Mitsubishi Galant 9G. Manual — part 989
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>
13B-256
.
CIRCUIT OPERATION
• A voltage corresponding to the oxygen concen-
tration in the exhaust gas is sent to the PCM (ter-
minal No. 97) from the output terminal (terminal
No. 4) of the right bank heated oxygen sensor
(rear).
• Terminal No. 2 of the right bank heated oxygen
sensor (rear) is grounded with PCM (terminal No.
69).
.
TECHNICAL DESCRIPTION
• The output signal of the right bank heated oxygen
sensor (front) is compensated by the output sig-
nal of the right bank heated oxygen sensor (rear).
• The PCM checks for an open circuit in the right
bank heated oxygen sensor (rear) output line.
.
DESCRIPTIONS OF MONITOR METHODS
Right bank heated oxygen sensor (rear) circuit is
switched to 5 volts intentionally when oxygen
sensor output is low, and detects the malfunction
if the output voltage changes to equal or greater
than 4.5 volts. 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
Sensor (The sensor below is determined to be
normal)
• Mass airflow sensor
• Engine coolant temperature sensor
• Intake air temperature sensor
• Barometric pressure sensor
.
AK303063
THROTTLE BODY
RIGHT BANK
HEATED OXYGEN
SENSOR (REAR)
CONNECTOR: B-08
B-08 (GR)
AB
AK303013
CONNECTORS: B-21, B-22
PCM
AB
AIR CLEANER
B-22 (B)
B-21 (B)
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>
13B-257
DTC SET CONDITIONS
Logic Flow Chart
.
Check Conditions
• 3 minutes or more have passed since the engine
starting sequence was completed.
• Right 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.
• Monitoring time: 7 seconds.
START
V
F
> =4.5V
2secs HAS PASSED
YES
YES
YES
NO
NO
NO
MALFUNCTION
MONITORING
CONDITIONS
YES
NO
MONITORING
CONDITIONS
+5V ON
AK401414
V
F
< 0.15V
8secs HAVE 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) <3.8L ENGINE>
13B-258
Judgment Criteria
• Input voltage supplied to the PCM interface circuit
is higher than 4.5 volts when 5 volts is applied to
the right bank heated oxygen sensor (rear) output
line via a resistor.
.
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: )
• Right bank heated oxygen sensor (rear) failed.
• Open or shorted circuit in right bank heated oxy-
gen sensor (rear) output line or harness damage.
• Open circuit in right bank heated oxygen sensor
(rear) ground line or harness damage.
• Connector damage.
• PCM failed.
DIAGNOSIS
Required Special Tools:
• MB991958: Scan tool (MUT-III Sub Assembly)
• MB991824: V.C.I.
• MB991827: USB Cable
• MB991910: Main Harness A
• MB991316: Test Harness
• MB991923: Power Plant ECU Check Harness
STEP 1. Using scan tool MB991958, check data list item 69:
Heated Oxygen Sensor Bank 1, Sensor 2 (right rear).
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
69, Heated Oxygen Sensor Bank 1, Sensor 2 (right 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
− How to
Cope with Intermittent Malfunctions
.
NO : Go to Step 2.
AC305412
AB
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>
13B-259
STEP 2. Measure the sensor output voltage at right bank
heated oxygen sensor (rear) connector B-08 by
backprobing
(1) Do not disconnect the connector B-08.
(2) Start the engine and run at idle.
(3) Measure the voltage between terminal No. 4 and ground by
backprobing.
• 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 measured voltage within the specified range?
YES : Go to Step 3.
NO : Go to Step 7.
AK303064
1
2
3
4
THROTTLE BODY
RIGHT BANK
HEATED OXYGEN
SENSOR (REAR)
CONNECTOR: B-08
B-08 (GR)
AB
HARNESS
CONNECTOR:
COMPONENT SIDE
1 2
4
3
AK303065
B-08 HARNESS
CONNECTOR:
HARNESS SIDE
AB
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