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Isuzu KB P190. Manual - part 595

6E–210

ENGINE DRIVEABILITY AND EMISSIONS

Using the DVM and check the “Check Engine” lamp
circuit.
Breaker box is available:

1. Ignition “Off”, engine “Off”.

2. Install the breaker box as type A. (ECM

disconnected) Refer to 6E-88 page.

3. Remove the meter connector.

4. Check the circuit for open or short to ground

circuit.

Was the problem found?

Breaker box is not available:

1. Ignition “Off”, engine “Off”.

2. Disconnect the ECM connector.

3. Remove the meter connector.

4. Check the circuit for open or short to ground

circuit.

Was the problem found?

—

Repair faulty

harness and

verify repair

Go to Step 9

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 10

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

J2-25

Breaker Box

B-24

C-56(J2)

B-24

ENGINE DRIVEABILITY AND EMISSIONS

6E–211

DIAGNOSTIC TROUBLE CODE (DTC) P1167 FUEL SUPPLY SYSTEM RICH

DURING DECELERATION FUEL CUT OFF

Condition for setting the DTC and action taken when the DTC sets

Circuit Description

The engine control module (ECM) internal circuitry can
identify if the vehicle fuel system is capable of supplying
adequate amounts of fuel during deceleration (fuel cut
off). The ECM monitors the voltage of the oxygen
sensor during fuel cut off. When a fuel cut off mode of
operation is requested during “Closed Loop” operation
(by deceleration), the ECM will provide more fuel to the
engine. Under these conditions the ECM should detect
a “lean” condition (low oxygen sensor voltage). If this

“lean” exhaust is not detected at this time, a Diagnostic
Trouble Code P1167 will set.

Diagnostic Aids

Check the following items:

• Fuel pressure - The system will go rich if pressure is

too high. The ECM can compensate for some
increase. However, if fuel pressure is too high, a
Diagnostic Trouble Code P1167 may be set. Refer to
Fuel System Diagnosis.

Code

Type

DTC Name

DTC Setting Condition

Fail-Safe (Back Up)

P1167

Fuel Supply System Rich During
Deceleration Fuel Cutoff

1. No DTC relating to MAP sensor, TPS,

EVAP purge, ECT sensor, CKP sensor,
VSS, injector control circuit and ignition
control circuit.

2. O

sensor bank 1 output voltage is more

than 550mV in deceleration fuel cutoff
mode.

No fail-safe function.

6E–212

ENGINE DRIVEABILITY AND EMISSIONS

• Perform “Injector Balance Test” - Refer to Fuel

System Diagnosis.

• Check the EVAP canister for fuel saturation - If full of

fuel, check canister control and hoses. Refer to
Evaporative (EVAP) Emission Control System.

• Check for a leak in the fuel pressure regulator

diaphragm by checking the vacuum line to toe
regulator for the presence of fuel.

• An intermittent TP sensor output will cause the

system to go rich due to a false indication of the
engine accelerating.

• Silicon contamination of the HO2S can also cause a

high HO2S voltage to be indicated. This condition is
indicated by a powdery white deposit on the portion
of the HO2S exposed to the exhaust stream. If
contamination is noticed, replace the affected HO2S.

Diagnostic Trouble Code (DTC) P1167

Fuel Supply System Rich During Deceleration Fuel Cutoff

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. Connect the Tech 2.

2. Review and record the failure information.

3. Select “F0: Read DTC Infor By Priority” in “F0:

Diagnostic Trouble Code”.

Is the DTC P1167 stored as “Present Failure”?

—

Go to Step 3

Refer to

Diagnostic Aids

and Go to Step

1. Using the Tech2, ignition “On” and engine “Off”.

2. Select “Clear DTC Information” with the Tech2 and

clear the DTC information.

3. Operate the vehicle and monitor the “F5: Failed

This Ignition” in “F2: DTC Information”.

Was the DTC P1167 stored in this ignition cycle?

—

Go to Step 4

Refer to

Diagnostic Aids

and Go to Step

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

2. Monitor the “Throttle Position” in the data display.

Does the Tech 2 indicate correct “Throttle Position” in
accordance with accelerator pedal operation?

—

Go to Step 6

Go to Step 5

Check for the following conditions.

• Objects blocking the throttle valve.

• Incorrectly installed.
If a problem is found, repair as necessary.
Was the problem found?

—

Verify repair

Go to Step 12

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

2. Monitor the “Manifold Absolute Pressure” in the

data display.

Does the Tech 2 indicate correct “Manifold Absolute
Pressure” in accordance with engine speed or
acceleration?

—

Go to Step 8

Go to Step 7

Remove the MAP sensor and check for the following
conditions.

• Objects blocking the air cleaner.

• Objects blocking the MAP sensor.

• Objects blocking the throttle valve.

• Vacuum leaking at intake duct.

• Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?

—

Verify repair

Go to Step 13

ENGINE DRIVEABILITY AND EMISSIONS

6E–213

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

2. Select the “Miscellaneous Test” and perform the

“IAC Control” in the “IAC System”.

3. Operate the Tech 2 in accordance with procedure.

Was the engine speed changed, when the IAC valve
is operating step by step?

—

Go to Step 10

Go to Step 9

Check for the following conditions.

• Objects blocking the IAC valve.

• Objects blocking the throttle valve.

• Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?

—

Verify repair

Go to Step 14

Check for injector for the affected bank.
Refer to “Injector Coil Test & Injector Balance Test
Procedure” 6E-98 page.
Was the injector operation correct?

—

Go to Step 11

Refer to Injector

Coil Test &

Injector

Balance Test

Procedure

Check for fuel pressure.
Refer to “Fuel System Diagnosis” 6E-108 page.
Was the fuel pressure correct?

—

Go to Step 15

Refer to Fuel

System

Diagnosis

Replace the TPS.
Is the action complete?

—

Verify repair

—

Replace the MAP sensor.
Is the action complete?

—

Verify repair

—

Replace the IAC valve.
Is the action complete?

—

Verify repair

—

Replace the O

sensor.

Was the problem solved?

—

Verify repair

Go to Step 16

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 17

—

Verify repair

—

Step

Action

Value(s)

Yes

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