check engine ISUZU TF SERIES 2004 Workshop Manual

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-345
HESITATION, SAG, STUMBLE SYMPTOM
DEFINITIONS: Momentary lack of response as the
accelerator is pushed down. Can occur at any vehicle
speed. Usually most pronounced when first trying to
make the vehicle move, as from a stop sign. May cause
the engine to stall if severe enough.




time rpm
Sug
Hesitation Stumble



Step Action Value (s) Yes No
1
Was the "On-Board Diagnostic (OBD) System Check"
performed?
- Go to Step 2 Go 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 4 Go to Visual /
physical Check.
4
Check the fuel quality.
Is the customer using improper fuel or degraded fuel?
- Replace fuel Go to Step 5
5
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 7 Go to Step 6

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

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-347
Step Action Value (s) Yes No
13
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 15
14
Check items that can cause the engine to run lean.
Refer to DTC P0171 "O2 Sensor System Too Lean
(Bank 1)" or DTC P0174 "O2 Sensor System Tool
Lean (Bank 2)".
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
Check the ignition coils for cracks or carbon tracking.
If a problem is found, repair as necessary.
Was a problem found?
- Verify repair Go to Step 17
17
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 18
18
1. Check the injector connectors.
2. If any of the connectors are connected at an
improper cylinder, connect as necessary.
Was a problem found?
- Verify repair Go to Step 19
19
Check the ECM grounds to verify that they are clean
and tight. Refer to the ECM wiring diagrams.
Was a problem found?
- Verify repair Go to Step 20
20
Visually/physically check the vacuum hose for splits,
kinks and proper connections and routing.
Was a problem found?
- Verify repair Go to Step 21
21
Check the exhaust system for a possible restriction:

Damaged or collapsed pipes.

Internal muffler failure.
Was a problem found?
- Verify repair Go to Step 22

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-349
CUTS OUT, MISSES SYMPTOM

DEFINITIONS: Steady pulsation or jerking that follows
engine speed; usually more pronounced as engine load
increases.




time rpm



Step Action Value (s) Yes No
1
Was the "On-Board Diagnostic (OBD) System Check"
performed?
- Go to Step 2 Go 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 4 Go to Visual /
physical Check.
4
Check the ECM grounds to verify that they are clean
and tight. Refer to the ECM wiring diagrams.
Was a problem found?
- Verify repair Go to Step 5
5
Check the CKP sensor signal or installation condition.
Refer to DTC P0336 "Crankshaft Position Sensor
Circuit Range/Performance" and DTC P0337
"Crankshaft Position Sensor Circuit No Signal".
Was a problem found?
- Verify repair Go to Step 6
6
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 7 Go to Step 8
7
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 9
8
Check items that can cause the engine to run lean.
Refer to DTC P0171 "O2 Sensor System Too Lean
(Bank 1)" or DTC P0174 "O2 Sensor System Tool
Lean (Bank 2)".
Was a problem found?
- Verify repair Go to Step 9

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-351
Step Action Value (s) Yes No
17
Check for the following engine mechanical problems
(refer to Engine Mechanical Section):

Low compression. -Leaking cylinder head gaskets.

Worn camshaft. -Sticking or leaking valves.

Valve timing. -Broken valve springs.

Camshaft drive belt slipped or stripped.
Was a problem found?
- Verify repair Go to Step 18
18
1. Check for faulty engine mounts.
2. If a problem is found, repair as necessary.
Was a problem found?
- Verify repair Go to Step 19
19
1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection.

Tech 2 data.

All electrical connections within a suspected circuit
and/or system.
Was a problem found?
- Verify repair Go to Step 20
20
Is the ECM programmed with the latest software
release?
If not, download the latest software to the ECM using
the "SPS (Service Programming System)".
Was the problem solved?
- Verify repair Go to Step 21
21
Replace the ECM.
Is the action complete?
IMPORTANT: The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. Following
ECM programming, the immobilizer system (if
equipped) must be linked to the ECM. Refer to section
11 “Immobilizer System-ECM replacement” for the
ECM/Immobilizer linking procedure.
- Verify repair -

6E-352 3.5L ENGINE DRIVEABILITY AND EMISSIONS
LACK OF POWER, SLUGGISH OR SPONGY SYMPTOM
DEFINITIONS: Engine delivers less than expected
power. Attempting part-throttle acceleration results in
little or no increase in vehicle speed.



Step Action Value (s) Yes No
1
Was the "On-Board Diagnostic (OBD) System Check"
performed?
- Go to Step 2 Go 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 4 Go to Visual /
physical
Check.
4
1. Remove and check the air filter element for dirt or
restrictions.
2. Replace the air filter element if necessary.
Was a repair required?
- Verify repair Go to Step 5
5
Check the fuel quality.
Is the customer using improper fuel or degraded fuel?
- Replace fuel Go to Step 6
6
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 8 Go to Step 7

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

6E-354 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
15
Check items that can cause the engine to run lean. Refer to
DTC P0171 "O2 Sensor System Too Lean (Bank 1)" or DTC
P0174 "O2 Sensor System Tool Lean (Bank 2)".
Was a problem found?
- Verify repair Go to Step 16
16
Check for proper ignition voltage output with the spark tester.
Was a problem found?
- Verify repair Go to Step 17
17
Check the ignition coils for cracks or carbon tracking. If a
problem is found, repair as necessary.
Was a problem found?
- Verify repair Go to Step 18
18
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 19
19
Visually/physically check the vacuum hose for splits, kinks and
proper connections and routing.
Was a problem found?
- Verify repair Go to Step 20
20
Check the exhaust system for a possible restriction:

Damaged or collapsed pipes.

Internal muffler failure.
Was a problem found?
- Verify repair Go to Step 21
21
Check the torque converter clutch (TCC) for proper operation
(if A/T model). If a problem is found, repair as necessary.
Was a problem found?
- Verify repair Go to Step 22
22
Check for the following engine mechanical problems (refer to
Engine Mechanical Section):

Low compression.

Leaking cylinder head gaskets.

Worn camshaft.

Sticking or leaking valves.

Valve timing.

Broken valve springs.

Camshaft drive belt slipped or stripped.
Was a problem found?
- Verify repair Go to Step 23
23
1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no malfunctions
have been found, review/inspect the following:

Visual/physical inspection.

Tech 2 data.

All electrical connections within a suspected circuit and/or
system.
Was a problem found?
- Verify repair Go to Step 24

6E-356 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DETONATION/SPARK KNOCK SYMPTOM
DEFINITIONS: A mild to sever ping, usually worse
under acceleration. The engine makes a shape metallic
knocking sound that changes with throttle opening.
Prolonged detonation may lead to complete engine
failure.



Step Action Value (s) Yes No
1
Was the "On-Board Diagnostic (OBD) System Check"
performed?
- Go to Step 2 Go 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 4 Go to Visual /
physical Check.
4
1. If Tech 2 readings are normal (refer to Typical Scan
Data Values) and there are no engine mechanical
faults, fill the fuel tank with a known quality
gasoline.
2. Re-evaluate the vehicle performance.
Is detonation present?
- Go to Step 5
Verify repair
5
Check for obvious overheating problems:

Low engine coolant.

Restricted air flow to radiator.

Incorrect coolant solution.
If a problem is found, repair as necessary.
Was a problem found?
- Verify repair Go to Step 6
6
1. Using a Tech 2, display the ECT sensor and IAT
sensor value.
2. Check the specified value or wire.
Was the problem found?
- Verify repair Go to Step 7