sensor ISUZU TROOPER 1998 Service Repair Manual

6E±266
ENGINE DRIVEABILITY AND EMISSIONS
Surges and/or Chuggles Symptom

 
StepNo Ye s Value(s) Action
101. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electric Ignition
System
for procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 11
111. Check for a loose ignition coil ground.
Refer to
Electric Ignition System.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 12
121. Check the ignition coils for cracks or carbon
tracking.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 13
131. Remove the spark plugs and check for wet plugs,
cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to
Electronic Ignition
System
.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 14
141. Check the injector connections.
2. If any of the injector connectors are connected to an
incorrect cylinder, correct as necessary.
Was a problem found?
ÐVerify repairGo to Step 15
151. Check PCM grounds for the cleanliness, tightness
and proper locations. Refer to the PCM wiring
diagrams in
Electrical Diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 16
161. Check MAF sensor connections.
2. If a problem is found, replace the faulty terminals as
necessary. Refer to
Electrical Diagnosis for wiring
repair procedures.
Was a problem found?
ÐVerify repairGo to Step 17
171. Visually/physically check vacuum hoses for splits,
kinks, and proper connections and routing as
shown on the ªVehicle Emission Control
Informationº label.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 18

6E±268
ENGINE DRIVEABILITY AND EMISSIONS
Lack of Power, Sluggish or Spongy Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Engine delivers less than expected power. Little or no
increase in speed when accelerator pedal is pushed
down part-way.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. 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?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to
Visual/Physic
al Check
41. Remove and check the air filter element for dirt or
restrictions. Refer to
Air Intake System in
ON-Vehicle Service.
2. Replace the air filter element if necessary.
Was a repair required?
ÐVerify repairGo to Step 5
51. Check for low fuel pressure. Refer to Fuel System
Pressure Test
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
61. Check for water- or alcohol-contaminated fuel.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Using Tech 2, monitor the knock sensor (KS)
system for excessive spark retard activity. Refer to
Knock Sensor (KS) System.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electronic Ignition
System
for procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
91. Remove the spark plugs and check for wet plugs,
cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to
Electronic Ignition
System
.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 10
101. Check the ignition coils for cracks or carbon
tracking.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 11

6E±276
ENGINE DRIVEABILITY AND EMISSIONS
Poor Fuel Economy Symptom

 
StepNo Ye s Value(s) Action
101. Check for an incorrect or faulty engine thermostat.
Refer to
Engine Cooling.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 11
111. Check for low engine compression. Refer to Engine
Mechanical
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 12
121. Check the TCC operation. Refer to 4L30-E
Transmission Diagnosis
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 13
131. Check the exhaust system for possible restriction:

Inspect the exhaust system for damaged or
collapsed pipes.

Inspect the muffler for heat distress or possible
internal failure.

Check for a possible plugged three-way
catalytic converter by checking the exhaust
system back pressure. Refer to
Restricted
Exhaust System Check
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 14
14Check for proper calibration of the speedometer.
Does the speed indicated on the speedometer closely
match the vehicle speed displayed on Tech 2?
ÐGo to Step 16Go to Step 15
15Diagnose and repair an inaccurate speedometer
condition as necessary. Refer to
Vehicle Speed
Sensor
in Electrical Diagnosis.
Was a problem found?
ÐVerify repairÐ
161. Check the air intake system and the crankcase for
air leaks. Refer to
Air Intake System and
Crankcase Ventilation System.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 17
171. Review all diagnostic procedures within this table.
2. When all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records buffer

All connections within a suspected circuit
and/or system.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 18
18Perform the procedure in Fuel System Pressure Test.
Was the fuel pressure normal?
Ð
Contact
Technical
Assistance
Verify repair

6E±280
ENGINE DRIVEABILITY AND EMISSIONS
Backfire Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Fuel ignites in the intake manifold, or in the exhaust
system, making a loud popping noise.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. 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?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to
Visual/Physic
al Check
41. Check for proper ignition voltage coil output with
spark tester 5-8840-0383-0. Refer to
Electric
Ignition System
for procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Remove spark plugs and check for wet plugs,
cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to
Electronic Ignition
System
.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs. Refer to
DTC P0172 to determine the
cause of a rich condition or
Engine Mechanical for an oil
fouling condition.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
61. Visually/physically inspect the ignition coils for
cracks.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Check for an intermittent ignition system
malfunction:

Intermittent CKP 58X signal.

Intermittent ignition feed circuit or sensor
ground circuit to the crankshaft position
sensor.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Check the fuel pressure. Refer to Fuel System
Pressure Test
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9

6E±285 ENGINE DRIVEABILITY AND EMISSIONS
Hesitation, Sag, Stumble Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
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.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. 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?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to
Visual/Physic
al Check
41. Check the fuel control heated oxygen sensors
(HO2S, B1S1 and B2S1). The fuel control heated
oxygen sensors (HO2S) should respond quickly to
different throttle positions. If they don't, check them
for silicon or other contaminants from fuel or use of
improper RTV sealant. The sensors may have a
white powdery coating.
Silicon contamination causes a high but false
HO2S signal voltage (rich exhaust indication).
The PCM will then reduce the amount of fuel
delivered to the engine, causing a severe
driveability problem. For more information, refer
to
Powertrain Control Module (PCM) and Sensors.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Check the fuel pressure. Refer to Fuel System
Pressure Test.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
6Observe the TP angle display on Tech 2 while slowly
increasing throttle pedal.
Does the TP angle display steadily increase from 0% at
closed throttle to 100% at WOT?
ÐGo to Step 7Go to Step 18
7Monitor the long term fuel trim on Tech 2.
Is the long term fuel trim significantly in the negative
range (rich condition)?
ÐGo to Step 8Go to Step 9
81. Check items that can cause the engine to run rich.
Refer to
Diagnostic Aids in DTC P0172 Diagnostic
Support
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 10
91. Check items that can cause the engine to run lean.
Refer to
Diagnostic Aids in DTC P0171 Diagnostic
Support
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 10

6E±286
ENGINE DRIVEABILITY AND EMISSIONS
Hesitation, Sag, Stumble Symptom

 
StepNo Ye s Value(s) Action
101. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electronic Ignition
System
for the procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 11
111. Check for a loose ignition coil ground.
Refer to
Electronic Ignition System.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 12
121. Check the ignition coils for cracks or carbon
tracking.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 13
131. Remove spark plugs and check for wet plugs,
cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to
Electronic Ignition
System
.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 14
141. Check the PCM grounds for clearness, tightness
and proper routing. Refer to the PCM wiring
diagrams in Electrical Diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 15
151. Check the MAF sensor connections.
2. If a problem is found, replace the faulty terminals as
necessary. Refer to
Electrical Diagnosis for wiring
repair procedures.
Was a problem found?
ÐVerify repairGo to Step 16
161. Visually/physically check vacuum hoses for splits,
kinks, and proper connections and routing as
shown on the ªVehicle Emission Control
Informationº label.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 17

6E±287 ENGINE DRIVEABILITY AND EMISSIONS
Hesitation, Sag, Stumble Symptom

 
StepNo Ye s Value(s) Action
171. 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

Freeze Frame data/Failure Records butter

All electrical connections within a suspected
circuit and/or system
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Contact
Technical
Assistance
18Replace the TP sensor.
Is the action complete?
ÐVerify repairÐ

6E±288
ENGINE DRIVEABILITY AND EMISSIONS
Default Matrix Table
Service Procedure Default Strategy
A referral strategy has been established to assist the
technician with additional information when the cause of
the failure cannot be determined. If no problem is found
after performing diagnostics, then refer to the default
matrix table for further diagnostic information.
Default Matrix Table
Strategy Based Diagnostic Charts
Initial DiagnosisDefault Section(s)
On-Board Diagnostic (OBD) System
CheckVehicle does not enter diagnostics.Chassis Electrical
On-Board Diagnostic (OBD) System
CheckVehicle enters diagnostics and
communicates with Tech 2. MIL is
ªONº in diagnostics. Engine does not
start and run.Ignition System Check
On-Board Diagnostic (OBD) System
CheckEngine starts and runs, no PCM
codes set. Customer complains of
vibration.Ð
On-Board Diagnostic (OBD) System
CheckEngine starts and runs, no PCM
codes set. Customer complains of
harsh or soft shift, poor performance,
delayed or no engagement into drive
or reverse, transmission fluid leak,
transmission noise or vibration, or
improper TCC operation.Automatic Transmission
PCM Power and Ground CheckOn-Board Diagnostic (OBD) System
Check.Chassis Electrical
PCM Power and Ground CheckOn-Board Diagnostic (OBD) System
Check. PCM power and ground
circuits OK. Data link voltage
incorrect.Chassis Electrical
On-Board Diagnostic (OBD) System
CheckEngine starts and runs, no PCM
codes set. Customer complains of
harsh or soft shift, poor performance,
delayed or no engagement into drive
or reverse, transmission fluid leak,
transmission noise or vibration, or
improper TCC operation.Automatic Transmission
SymptomsInitial DiagnosisDefault Section(s)
Intermittents1. On-board Diagnostic (OBD)
system check.
2. Careful visual/physical
inspections.Chassis Electrical
Hard Starts1. OBD system check.
2. Sensors (ECT, MAP, MAF, TP) ;
MAP output chart.
3. Fuel system electrical test, fuel
system diagnosis.
4. Ignition system.
5. IAC system check.Engine Mechanical, Ignition
System Check, Exhaust System
Diagnosis
Surges and/or Chuggles1. OBD system check.
2. Heated oxygen sensors.
3. Fuel system diagnosis.
4. Ignition system.Calibration ID ªBroadcast
Codeº/Service Bulletins, Ignition
System Check, Generator
Output, Exhaust System
Diagnosis, 4L30-E System Test

6E±289 ENGINE DRIVEABILITY AND EMISSIONS
Symptoms Default Section(s)Initial Diagnosis
Lack of Power, Sluggish or Spongy1. OBD system check.
2. Fuel system diagnosis.
3. Ignition system.
4. Knock sensor.
5. EGR operation.
6. EGR system check.Refer to Exhaust System in
Engine Exhaust, TCC Operation,
Calibration ID/Service Bulletins
Detonation/Spark Knock1. OBD system check.
2. Transmission range switch.
3. EGR operation.
4. EGR system check.
5. TCC operation.
6. Fuel system diagnosis.
7. Ignition system.
8. Knock sensor.TCC operation, Cooling System,
Ignition System Check,
Calibration ID/Service Bulletins
Hesitation, Sag, Stumble1. OBD system check.
2. TP.
3. MAP output check.
4. Fuel system diagnosis.
5. Fuel injector and fuel injector
balance test.
6. Ignition system.EGR Operation, EGR System
Check, Generator Output
Voltage (refer to
Chassis
Electrical
), Calibration ID/Service
Bulletins, Ignition System Check
Cuts Out, Misses1. OBD system check.
2. Cylinder balance test.Ignition System Check
Rough, Unstable, or Incorrect Idle,
Stalling1. OBD system check.
2. Fuel injector and fuel injector
balance test.
3. Ignition system.
4. IAC operation.
5. EGR operation.MAP Output Check, Throttle
Linkage, IAC System Check,
EGR System Check, A/C Clutch
Control Circuit Diagnosis,
Crankcase Ventilation System,
Calibration ID/Service Bulletins,
Generator Output Voltage (refer
to
Chassis Electrical), Exhaust
Diagnosis
Poor Fuel Economy1. OBD system check.
2. Careful visual/physical inspection.
3. Ignition system.
4. Cooling system.TCC Operation, Exhaust System
(refer to
Engine Exhaust)
Engine Cranks But Will Not Run1. OBD system check.Fuel System Electrical
Diagnosis, Fuel System
Diagnosis, Fuel Injector and Fuel
Injector Balance Test.
Excessive Exhaust Emissions or
Odors1. OBD system check.
2. Emission test.
3. Cooling system.
4. Fuel system diagnosis.
5. Fuel injector and fuel injector
balance test.
6. Crankcase ventilation system.
7. Ignition system.
8. MAP output check.EGR System Check, Exhaust
Diagnosis, Calibration ID/Service
Bulletins
Dieseling, Run-On1. OBD system check.
2. Careful visual/physical inspection.
3. Fuel system diagnosis.Ð

6E±290
ENGINE DRIVEABILITY AND EMISSIONS
Symptoms Default Section(s)Initial Diagnosis
Backfire1. OBD system check.
2. Ignition system.
3. Fuel system diagnosis.
4. Fuel injector and fuel injector
balance test.
5. EGR operation, EGR system
check.Exhaust System Diagnosis,
Intake Casting Flash, Ignition
System Check
Catalyst Monitor1. OBD system check.
2. Careful visual/physical inspection.
3. Heated oxygen sensors.Exhaust System
Fuel Trim1. OBD system check.
2. Careful visual/physical inspection.
3. Fuel system diagnosis.
4. Heated oxygen sensors, MAF
sensors.Exhaust System Intake Air
System
Evaporative Emissions1. OBD system check.
2. Careful visual/physical inspection.
3. Fuel system diagnosis.Ð
Heated Oxygen Sensors1. OBD system check.
2. Careful visual/physical inspection.Exhaust System