check engine ISUZU TF SERIES 2004 Workshop Manual

6E–376 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
33 Check the inlet/ex haust valve clearance for each
valves.
Are the valve clearances within the specified value?
0.4mm at cold
(In/Ex ) Go to Step 34Adjust and
verify repair
34 1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
followi ng:
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 35
35 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 36
36 Substitute a known good ECM and recheck.
Was the problem solved?
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. —Go to Step 37Go to Step 38
37 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.—Veri fy repai r—
38 Replace the injection pump assembly.
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

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–379
19 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 20
20 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 21
21 Substitute a known good CKP sensor and recheck.
Was the problem solved?—Go to Step 22Go to Step 23
22 Replace the CKP sensor.
Is the action complete?—Veri fy repai r—
23 1. Using the Tech 2 and ignition “On” and engine
“Run”.
2. Monitor the following parameters in the data
display.
“Desired Injection Quantity” & “Injection Quantity”
“Desired Injection Start” & “Actual Injection Start”
Are the large gap or unstable parameter displayed
between “Desired” and “Actual”?
—Go to Step 25Go to Step 24 Step Action Value(s) Yes No
When idling or part-throttle When accelerated


HighDesired
Lo w
Ti m e Actu a l
High
LowDesir ed
Actu a l
Ti m e

6E–380 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
24 Using the Tech 2 or the vacuum pump and check the
EGR valve operation for the following condition
through the small window.
ÅERestrict shaft movement. Check for objects sticking
the shaft, broken diaphragm or ex cessive carbon
deposit.
Tech 2:
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"EGR Solenoid Test" in the "Solenoid".
3. Operate the Tech 2 in accordance with procedure.
Solenoid 95%: EGR Valve Open
Solenoid 5%: EGR Valve Close
Vacuum Pump:
1. Using the vacuum pump. Disconnect the original
vacuum hose and connect the hose to the EGR
valve.
2. Apply vacuum pressure.
Vacuum Apply: EGR Valve Open
Vacuum Release: EGR Valve Close
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 25
25 Visually/physically inspect for the following conditions.
Restrict fuel supply system. Check for a pinched
fuel hose/pipe.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 26
26 Replace the fuel filter.
Was the problem solved?—Verify repair Go to Step 27 Step Action Value(s) Yes No

Vacuum Pump Small Window

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–381
27 Remove the eye bolt with gauze filter from the
injection pump and check for the following conditions.
Objects blocking at the gauze filter. Check for a
condition that causes contaminated fuel, such as
the customer is using an aftermarket fuel filter or
ex tended maintenance interval.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
eye bolt with
gauze filter and
verify repair Go to Step 28
28 1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
followi ng:
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 29
29 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 30
30 Substitute a known good ECM and recheck.
Was the problem solved?
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. —Go to Step 31Go to Step 32
31 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.—Veri fy repai r— Step Action Value(s) Yes No

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–383
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
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 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 6
6 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 7
7 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 8

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–385
19 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 20
20 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 21
21 Substitute a known good CKP sensor and recheck.
Was the problem solved?—Go to Step 22Go to Step 23
22 Replace the CKP sensor.
Is the action complete?—Veri fy repai r—
23 1. Using the Tech 2 and ignition “On” and engine
“Run”.
2. Monitor the following parameters in the data
display.
“Desired Injection Quantity” & “Injection Quantity”
“Desired Injection Start” & “Actual Injection Start”
Are the large gap or unstable parameter displayed
between “Desired” and “Actual”?
—Go to Step 27Go to Step 24 Step Action Value(s) Yes No
When idling or part-throttle When accelerated


HighDesired
Low
Ti m e Actu al
High
LowDesi red
Actu al
Ti m e

6E–386 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
24 Using the Tech 2 or the vacuum pump and check the
EGR valve operation for the following condition
through the small window.
ÅERestrict shaft movement. Check for objects sticking
the shaft, broken diaphragm or ex cessive carbon
deposit.
Tech 2:
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"EGR Solenoid Test" in the "Solenoid".
3. Operate the Tech 2 in accordance with procedure.
Solenoid 95%: EGR Valve Open
Solenoid 5%: EGR Valve Close
Vacuum Pump:
1. Using the vacuum pump. Disconnect the original
vacuum hose and connect the hose to the EGR
valve.
2. Apply vacuum pressure.
Vacuum Apply: EGR Valve Open
Vacuum Release: EGR Valve Close
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 25
25 Check the ex haust system for a possible restriction.
Damaged or collapsed pipes or catalytic converter.
Internal muffler failure.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 26
26 Visually/physically inspect for the following conditions.
Restrict fuel supply system. Check for a pinched
fuel hose/pipe.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 27
27 Replace the fuel filter.
Was the problem solved?—Verify repair Go to Step 28 Step Action Value(s) Yes No

Vacuum Pump Small Window