Mitsubishi Montero (2004+). Manual — part 139
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-43
.
CIRCUIT OPERATION
• The volume airflow sensor power is supplied from
the MFI relay (terminal No. 1), and the ground is
provided on the PCM (terminal No. 88).
• 5-volt power is applied to the volume airflow sen-
sor output terminal (terminal No. 3) from the PCM
(terminal No. 63). The volume airflow sensor gen-
erates a pulse signal when the output terminal
and ground are opened/closed (opened/short).
.
TECHNICAL DESCRIPTION
• While the engine is running, the volume airflow
sensor outputs a pulse signal which corresponds
to the volume of air flow.
• The PCM checks whether the frequency of this
signal output by the volume airflow sensor while
the engine is running is at or above the set value.
.
DESCRIPTIONS OF MONITOR METHODS
• An open or short circuit is detected while monitor-
ing the output frequency of the volume airflow
sensor.
.
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)
• Not applicable
Sensor (The sensor below is determined to be
normal)
• Not applicable
.
AK201039
MFI RELAY
B-22X
AB
CONNECTOR: B-22X
AK200940AD
B-48(B)
CONNECTOR: B-48
VOLUME AIRFLOW
SENSOR
AK201038AH
CONNECTORS: D-133, D-134
PCM
D-134(GR)
D-133(GR)
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-44
DTC SET CONDITIONS
Logic Flow Chart
Check Conditions
• Engine speed is higher than 500 r/min.
Judgement Criteria
• Volume airflow sensor output frequency has con-
tinued to be 3.3 Hz or lower for 2 seconds.
.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function
− OBD-II Drive Cycle −
Procedure 6
− Other Monitor
.
.
TROUBLESHOOTING HINTS (The most likely
causes for this code to be set are: )
• Volume airflow sensor failed.
• Open or shorted volume airflow sensor circuit,
harness damage, or connector damage.
• PCM failed.
DIAGNOSIS
Required Special Tools:
• MB991958: Scan Tool (MUT-III Sub Assembly)
• MB991824: V.C.I.
• MB991827: USB Cable
• MB991911: Main Harness B
START
MONITORING
CONDITIONS
END
NO
NO
NO
YES
YES
YES
MALFUNCTION
GOOD
OUTPUT FREQUENCY
< 3.3Hz
CONTINUOUS
FAILURE FOR 2 secs
AK302919
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-45
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).
• The standard value during idling should be 10 Hz or
more.
• When the engine is revved, the frequency should
increase according to the increase in engine speed.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES : It can be assumed that this malfunction is intermittent.
Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points
NO : Go to Step 2.
STEP 2. Measure the power supply voltage at volume
airflow sensor connector B-48 by backprobing.
(1) Do not disconnect the connector B-48.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No.4 and ground by
backprobing.
• Voltage should be battery positive voltage.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts)
present?
YES : Go to Step 5.
NO : Go to Step 3.
AK302970
AB
MB991911
MB991824
MB991827
AK200937
3
4
5
1
2
6
7
AB
HARNESS
CONNECTOR:
COMPONENT SIDE
CONNECTOR: B-48
B-48(B)
AKX01514
6 7
1 2 3 4 5
AKX01514
AK
B-48 HARNESS
CONNECTOR:
HARNESS SIDE
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-46
STEP 3. Measure the power supply voltage at volume
airflow sensor harness side connector B-48.
(1) Disconnect the connector B-48 and measure at the harness
side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 4 and ground.
• Voltage should be battery positive voltage.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts)
present?
YES : Go to Step 4.
NO : Repair harness wire between MFI relay connector
B-22X (terminal No. 1) and volume airflow sensor
connector B-48 (terminal No. 4) because of open
circuit or short circuit to ground. Then go to Step 13.
STEP 4. Check connector B-48 at the volume airflow
sensor for damage.
Q: Is the connector in good condition?
YES : Repair harness wire between MFI relay connector
B-22X (terminal No. 1) and volume airflow sensor
connector B-48 (terminal No. 4) because of harness
damage. Then go to Step 13.
NO : Repair or replace it. Refer to GROUP 00E, Harness
Connector Inspection
. Then go to Step 13.
STEP 5. Check connector B-48 at volume airflow sensor
for damage.
Q: Is the connector in good condition?
YES : Go to Step 6.
NO : Repair or replace it. Refer to GROUP 00E, Harness
Connector Inspection
. Then go to Step 13.
AK200937
3
4
5
1
2
6
7
AB
HARNESS
CONNECTOR:
COMPONENT SIDE
CONNECTOR: B-48
B-48(B)
AKX01405
B-48 HARNESS CONNECTOR:
COMPONENT SIDE
AK
1
2
3
4
5
6
7
AK200937
3
4
5
1
2
6
7
AB
HARNESS
CONNECTOR:
COMPONENT SIDE
CONNECTOR: B-48
B-48(B)
AK200937
3
4
5
1
2
6
7
AB
HARNESS
CONNECTOR:
COMPONENT SIDE
CONNECTOR: B-48
B-48(B)
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