Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 249

ENGINE DRIVEABILITY AND EMISSIONS

6E–237

HESITATION, SAG, STUMBLE SYMPTOM

DEFINITIONS: 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.

Step

Action

Value(s)

Yes

No

1

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

—

Go to Step 2

Go to OBD 

System Check

2

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

3

Was a visual/physical check performed?

—

Go to Step 4

Go to Visual / 

physical Check.

4

Check the fuel quality.
Is the customer using improper fuel or degraded fuel?

—

Replace fuel

Go to Step 5

5

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 6

6

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 7

Refer to 

Diagnostic 

Trouble Code 

P0123 for 

further 

diagnosis

7

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

—

Verify repair

Go to Step 8

8

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 9

9

Check the fuel pressure. Refer to Fuel System
Diagnosis.
Was a problem found?

—

Verify repair

Go to Step 10

6E–238

ENGINE DRIVEABILITY AND EMISSIONS

10

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 11

Go to Step 12

11

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 12

12

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 13

13

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

—

Verify repair

Go to Step 14

14

Check for a loose ignition control module ground.
Was a problem found?

—

Verify repair

Go to Step 15

15

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 16

16

1. Check the ignition coil secondary resistance.

2. Replace the coil if it is greater than the specified

resistance.

Did the coil require replacement?

2.5k

Ω

Verify repair

Go to Step 17

17

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 18

18

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 19

19

Visually/physically check the vacuum hose for splits,
kinks and proper connections and routing.
Was a problem found?

—

Verify repair

Go to Step 20

Step

Action

Value(s)

Yes

No

ENGINE DRIVEABILITY AND EMISSIONS

6E–239

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

21

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

22

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 immobiliser system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobiliser System-ECM replacement” for
the ECM/Immobiliser linking procedure.

—

Verify Repair

—

Step

Action

Value(s)

Yes

No

6E–240

ENGINE DRIVEABILITY AND EMISSIONS

CUTS OUT, MISSES SYMPTOM

DEFINITIONS: Steady pulsation or jerking that follows
engine speed; usually more pronounced as engine load
increases.

Step

Action

Value(s)

Yes

No

1

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

—

Go to Step 2

Go to OBD 

System Check

2

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

3

Was a visual/physical check performed?

—

Go to Step 4

Go to Visual / 

physical Check.

4

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

—

Verify repair

Go to Step 5

5

Check for a loose or short circuit of ignition coil
module voltage feed.
Was a problem found?

—

Verify repair

Go to Step 6

6

Check for a loose or short circuit of ignition coil
module ground.
Was a problem found?

—

Verify repair

Go to Step 7

7

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

8

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

—

Verify repair

Go to Step 9

9

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 10

Go to Step 11