check engine ISUZU TROOPER 1998 Service Manual PDF

5C – 14 POWER ASSISTED BRAKE SYSTEM
CHECKING BRAKE PEDAL TRAVEL
1. Pedal height (L3) must be measured after starting
the engine and removing it several times to apply
vacuum to the vacuum booster fully.
NOTE:
Pedal height (L3) must be 100 mm (3.9 in)/85 mm (3.5
in) (LHD/RHD) or more when about 50 kg (110.25 lb)
of stepping force is applied.
2. If the measured value is lower than the above
range, air existing in the hydrauic system is
suspected and perform bleeding procedure.
FRONT AND REAR DISC BRAKE PADS
INSPECTION
Check the outer pad by looking at each caliper from
above. Check the thickness on the inner pad by
looking down through the inspection hole in the top of
the caliper. Whenever the pad is worn to about the
thickness of the pad base, the pad should be removed
for further measurements. The pad should be
replaced anytime the pad thickness (t) is worn to
within 1.0 mm (0.039 in) of the pad itself.
The disc pads have a wear indicator that makes a
noise when the pad wears to where replacement is
required.
Minimum Limit mm (in)
1.0 (0.039)
SERVICING THE FRONT BRAKE ROTOR
In the manufacturing of the front brake rotor, all the
tolerances regarding surface finish, parallelism and
lateral runout are held very closely. The maintenance
of these tolerances provide the surface necessary to
assure smooth brake operation.
LATERAL RUNOUT
Lateral runout is the movement of the rotor from side
to side as it rotates on the spindle. This could also be
referred to as “rotor wobble”.
This movement causes the piston to be knocked back
into its bore. This results in additional pedal travel and
a vibration during braking.
t

POWER ASSISTED BRAKE SYSTEM 5C – 23
VACUUM BOOSTER
This booster is a tandem vacuum unit with a diaphragm effective diameter 205 mm + 230 mm (gasoline
engine model) / 180 mm + 205 mm (diesel engine model). In normal operating mode, with the service
brakes in the released position, the tandem vacuum booster operates with vacuum on both sides of its
diaphragms. When the brakes are applied, air at atmospheric pressure is admitted to one side of each
diaphragm to provide the power assist. When the service brake is released, the atmospheric air is shut
off from the one side of each diaphragm. The air is then drawn from the booster through the vacuum
check valve to the vacuum source.
CAUTION:
1) If any hydraulic component is removed or disconnected, it may be necessary to bleed all or part of
the brake system.
2) The torque values specified are for dry, unlubricated fasteners.
3) The vacuum booster is not repairable and must be replaced as complete assembly.

5C – 42 POWER ASSISTED BRAKE SYSTEM
REMOVAL
•Before removing the vacuum booster assembly,
disconnect and remove brake pipes.
1. Master Cylinder
•Refer to Master Cylinder Assembly in this Section.
CAUTION:
When removing master cylinder from vacuum booster,
be sure to get rid of the internal negative pressure of
the vacuum booster (by, for instance, disconnecting
vacuum hose) in advance.
If any negative pressure remains in the vacuum
booster, the piston may possibly come out when the
master cylinder is being removed, letting the brake
fluid run out.
While removing master cylinder, further, do not hold
the piston as it can be easily pulled out.
Outside surface of the piston is the surface on which
seals are to slide. Care should be taken to keep the
surface free of cuts and dents.
2. Vacuum Hose
3. Yoke Clevis
•Disconnect the yoke clevis from the brake pedal.
4. Vacuum Booster Fixing Nut
5. Vacuum Booster
INSPECTION AND REPAIR
Vacuum Hose
Inspect the check valve (1), which is installed inside
the vacuum hose.
1) Air should pass freely from the vacuum booster
side (3) to the engine side (2).
2) Air should not pass from the engine side (2) to the
vacuum booster side (3). If it does, the check valve
is inoperative and vacuum hose must be replaced.
INSTALLATION
5. Vacuum Booster
Vacuum booster push rod adjustment.
NOTE:
When replacing either master cylinder or vacuum
booster, be sure to measure push rod, and adjust
required.
Push rod gauge: 5-8840-2300-0 (J-39216)
Vacuum pump: 5-8840-0279-0 (J-23738-A)
Push rod support: 5-8840-2305-0 (J-39241)
1) Remove retainer from vacuum booster front shell
using a small screwdriver. Then gently draw plate
and seal assembly out of the shell inside.
ENG
1
2 3
360RX001

6A±4
ENGINE MECHANICAL
Engine Diagnosis
Hard Starting
1. Starting Motor Does Not Turn Over
Troubleshooting Procedure
Turn on headlights and starter switch.
Condition
Possible causeCorrection
Headlights go out or dim
considerably
Battery run down or under chargedRecharge or replace battery
considerablyTerminals poorly connectedClean battery posts and terminals
and connect properly
Starting motor coil circuit shortedOverhaul or replace
Starting motor defectiveOverhaul or replace
2. Ignition Trouble Ð Starting Motor Turns Over But Engine Does Not Start
Spark Test
Disconnect an igniton coil from any spark plug. Connect
the spark plug tester 5±8840±0607±0, start the engine,
and check if a spark is generated in the spark plug tester.
Before starting the engine, make sure that the spark plugtester is properly grounded. To avoid electrical shock, do
not touch the part where insulation of the igniton coil is
broken while the engine is running.
Condition
Possible causeCorrection
Spark jumps across gapSpark plug defectiveClean, adjust spark gap or replace
Ignition timing incorrectRefer to Ignition System
Fuel not reaching fuel injector(s) or
engineRefer to item 3 (Trouble in fuel
system)
Valve timing incorrectAdjust
Engine lacks compressionRefer to item 4 (Engine lacks
compression)
No sparking takes placeIgnition coil disconnected or brokenConnect properly or replace
Electronic Ignition System with
moduleReplace
Poor connections in engine harnessCorrect
Powertrain Control Module cable
disconnected or defectiveCorrect or replace
3. Trouble In Fuel System
Condition
Possible causeCorrection
Starting motor turns over and spark
occurs but engine does not start
Fuel tank emptyFill
occurs but engine does not start.Water in fuel systemClean
Fuel filter cloggedReplace filter
Fuel pipe cloggedClean or replace
Fuel pump defectiveReplace
Fuel pump circuit openCorrect or replace
Evaporative Emission Control
System circuit cloggedCorrect or replace
Multiport Fuel Injection System faultyRefer to ªElectronic Fuel Injectionº
section

6A±5
ENGINE MECHANICAL
4. Engine Lacks Compression
Condition
Possible causeCorrection
Engine lacks compressionSpark plug loosely fitted or spark
plug gasket defectiveTighten to specified torque or replace
gasket
Valve timing incorrectAdjust
Cylinder head gasket defectiveReplace gasket
Valve incorrectly seatedLap valve
Valve stem seizedReplace valve and valve guide
Valve spring weakened or brokenReplace
Cylinder or piston rings wornOverhaul engine
Piston ring seizedOverhaul engine.
Engine Compression Test Procedure
1. Start and run the engine until the engine reaches
normal operating temperature.
2. Turn the engine off.
3. Remove all the spark plugs.
4. Remove ignition coil fuse (15A) and disable the
ignition system.
5. Remove the fuel pump relay from the relay and fuse
box.
6. Engage the starter and check that the cranking speed
is approximately 300 rpm.7. Install cylinder compression gauge into spark plug
hole.
8. With the throttle valve opened fully, keep the starter
engaged until the compression gage needle reaches
the maximum level. Note the reading.
9. Repeat the test with each cylinder.
If the compression pressure obtained falls below the
limit, engine overhaul is necessary.
Limit; 1000 kPa (145 psi)

6A±8
ENGINE MECHANICAL
Hesitation
ConditionPossible causeCorrection
Hesitation on accelerationThrottle Position Sensor adjustment
incorrectReplace throttle valve assembly
Throttle Position Sensor circuit open
or shortedCorrect or replace
Excessive play in accelerator linkageAdjust or replace
Mass Airflow Sensor circuit open or
poor connectionsCorrect or replace
Mass Airflow Sensor defectiveReplace
Manifold Absolute Pressure (MAP)
Sensor circuit open or shortedCorrect or replace
MAP Sensor defectiveReplace
Intake Air Temperature (IAT) Sensor
circuit open or shortedCorrect or replace
Knock Sensor (KS) Circuit open or
poor connectionsCorrect or replace
KS defectiveReplace
KS Module circuits open or shortedCorrect or replace
KS Module defectiveReplace
IAT Sensor defectiveReplace
Hesitation at high speedsFuel tank strainer cloggedClean or replace
(Fuel pressure too low)Fuel pipe cloggedClean or replace
Fuel filter cloggedReplace
Defective fuel pump systemCheck and replace
Fuel Pressure Control Valve leakingReplace
Hesitation at high speeds
(Fuel injector not working normally)Power supply or ground circuit for
Multiport Fuel Injection System
shorted or openCheck and correct or replace
Fuel Injector defectiveReplace
Cable of Multiport Fuel Injection
System circuit open or poor
connectionsCorrect or replace

6A±9
ENGINE MECHANICAL
Condition CorrectionPossible cause
Hesitation at high speedsPowertrain Control Module defectiveReplace
Throttle Position Sensor cable
broken or poor connectionsCorrect or replace
Throttle Position Sensor defectiveReplace
Engine Coolant Temperature Sensor
circuit open or shortedCorrect or replace
Engine Coolant Temperature Sensor
defectiveReplace
Mass Airflow Sensor circuit open or
poor connectionsCorrect or replace
Mass Airflow Sensor defectiveReplace
MAP Sensor cable broken or poor
connectionsCorrect or replace
MAP Sensor defectiveReplace
IAT Sensor circuit open or poor
connectionsCorrect or replace
IAT Sensor defectiveReplace
KS circuit open or poor connectionsCorrect or replace
KS defectiveReplace
KS Module circuit open or shortedCorrect or replace
KS Module defectiveReplace
Throttle valve not fully openedCheck and correct or replace
Air Cleaner Filter cloggedReplace filter element
Power supply voltage too lowCheck and correct or replace

6A±16
ENGINE MECHANICAL
Lubrication Problems
ConditionPossible causeCorrection
Oil pressure too lowWrong oil in useReplace with correct engine oil
Relief valve stickingReplace
Oil pump not operating properlyCorrect or replace
Oil pump strainer cloggedClean or replace strainer
Oil pump wornReplace
Oil pressure gauge defectiveCorrect or replace
Crankshaft bearing or connecting
rod bearing wornReplace
Oil contaminationWrong oil in useReplace with correct engine oil
Oil filter cloggedReplace oil filter
Cylinder head gasket damageReplace gasket
Burned gases leakingReplace piston and piston rings or
cylinder body assembly
Oil not reaching valve systemOil passage in cylinder head or
cylinder body cloggedClean or correct
Engine Oil Pressure Check
1. Check for dirt, gasoline or water in the engine oil.
a. Check the viscosity of the oil.
b. Change the oil if the viscosity is outside the
specified standard.
c. Refer to the ªMaintenance and Lubricationº section
of this manual.
2. Check the engine oil level.
The level should fall somewhere between the ªADDº
and the ªFULLº marks on the oil level dipstick.
If the oil level does not reach the ªADDº mark on the
oil level dipstick, engine oil must be added.3. Remove the oil pressure unit.
4. Install an oil pressure gauge.
5. Start the engine and allow the engine to reach normal
operating temperature (About 80
C).
6. Measure the oil pressure.
Oil pressure should be:
392±550 kPa (56.9±80.4 psi) at 3000 rpm.
7. Stop the engine.
8. Remove the oil pressure gauge.
9. Install the oil pressure unit.
10. Start the engine and check for leaks.

6A±17
ENGINE MECHANICAL
Malfunction Indicator Lamp
The instrument panel ªCHECK ENGINEº Malfunction
Indicator Lamp (MIL) illuminates by self diagnosticsystem when the system checks the starting of engine, or
senses malfunctions.
Condition
Possible causeCorrection
ªCHECK ENGINEº MIL does not
illuminate at the starting of engine
Bulb defectiveReplace
illuminate at the starting of engineMIL circuit openCorrect or replace
Command signal circuit to operate
self diagnostic system shortedCorrect or replace
Engine Control Module (PCM) cable
loosely connected, disconnected or
defectiveCorrect or replace
PCM defectiveReplace
ªCHECK ENGINEº MIL illuminates,
and stays onDeterioration of heated oxygen
sensor internal elementReplace
Heated oxygen sensor connector
terminal improper contactReconnect properly
Heated oxygen sensor lead wire
shortedCorrect
Heated oxygen sensor circuit openCorrect or replace
Deterioration of engine coolant
temperature sensor internal elementReplace
Engine coolant temperature sensor
connector terminal improper contactReconnect properly
Engine coolant temperature sensor
lead wire shortedCorrect
Engine coolant temperature sensor
circuit openCorrect or replace
Throttle position sensor open or
shorted circuitsCorrect or replace
Deterioration of crankshaft position
sensorReplace
Crankshaft position sensor circuit
open or shortedCorrect or replace
Vehicle speed sensor circuit openCorrect or replace
Manifold absolute pressure sensor
circuit open or shortedCorrect or replace
Intake air temperature sensor circuit
open or shortedCorrect or replace
Fuel injector circuit open or shortedCorrect or replace
PCM driver transistor defectiveReplace PCM
Malfunctioning of PCM RAM
(Random Access Memory) or ROM
(Read Only Memory)Replace PCM

6A±58
ENGINE MECHANICAL
1. Measure the valve stem diameter with a micrometer.
If the valve stem diameter is less than the specified
limit, the valve and the valve guide must be replaced
as a set.
Diameter of Valve Stem
Intake
Standard : 5.977 mm±5.959 mm
(0.2353 in±0.2346 in)
Limit : 5.90 mm (0.2323 in)
Exhaust
Standard : 5.952 mm±5.970 mm
(0.2343 in±0.2350 in)
Limit : 5.90 mm (0.2323 in)
014RS007
2. Measure the inside diameter of the valve guide with a
micrometer. Subtract the measured outer diameter of
the valve stem from the measured inner diameter of
the valve guide. If the value exceeds the specified
limit, the valve and the valve guide must be replaced
as a set.
Inside Diameter of the Vale Guide
Inlet clearance
Standard : 0.023 mm±0.056 mm
(0.0009 in±0.0002 in)
Limit : 0.20 mm (0.00787 in)
Exhaust clearance
Standard : 0.030 mm±0.063 mm
(0.0012 in±0.0025 in)
Limit : 0.20 mm (0.00787 in)
Valve Guide Replacement
1. Using Valve guide replacer: 5±8840±2442±0, drive
out the valve guide from the combustion chamber
side.
014RS008
2. Apply engine oil to the outside of the valve guide.
Using valve guide replacer 5±8840±2442±0, drive in
a new valve guide from the camshaft side, and check
the valve guide height.
Valve guide upper end height: 13.0 mm (0.5118
in)
(Measured from the cylinder head upper face)
014RW046
3. Check the clearance. If the clearance is less than the
specified value, ream the inside diameter of valve
guide. Using a sharp 6 mm reamer, ream the valve
guide to obtain the specified clearance.
Valve Seat
1. Measure the protrusion of the valve stem when a new
valve is installed in the cylinder head. If the protrusion
of the valve stem exceeds the limit, replace the valve
seat insert or the cylinder head assembly.
Protrusion of valve stem
Intake
Standard: 39.32 mm (1.5480 in)