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Isuzu KB P190. Manual - part 608

6E–262

ENGINE DRIVEABILITY AND EMISSIONS

BACKFIRE SYMPTOM

DEFINITIONS: Fuel ignites in the intake manifold, or in the exhaust system, making a loud popping noise.

Step

Action

Value(s)

Yes

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to Step 2

Go to OBD

System Check

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

Was a visual/physical check performed?

—

Go to Step 4

Go to Visual /

physical Check.

Check for proper ignition voltage output with the spark
tester.
Was a problem found?

—

Verify repair

Go to Step 5

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 6

Visually/physically inspect all spark plug high-tension
cables. Check for the following conditions:

• Verify that the resistance of all spark plug high-

tension cables are less than the specified value.

• Verify that the all spark plug high-tension cables are

correctly fitted to eliminate cross-fitting.

• Verify that the all spark plug high-tension cables are

not arcing to ground.
Spraying the spark plug high-tension cables with a
light mist of water may help locate an intermittent
problem.

Was a problem found?

#1 cyl. 4.4k

Ω

#2 cyl. 3.6k

Ω

#3 cyl. 3.1k

Ω

#4 cyl. 2.8k

Ω

Verify repair

Go to Step 7

Check the fuel pressure. Refer to 6E-108 page “Fuel
System Diagnosis” .
Was a problem found?

—

Verify repair

Go to Step 8

Check for an intermittent ignition system malfunction:

• Intermittent CKP 58X signal

• Intermittent ignition feed circuit or sensor ground

circuit to the crankshaft position sensor.

Was a problem found?

—

Verify repair

Go to Step 9

Refer to 6E-108 page “Fuel System Diagnosis ”

determine if there is a problem with fuel delivery.
Was a problem found?

—

Verify repair

Go to Step 10

ENGINE DRIVEABILITY AND EMISSIONS

6E–263

Check for the following engine mechanical problems
(refer to Engine Mechanical):

• 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 11

Check leakage at exhaust system.
Check the intake and exhaust manifold for casting
flash. Refer to Engine Mechanical.
Was a problem found?

—

Verify repair

Go to Step 12

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 13

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 14

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

—

Step

Action

Value(s)

Yes

6E–264

ENGINE DRIVEABILITY AND EMISSIONS

ON-VEHICLE SERVICE PROCEDURE

ENGINE CONTROL MODULE (ECM)

Location
On the intake manifold.

Removal Procedure

1. Disconnect the negative battery cable.

2. Disconnect the two connectors from the ECM.

3. Remove four bolts.

4. Remove the ECM from bracket.

Installation Procedure

1. Put on the ECM to the bracket.

2. Tighten the ECM by four bolts with specified

tightening torque.

Tightening torque

• Bolts: 8.0 - 12.0 N·m (0.8 - 1.2 kgf·m)

3. Connect the two connectors to the ECM.

4. Connect the negative battery cable.

NOTE: Verify any DTCs (diagnosis Trouble Code) are
not stored after replacement.

CRANKSHAFT POSITION (CKP) SENSOR

Location
Left-hand side of the cylinder block. (Back of the A/C
compressor)

Removal Procedure

1. Disconnect the negative battery cable.

2. Remove the drive belt. Refer to Engine Mechanical

Section.

3. Remove the A/C compressor from engine. Refer to

Engine Mechanical Section.

4. Disconnect connector from the CKP sensor.

5. Loosen a bolt and remove the CKP sensor from the

cylinder block.

NOTE: Use caution to avoid any hot oil that might drip
out.

Installation Procedure

1. Install the CKP sensor to the cylinder block.

2. Tighten CKP sensor by a bolt with specified

tightening torque.

Tightening Torque

• Bolt: 6N·m (0.6kgf·m)

3. Reinstall the A/C compressor to the engine.

4. Reinstall the accessory drive belt.

5. Connect the negative battery cable.

NOTE: Verify any DTCs (diagnosis Trouble Code) are
not stored after replacement.

ENGINE DRIVEABILITY AND EMISSIONS

6E–265

ENGINE COOLANT TEMPERATURE (ECT)
SENSOR

Location
Installed to the thermostat housing.

Removal Procedure

1. Disconnect the negative battery cable.

2. Drain enough engine coolant so that the coolant

level will be below the ECT sensor.

3. Disconnect connector from the ECT sensor.

4. Loosen and remove the ECT sensor from the

thermostat housing.

NOTE: Cool down the engine before above procedures
are carried out.

Installation Procedure

1. Apply sealer to threads of screw at the ECT sensor.

2. Tighten the ECT sensor with specified tightening

torque.

Tightening Torque

• Bolt: 13N·m (1.3kgf·m)

3. Connect a ECT sensor connector to the ECT

sensor.

4. Fill the engine coolant.

5. Connect the negative battery cable.

NOTE: Verify any DTCs (diagnosis Trouble Code) are
not stored after replacement.
Verify no engine coolant leaking from the sensor
threads after replacement.

INTAKE AIR TEMPERATURE (IAT) SENSOR

Location
Installed to the intake duct housing.

Removal Procedure

1. Disconnect the negative battery cable.

2. Disconnect a IAT sensor connector from the IAT

sensor.

3. Remove the IAT sensor from the intake duct.

Installation Procedure

1. Install the IAT sensor into intake air duct.

2. Connect a IAT sensor connector to the IAT sensor.

3. Connect the negative battery cable.

NOTE: Verify any DTCs (diagnosis Trouble Code) are
not stored after replacement.

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