Mitsubishi Montero (2004+). Manual - part 222

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-375

STEP 14. Check for entry of foreign matter (water,
kerosene, etc.) into fuel.
Q: Are there any abnormalities?

YES : Replace the fuel. Then go to Step 16.
NO : Go to Step 15.

STEP 15. Replace the right bank injector.
(1) Replace the right bank injector.
(2) Carry out a test drive with the drive cycle pattern. Refer to

Diagnostic Function

− OBD-II Drive Cycle − Procedure 2 −

Fuel Trim Monitor

P.13A-4

(3) Check in the diagnostic trouble code (DTC).
Q: Is DTC P0171 set?

YES : Replace the PCM. Then go to Step 16.
NO : The inspection is complete.

STEP 16. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

Diagnostic Function

− OBD-II Drive Cycle − Procedure 2 −

Fuel Trim Monitor

P.13A-4

(2) Check the diagnostic trouble code (DTC).
Q: Is the DTC P0171 output?

YES : Retry the troubleshooting.
NO : The inspection is complete.

DTC P0172: System too Rich (bank 1)

Fuel Trim Circuit

• Refer to DTC P0201 − P0206, Injector Circuit.

P.13A-421

CIRCUIT OPERATION

• Refer to DTC P0201 − P0206, Injector Circuit.

P.13A-421

TECHNICAL DESCRIPTION

• If a malfunction occurs in the fuel system, the fuel

trim value becomes too small.

• The PCM checks whether the fuel trim value is

within a specified range.

DESCRIPTIONS OF MONITOR METHODS
Right bank air/fuel learning value (long time fuel trim)

and air/fuel feedback integral value (short time
fuel trim) are too rich.

MONITOR EXECUTION
Continuous

MONITOR EXECUTION CONDITIONS (Other
monitor and Sensor)

Other Monitor (There is no temporary DTC stored

in memory for the item monitored below)

• Misfire monitor

Sensor (The sensor below is determined to be

normal)

• Volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

AK200950

B-03(GR)

B-02(GR)

B-01(GR)

CONNECTORS: B-01, B-02, B-03

HARNESS
CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-376

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 77°C

(171

°F).

• Volume airflow sensor output frequency is higher

than 100 Hz.

Judgment Criteria

• Long-term fuel trim has continued to be lower

than

−12.5 percent for 5 seconds.

• Short-term fuel trim has continued to be lower

than

−7.4 percent for 5 seconds.

Check Conditions

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 77°C

(171

°F).

• Volume airflow sensor output frequency is lower

than 100 Hz.

Judgment Criteria

• Long-term fuel trim has continued to be lower

than

−12.5 percent for 5 seconds.

• Short-term fuel trim has continued to be lower

than

−12.5 percent for 5 seconds.

LRN

: LONG-TERM TRIM

: SHORT-TERM TRIM

K0 : MAXIMUM LIMIT OF LONG-TERM TRIM
K1 : MAXIMUM LIMIT OF SHORT-TERM TRIM
K2 : MINIMUM LIMIT OF LONG-TERM TRIM
K3 : MINIMUM LIMIT OF SHORT-TERM TRIM

START

MONITORING

CONDITIONS

END

YES

LRN

> K0

MALFUNCTION

GOOD

LRN

< K2

< K3

> K1

CONTINUOUS FAILURE

FOR 5secs

AK302938

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-377

Check Conditions

• Engine coolant temperature is higher than 77°C

(171

°F).

• Under the closed loop air/fuel ratio control.

Judgment Criteria

• Long-term fuel trim has continued to be −12.5

percent for 5 seconds.

• Short-term fuel trim has continued to be −30.0

percent for 5 seconds.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 2

− Fuel Trim Monitor

P.13A-4

TROUBLESHOOTING HINTS (The most likely

causes for this code to be set are: )

• Volume airflow sensor failed.

• Injector (Number 1, 3, 5) failed.

• Incorrect fuel pressure.

• Engine coolant temperature sensor failed.

• Intake air temperature sensor failed.

• Barometric pressure sensor failed.

• Use of incorrect or contaminated fuel.

• PCM failed.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

STEP 1. Using scan tool MB991958, check data list item 12:
Volume Airflow Sensor.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Start the engine and run at idle.

(3) Set scan tool MB991958 to the data reading mode for item

12, Volume Airflow Sensor.

(4) Warm up the engine to normal operating temperature: 80

°C

to 95

°C (176°F to 203°F).

• When idling, between 17 and 43 Hz (between 3.5 and

7.5 gm/s).

• When 2,500 r/min, between 64 and 104 Hz (between

13.6 and 19.6 gm/s).

(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : YES: Go to Step 2.
NO : Refer to DTC P0101

− Volume Airflow Circuit

Range/Performance Problem

P.13A-33

, DTC P0102

− Volume Airflow Circuit Low Input

P.13A-42

AK302970

MB991911

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-378

STEP 2. Using scan tool MB991958, check data list item 13:
Intake Air Temperature Sensor.

(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991958 to the data reading mode for item

13, Intake Air Temperature Sensor.

• The intake air temperature and temperature shown with

the scan tool should approximately match.

(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : Go to Step 3.
NO : Refer to DTC P0111

− Intake Air Temperature Circuit

Range/Performance Problem

P.13A-95

, DTC P0112

− Intake Air Temperature Circuit Low Input

P.13A-102

, DTC P0113

− Intake Air Temperature

Circuit High Input

P.13A-107

STEP 3. Using scan tool MB991958, check data list item 21:
Engine Coolant Temperature Sensor.

(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991958 to the data reading mode for item

21, Engine Coolant Temperature Sensor.

• The engine coolant temperature and temperature

shown with the scan tool should approximately match.

(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : Go to Step 4.
NO : Refer to DTC P0116

− Engine Coolant Temperature

Circuit Range/Performance Problem

P.13A-114

, DTC

P0117

− Engine Coolant Temperature Circuit Low

Input

P.13A-125

, DTC P0118

− Engine Coolant

Temperature Circuit High Input

P.13A-130

AK302970

MB991911

MB991824

MB991827

AK302970

MB991911

MB991824

MB991827

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