Isuzu KB P190. Manual - part 607

6E–258

ENGINE DRIVEABILITY AND EMISSIONS

EXCESSIVE EXHAUST EMISSIONS OR ODORS SYMPTOM

DEFINITIONS: Vehicle fails an emission test. There is excessive “rotten egg” smell. (Excessive odors do not
necessarily indicate excessive emissions.)

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.

Does the customer continual accelerate On/Off during
cold condition?

—

System OK

Go to Step 5

Is the customer using the incorrect fuel type?

—

Replace with

unleaded fuel

Go to Step 6

Check for vacuum leaks (vacuum lines, intake
manifold, throttle body, etc.)
Were any vacuum leaks found?

—

Go to Step 17

Go to Step 7

1. Check fuel cap for proper installation.

2. Secure the fuel cap if necessary.

Was a problem found?

—

Go to Step 17

Go to Step 8

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

—

Go to Step 17

Go to Step 9

1. Check for faulty, plugged or incorrectly installed

PCV valve.

2. Verify that the PCV system is not plugged.

Was a problem found?

—

Go to Step 17

Go to Step 10

Check the injector connectors, if any of the injectors
are connected to an incorrect cylinder, correct as
necessary.
Was a problem found?

—

Go to Step 17

Go to Step 11

Perform the “Injector Coil/Balance Test

”

(Refer to 6E-

98 page).
Was a problem found.

—

Go to Step 17

Go to Step 12

Check for a problem with the engine cooling system.
Was a problem found?

—

Go to Step 17

Go to Step 13

Check EVAP canister for fuel loading. Refer to
Evaporative Emission Control System.
Was a problem found?

—

Go to Step 17

Go to Step 14

Check the EVAP purge solenoid valve operation.
Is the valve operated normally?

—

Go to Step 17

Verify repair &

Go to Step 15

Check the exhaust system for a possible restriction:

• Damaged or collapsed pipes

• Internal catalytic converter failure
Was a problem found?

—

Verify repair &

Go to Step 16

Go to Step 17

ENGINE DRIVEABILITY AND EMISSIONS

6E–259

1. Remove excessive carbon buildup with a top

engine cleaner. Refer to the instructions on the top
engine cleaner can.

2. Perform the exhaust emission test.

Does the vehicle pass the test?

—

System OK

Go to Step 18

Perform the exhaust emission test.
Does the vehicle pass the test?

—

System OK

Go to Step 18

Run Engine.
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 19

Monitor “B1S1 (Bank 1 Sensor 1) Status” on the Tech
2.
Is the “B1S1 (Bank 1 Sensor 1) Status” in the rich
condition?

—

Go to Step 20

Go to Step 21

1. Check items that can cause the engine to run rich.

Refer to Diagnostic Aids in DTC P1167 “Fuel
Supply System Rich During Deceleration Fuel Cut
Off”. Make any necessary repairs.

2. Perform the exhaust emission test.

Does the vehicle pass the test?

—

System OK

Go to Step 22

1. Check items that can cause the engine to run

lean. Refer to Diagnostic Aids in DTC P1171 “Fuel
Supply System Lean During Power Enrichment”.
Make any necessary repairs.

2. Perform the exhaust emission test.

Does the vehicle pass the test?

—

System OK

Go to Step 22

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
Was a problem found?

—

Verify repair

Go to Step 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

Step

Action

Value(s)

Yes

6E–260

ENGINE DRIVEABILITY AND EMISSIONS

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 25

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

ENGINE DRIVEABILITY AND EMISSIONS

6E–261

DIESELING, RUN-ON SYMPTOM

DEFINITIONS: Engine continues to run after key is turned OFF, but runs very rough. If engine runs smoothly, check
the ignition switch and adjustment.

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 a short between battery voltage and the
ignition feed circuit.
Was a problem found?

—

Verify repair

Go to Step 5

Check the fuel leaking from injector. Refer to Fuel
System Diagnostic.
Was the problem found?

—

Verify repair

Go to Step 6

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 7

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 8

—

Verify repair

—

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