to Step 31
26 Replace the TPS.
Is the action complete?—Veri fy repai r—
27 Remove the injection nozzles from the engine and
check for the following conditions.
Improper splay condition.
Operating pressure is incorrect.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
injection nozzle
and verify repair Go to Step 28 Step Action Value(s) Yes No
1st Stage 2nd Sta ge
4JA1-TCApproximatly
19.0 MpaApprox ima tly
33.5 Mpa
4JH1-TCApproximatly
19.5 MpaApprox ima tly
33.8 Mpa

6E-52 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Mass Air Flow (MAF) Sensor & Intake Air
Temperature (IAT) Sensor





The MAF sensor is part of the intake air system.
It is fitted between the air cleaner & throttle body and
measure the mass air flowing into the engine.
The MAF sensor uses a hot wire element to determine
the amount of air flowing into the engine. (The wire
temperature reaches to 170 - 300C)
The MAF sensor assembly consist of a MAF senso
r
element and an intake air temperature sensor that are
both exposed to the air flow to be measured.
The MAF sensor element measures the partial air mass
through a measurement duct on the sensor housing.
Using calibration, there is an extrapolation to the entire
mass air flow to the engine.


















The IAT sensor is a thermistor. A temperature changes
the resistance value. And it changes voltage. In othe
r
words it measures a temperature value. Low air
temperature produces a high resistance.
The ECM supplies 5 volts signal to the IAT senso
r
through resisters in the ECM and measures the voltage.
The signal voltage will be high when the air temperature
is cold, and it will be low when the air temperature is
hot. Throttle Position Sensor (TPS)





1
2
(1) Throttle Position Sensor (TPS)
(2) Idle Air Control Valve (IACValve)


The TPS is a potentiometer connected to throttle shaf
t
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 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.
Charac teristic of IA T Sens or
10 100 1000 10000 100000-3010 50 90130Temper atur e (

)
Resistance (Ω)

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.