Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 184

6E–340

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

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

—

Replace the injection pump assembly.
Is the action complete?

—

Verify repair

—

Step

Action

Value(s)

Yes

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

6E–341

POOR FUEL ECONOMY SYMPTOM

DEFINITIONS: Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, economy
is noticeably lower than it was on this vehicle at one time, as previously shown by an actual road test. (Larger than
standard tires will cause odometer readings to be incorrect, and that may cause fuel economy to appear poor when it
is actually normal.)

Step

Action

Value(s)

Yes

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

—

Go to Step 2

Go to On Board

Diagnostic

(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 visually/physical check performed?

—

Go to Step 4

Go to Visual /

physical Check.

Check owner's driving habits.

• Is the A/C “On” full time?

• Are tires at the correct pressure?

• Are excessively heavy loads being carried?

• Is acceleration too much, too often?

—

Go to Step 5

Go to Step 6

Review the items in Step 4 with the customer and
advise as necessary.
Is the action complete?

—

System OK

—

Check for low engine coolant level.
Was a problem found?

—

Verify repair

Go to Step 7

Check for incorrect or faulty engine thermostat. Refer
to Engine Cooling.
Was a problem found?

—

Verify repair

Go to Step 8

Check for proper calibration of the speedometer.
Does the speed indicated on the speed meter closely
match the vehicle speed displayed on the Tech 2?

—

Go to Step 10

Go to Step 9

Diagnose and repair the inaccurate speedometer
condition as necessary. Refer to Vehicle Speed
Sensor in Electrical Diagnosis.

—

Verify repair

—

Check for proper calibration of the fuel gauge.
Was a problem found?

—

Verify repair

Go to Step 11

Check the torque converter clutch (TCC) for proper
operation (if A/T model). If a problem is found, repair
as necessary.
Was a problem found?

—

Verify repair

Go to Step 12

1. Using the Tech 2, ignition “On” and engine “Off”.

2. Monitor the “Neutral Switch” in the data display.

Does the Tech 2 indicate correct “Neutral Switch”
status depending on any shift positions?
If a problem is found, repair as necessary.
Was the problem found?

—

Verify repair

Go to Step 13

6E–342

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

1. Using the Tech 2, ignition “On” and engine “Run”.

2. Monitor the “A/C Information Switch” in the data

display.

Does the Tech 2 indicate correct “A/C Information
Switch” status depending on A/C switch position?
If a problem is found, repair as necessary.
Was the problem found?

—

Verify repair

Go to Step 14

Visually/physically inspect for the following conditions.

• Restrict air intake system. Check for a restricted air

filter element, or foreign objects blocking the air
intake system

• Check for objects blocking or excessive deposits in

the throttle bore and on the throttle plate

• Check for a condition that causes a large vacuum

leak, such as an incorrectly installed or faulty
crankcase ventilation hose.

• Restrict air intake system at the turbocharger.
Check for objects blocking the turbocharger
compressor wheel or turbine shaft sticking.
If a problem is found, repair as necessary.
Was a problem found?

—

Verify repair

Go to Step 15

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

sensor value.

2. Check the displayed value.

Does the Tech 2 indicate correct temperature
depending on engine condition?
If a problem is found, repair as necessary.
Was the problem found?

—

Verify repair

Go to Step 16

1. Using the Tech 2, display the FT sensor value.

2. Check the displayed value.

Does the Tech 2 indicate correct temperature
depending on engine condition?
If a problem is found, repair as necessary.
Was the problem found?

—

Go to Step 31

Go to Step 17

1. Using the Tech 2, ignition “On” and engine “Run”.

2. Monitor the “Mass Air Flow” in the data display.

Does the Tech 2 indicate correct “Mass Air Flow”
depending on accelerator pedal operation?

—

Go to Step 22

Go to Step 18

Remove the MAF & IAT sensor assembly and check
for the following conditions.

• Objects blocking at the MAF sensor element.
If a problem is found, repair as necessary.
Was the problem found?

—

Verify repair

Go to Step 19

Check the MAF sensor harness for the following
conditions.

• Check for poor connector connection.

• Check for misrouted harness.

• Check for any accessory parts which may cause

electric interference.

If a problem is found, repair as necessary.
Was a problem found?

—

Verify repair

Go to Step 20

Step

Action

Value(s)

Yes

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

6E–343

Substitute a known good MAF & IAT sensor assembly
and recheck.
Was the problem solved?

—

Go to Step 21

Go to Step 31

Replace the MAF & IAT sensor assembly.
Is the action complete?

—

Verify repair

—

1. Using the Tech 2, ignition “On” and engine “Off”.

2. Monitor the “Pedal/Throttle Position” and “Idle

Switch” in the data display.

Does the Tech 2 indicate correct “Pedal/Throttle
Position” from 0% to 100% and correct “Idle Switch”
status depending on accelerator pedal operation?

—

Go to Step 27

Go to Step 23

1. Using the Tech 2, ignition “On” and engine “Off”.

2. Monitor the “Pedal/Throttle Position” and “Idle

Switch” in the data display.

3. Adjust the accelerator cable or TPS within 0% to

100%.

Was the problem solved?

—

Verify repair

Go to Step 24

Check the TPS harness for the following conditions.

• Check for poor connector connection.

• Check for misrouted harness.

• Check for any accessory parts which may cause

electric interference.

If a problem is found, repair as necessary.
Was a problem found?

—

Verify repair

Go to Step 25

Substitute a known good TPS and recheck.
Was the problem solved?

—

Go to Step 26

Go to Step 31

Replace the TPS.
Is the action complete?

—

Verify repair

—

Remove the injection nozzles from the engine and
check for the following conditions.

• Improper splay condition.

• Operating pressure is incorrect.
If a problem is found, repair as necessary.
Was the problem found?

—

Replace the

injection nozzle

and verify repair

Go to Step 28

Step

Action

Value(s)

Yes

Stage

20.0 - 21.0 Mpa

(204 - 214 kg/cm

)

34.3 - 35.8 Mpa

(350 - 365 kg/cm

)

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