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Isuzu KB P190. Manual - part 605

6E–250

ENGINE DRIVEABILITY AND EMISSIONS

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 20

1. Check for faulty engine mounts.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to Step 21

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 22

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 23

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–251

LACK OF POWER, SLUGGISH OR SPONGY SYMPTOM

DEFINITIONS: Engine delivers less than expected power. Attempting part-throttle acceleration results in little or no
increase in vehicle speed.

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.

1. Remove and check the air filter element for dirt or

restrictions.

2. Replace the air filter element if necessary.

Was a repair required?

—

Verify repair

Go to Step 5

Check the ECM grounds to verify that they are clean
and tight. Refer to the ECM wiring diagrams.
Was a problem found?

—

Verify repair

Go to Step 6

1. Using a Tech 2, display the MAP sensor value in

comparison with atmosphere temperature.

2. Check for a faulty, plugged, or incorrectly installed

MAP sensor.

Was the problem found?

—

Verify repair

Go to Step 7

1. Using a Tech 2, display the ECT sensor and IAT

sensor value and warm up condition compared
with the typical data.

2. Check the specified value or wire.

Was the problem found?

—

Verify repair

Go to Step 8

Observe the throttle position display on the Tech 2
while slowly increasing throttle pedal.
Does the throttle position increase steady with
increasing smoothly?

—

Go to Step 9

Refer to

Diagnostic

Trouble Code

P0123 for

further

diagnosis

Check the knock sensor wire, shield wire, or
installation condition.
Was a problem found?

—

Verify repair

Go to Step 10

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 11

Check the fuel pressure. Refer to “Fuel System
Diagnosis

”

6E-108.

Was a problem found?

—

Verify repair

Go to Step 12

6E–252

ENGINE DRIVEABILITY AND EMISSIONS

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

—

Verify repair

Go to Step 13

Check items that can cause the engine to run rich.
Refer to DTC P1167 “Fuel Supply System Rich During
Deceleration Fuel Cut Off”.
Was a problem found?

—

Verify repair

Go to Step 14

Check items that can cause the engine to run lean.
Refer to DTC P1171 “Fuel Supply System Lean
During Power Enrichment”.
Was a problem found?

—

Verify repair

Go to Step 15

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

—

Verify repair

Go to Step 16

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 17

Drain sample fuel, visual inspection.
Any suspecion about the fuel, such as discoloration,
particle, contamination, water, unusual smell, then
drain the fuel from fuel tank.
Replace the fuel from know vehicle source.
If any suspencion of alcohol contamination,
completely drain the fuel, replace by fuel from known
vehicle source.

—

Verify repair

Go to Step 18

Check the exhaust system for a possible restriction:

• Damaged or collapsed pipes

• Internal muffler failure
Was a problem found?

—

Verify repair

Go to Step 19

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

• Low compression

• Leaking cylinder head gaskets

• Worn camshaft

• Loose timing belt
Was a problem found?

—

Verify repair

Go to Step 20

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 21

Step

Action

Value(s)

Yes

ENGINE DRIVEABILITY AND EMISSIONS

6E–253

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 22

—

Verify Repair

—

Step

Action

Value(s)

Yes

Content .. 603 604 605 606 ..