2004 ISUZU TF SERIES Accelerator Pedal Position

6E-338 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
7
1. Using the Tech 2, ignition "On" and engine "On".
2. Monitor the "Mass Air Flow" in the data display.
Does the Tech 2 indicate correct "Mass Air Flow" as
shown in the following graph, when engine speed is
increasing little by little?

Characteris tic of MAF Sens or -Ref erence (No Engine Load)-
0 5 10 15 20 25 30 35 40 45 50
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Eng i ne Speed ( r pm) ( T ech2 R eadi ng )
Mass Air Flow (g/s)
( T ec h2 R eadi ng)
- Go to Step 9 Go to Step 8
8
Remove the MAF & IAT sensor assembly and check
for the following conditions.

Objects blocking the air cleaner.

Objects blocking the MAF sensor.

Objects blocking the throttle valve.

Vacuum leaking at intake duct.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found? - Verify repair Refer to DTC
P0101 and Go to
Step 9
9
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
Does the Tech 2 indicate correct "Throttle Position"
from 0% to 100% depending on accelerator pedal
operation?

- Go to Step 11 Go to Step 10
10
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Is the action complete?
- Verify repair -
11
Check for the following conditions.

Objects blocking the throttle valve.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Go to Step 12

6E-342 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
6
Remove the MAF & IAT sensor assembly and check
for the following conditions.

Objects blocking the air cleaner.

Objects blocking the MAF sensor.

Objects blocking the throttle valve.

Vacuum leaking at intake duct.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Refer to DTC
P0101 and Go to
Step 7
7
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
Does the Tech 2 indicate correct "Throttle Position"
from 0% to 100% depending on accelerator pedal
operation?




- Go to Step 9 Go to Step 8
8
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Is the action complete?
- Verify repair -
9
Check for the following conditions.

Objects blocking the throttle valve.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Go to Step 10
10
Check the fuel control Heated Oxygen Sensor
(HO2S). When monitored on the Tech 2, the HO2S
should respond quickly to different throttle positions. If
it doesn't check for silicon or other contaminates from
fuel or use of improper sealant. The sensors may have
a white powdery coating. Silicon contamination sends
a rich exhaust signal which causes the ECM to
command and excessively lean air/fuel mixture.
Was a problem found?
- Verify repair Go to Step 11
11
Check the fuel pressure. Refer to 6E-116 Fuel System
Diagnosis.
Was a problem found?
- Verify repair Go to Step 12
12
Monitor "B1S1 (Bank 1 Sensor 1) Status" and "B2S1
(Bank 2 Sensor 1) Status" on the Tech 2.
Is the "B1S1 (Bank 1 Sensor 1) Status" or "B2S1
(Bank 2 Sensor 1) Status" in the rich condition?
- Go to Step 13 Go to Step 14

6E-346 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
6
Remove the MAF & IAT sensor assembly and check
for the following conditions.

Objects blocking the air cleaner.

Objects blocking the MAF sensor.

Objects blocking the throttle valve.

Vacuum leaking at intake duct.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Refer to DTC
P0101 and Go to
Step 7
7
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
Does the Tech 2 indicate correct "Throttle Position"
from 0% to 100% depending on accelerator pedal
operation?




- Go to Step 9 Go to Step 8
8
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Is the action complete?
- Verify repair -
9
Check for the following conditions.

Objects blocking the throttle valve.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Go to Step 10
10
Check the fuel control Heated Oxygen Sensor
(HO2S). When monitored on the Tech 2, the HO2S
should respond quickly to different throttle positions. If
it doesn't check for silicon or other contaminates from
fuel or use of improper sealant. The sensors may have
a white powdery coating. Silicon contamination sends
a rich exhaust signal which causes the ECM to
command and excessively lean air/fuel mixture.
Was a problem found?
- Verify repair Go to Step 11
11
Check the fuel pressure. Refer to Fuel System
Diagnosis.
Refer to 6E-116 page.
Diagnosis. Was a problem found?
- Verify repair Go to Step 12
12
Monitor "B1S1 (Bank 1 Sensor 1) Status" and "B2S1
(Bank 2 Sensor 1) Status" on the Tech 2.
Is the "B1S1 (Bank 1 Sensor 1) Status" or "B2S1
(Bank 2 Sensor 1) Status" in the rich condition?
- Go to Step 13 Go to Step 14

6E-350 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
9
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
Does the Tech 2 indicate correct "Throttle Position"
from 0% to 100% depending on accelerator pedal
operation?
- Go to Step 11 Go to Step 10
10
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Is the action complete?
- Verify repair -
11
Check for the following conditions.

Objects blocking the throttle valve.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found? - Verify repair Go to Step 12
12
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 the IAC passage or
throttle bore, excessive 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/brake booster hose.
Was a problem found?
- Verify repair Go to Step 13
13
Perform the Injector Coil/Balance Test.
Refer to 6E-106 page
Was a problem found.
- Verify repair Go to Step 14
14
1. Check for fuel in the pressure regulator vacuum
hose.
2. If fuel is present, replace the fuel pressure regulator
assembly.
Was a problem found?
- Verify repair Go to Step 15
15
Check for proper ignition voltage output with the spark
tester.
Was a problem found?
- Verify repair Go to Step 16
16
1. Remove the spark plugs and check for gas or oil
fouling cracks, wear, improper gap, burned
electrodes, heavy deposits, or improper heat
range.
2. If spark plugs are fouled, the cause of fouling must
be determined before replacing the spark plugs.
Was a problem found?
- Verify repair Go to Step 17

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-353
Step Action Value (s) Yes No
7
Remove the MAF & IAT sensor assembly and check for the
following conditions.

Objects blocking the air cleaner.

Objects blocking the MAF sensor.

Objects blocking the throttle valve.

Vacuum leaking at intake duct.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Refer to DTC
P0101 and Go
to Step 8
8
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
Does the Tech 2 indicate correct "Throttle Position" from 0%
to 100% depending on accelerator pedal operation?

- Go to Step 10Go to Step 9
9
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
3. Adjust the accelerator cable or TPS within 0% to 100%.
Is the action complete?
- Verify repair -
10
Check for the following conditions.

Objects blocking the throttle valve.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Go to Step 11
11
Check the fuel control Heated Oxygen Sensor (HO2S). When
monitored on the Tech 2, the HO2S should respond quickly to
different throttle positions. If it doesn't check for silicon or other
contaminates from fuel or use of improper sealant. The
sensors may have a white powdery coating. Silicon
contamination sends a rich exhaust signal which causes the
ECM to command and excessively lean air/fuel mixture.
Was a problem found?
- Verify repair Go to Step 12
12
Check the fuel pressure. Refer to 6E-116 Fuel System
Diagnosis.
Was a problem found?
- Verify repair Go to Step 13
13
Monitor "B1S1 (Bank 1 Sensor 1) Status" and "B2S1 (Bank 2
Sensor 1) Status" on the Tech 2.
Is the "B1S1 (Bank 1 Sensor 1) Status" or "B2S1 (Bank 2
Sensor 1) Status" in the rich condition?
- Go to Step 14Go to Step 15
14
Check items that can cause the engine to run rich. Refer to
DTC P0172 "O2 Sensor System Too Rich (Bank 1)" or DTC
P0175 "O2 Sensor System Too Rich (Bank 2)".
Was a problem found?
- Verify repair Go to Step 16

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-357
Step Action Value (s) Yes No
7
1. Using the Tech 2, ignition "On" and engine "On".
2. Monitor the "Mass Air Flow" in the data display.
Does the Tech 2 indicate correct "Mass Air Flow" as
shown in the following graph, when engine speed is
increasing little by little?




Characteris tic of MAF Sens or -Ref erence (No Engine Load)-
0 5 10 15 20 25 30 35 40 45 50
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Eng i ne Speed ( r pm) ( T ech2 R eadi ng )
Mass Air Flow (g/s)
( T ec h2 R eadi ng)

- Go to Step 9 Go to Step 8
8
Remove the MAF & IAT sensor assembly and check
for the following conditions.

Objects blocking the air cleaner.

Objects blocking the MAF sensor.

Objects blocking the throttle valve.

Vacuum leaking at intake duct.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Refer to DTC
P0101 and Go to
Step 9
9
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
Does the Tech 2 indicate correct "Throttle Position"
from 0% to 100% depending on accelerator pedal
operation?




- Go to Step 11 Go to Step 10
10
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
3. Adjust the accelerator cable or TPS within 0% to
100%.
Is the action complete?
- Verify repair -
11
Check the fuel control Heated Oxygen Sensor
(HO2S). When monitored on the Tech 2, the HO2S
should respond quickly to different throttle positions. If
it doesn't check for silicon or other contaminates from
fuel or use of improper sealant. The sensors may have
a white powdery coating. Silicon contamination sends
a rich exhaust signal which causes the ECM to
command and excessively lean air/fuel mixture.
Was a problem found?
- Verify repair Go to Step 12

ENGINE MECHANICAL (C24SE) 6A-73




Oxygen Sensor (If applicable)
Removal
1. Remove wiring harness plug.
2. Remove oxygen sensor from the front exhaust pipe.


Tighten (Torque)
Oxygen sensor in exhaust pipe - 30 N

m (3.1 kgf

m)









Throttle Valve Position Sensor
Removal
1. Remove wiring harness connector.
2. Remove throttle valve position sensor.

Installation
1. Install throttle valve position sensor.
2. Install wiring harness connector.


Accelerator Pedal and Cable
Removal
1. Remove pad stopper from pedal stop bolt.





Installation
1. Install pad stopper.

Inspection
Ensure that accelerator pedal is fully in idle position and
accelerator level at engine is in closed position.

Pull outer sleeve of accelerator cable towards pedal and check
that clip on sleeve is in slot nearest to grommet.

Reposition clip if necessary, and check that full throttle and idle
positions are obtained at engine lever.

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)