Mitsubishi Montero (2004+). Manual — part 213
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-339
.
CIRCUIT OPERATION
• A voltage corresponding to the oxygen concen-
tration in the exhaust gas is sent to the PCM (ter-
minal No. 116) from the output terminal
(terminalNo. 4) of the left bank heated oxygen
sensor (rear).
• Terminal No. 2 of the left bank heated oxygen
sensor (rear) is grounded with PCM (terminal No.
96).
.
TECHNICAL DESCRIPTION
• The output signal of the left bank heated oxygen
sensor (front) is compensated by the output sig-
nal of the left bank heated oxygen sensor (rear).
• The PCM checks for an open circuit in the left
bank heated oxygen sensor (rear) output line.
.
DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor (rear) output voltage
stays low when air/fuel ratio is forced to be rich.
The above procedure is repeated when oxygen
sensor is inactive.
.
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)
• Heated oxygen sensor heater (front) monitor
• Heated oxygen sensor heater (rear) monitor
• Air/fuel ratio feedback monitor
AK201279
CONNECTOR: C-15
C-15(B)
AD
LEFT BANK
HEATED OXYGEN
SENSOR (REAR)
AK201049
CONNECTOR: D-116
D-116
AC
AK201052
E-112
AB
CONNECTOR: E-112
AK201038AF
CONNECTOR: D-135
PCM
D-135(GR)
AK201049
D-14
AB
CONNECTOR: D-14
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-340
Sensor (The sensor below is determined to be
normal)
• Volume airflow sensor
• Engine coolant temperature sensor
• Intake air temperature sensor
• Barometric pressure sensor
.
DTC SET CONDITIONS
Logic Flow Chart
START
V
F
> =4.5V
2secs HAS PASSED
YES
YES
YES
NO
NO
NO
MALFUNCTION
MONITORING
CONDITIONS
YES
NO
MONITORING
CONDITIONS
+5V ON
AK302935
V
F
< 0.15V
10secs HAS PASSED
YES
YES
NO
NO
END
MALFUNCTION
GOOD
MODULATE A/F CONDITION TO RICH
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-341
Check Conditions
• 3 minutes or more have passed since the engine
starting sequence was completed.
• Left bank heated oxygen sensor (rear) signal
voltage has continued to be 0.15 volt or lower.
• Engine coolant temperature is higher than 76°C
(169
°F).
• Engine speed is higher than 1,200 r/min.
• Volumetric efficiency is higher than 25 percent.
• Volume airflow sensor output frequency is higher
than 100 Hz.
• At least 20 seconds have passed since fuel shut
off control was canceled.
• Monitoring time: 10 seconds.
Judgement Criteria
• Making the air/fuel ratio 15 percent for 10 sec-
onds richer does not result in raising the left bank
heated oxygen sensor (rear) output voltage
beyond 0.15 volt.
.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function
− OBD-II Drive Cycle −
Procedure 6
.
.
TROUBLESHOOTING HINTS (The most likely
causes for this code to be set are: )
• Left bank heated oxygen sensor (rear) failed.
• Short circuit in left bank heated oxygen sensor
(rear) output line.
• 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
• MB998464: Test Harness Set
STEP 1. Using scan tool MB991958, check data list item 59:
Heated Oxygen Sensor Bank 2, Sensor 2 (left bank).
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
59, Heated Oxygen Sensor Bank 2, Sensor 2 (left rear).
• Warming up the engine. When the engine is revved, the
output voltage should repeat 0 volt and 0.6 to 1.0 volt
alternately.
(4) 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.
AK302970
AB
MB991911
MB991824
MB991827
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-342
STEP 2. Check the left bank heated oxygen sensor (rear).
(1) Disconnect the left bank heated oxygen sensor (rear)
connector C-15 and connect test harness special tool
MD998464 to the connector on the left bank heated oxygen
sensor (rear) side.
(2) Warm up the engine until engine coolant temperature
reaches 80
°C (176°F) or higher.
(3) Perform a racing for 5 minutes or more with the engine
speed of 4,500 r/min.
(4) Connect a digital voltage meter between terminal No. 2
(black clip of special tool) and terminal No. 4 (white clip of
special tool).
(5) While repeatedly revving the engine, measure the left bank
heated oxygen sensor (rear) output voltage.
Standard value: 0.6
− 1.0 volt
CAUTION
• Be very careful when connecting the jumper wire;
incorrect connection can damage the left bank heated
oxygen sensor (rear).
• Be careful the heater is broken when voltage of beyond
8 volts is applied to the left bank heated oxygen sensor
(rear) heater.
NOTE: If the sufficiently high temperature [of approximate
400
°
C (752
°
F) or more] is not reached although the left
bank heated oxygen sensor (rear) is normal, the output volt-
age would be possibly low although the rich air/fuel ratio.
Therefore, if the output voltage is low, use a jumper wire to
connect the terminal No. 1 (red clip of special tool) and the
terminal No. 3 (blue clip of special tool) of the left bank
heated oxygen sensor (rear) with the positive terminal and
the negative terminal of 8 volts power supply respectively,
then check again.
Q: Is the voltage between 0.6 and 1.0 volt?
YES : Go to Step 3.
NO : Replace the left bank heated oxygen sensor (rear).
Then go to Step 5.
AK201280
1
2
3
4
CONNECTOR: C-15
C-15(B)
AC
HARNESS
CONNECTOR:
COMPONENT SIDE
LEFT BANK
HEATED OXYGEN
SENSOR (REAR)
AKX01624
HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR
MD998464
WHITE
BLACK
AL
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