Mitsubishi Eclipse. Manual - part 243

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-465

STEP 11. Check for harness damage between EGR vacuum
regulator solenoid valve connector B-31 (terminal No. 2)
and ECM connector C-49 (terminal No. 6) <M/T> or PCM
connector C-50 (terminal No. 6) <A/T>.

AK300406

CONNECTOR: B-31

B-31 (BR)

HARNESS CONNECTOR:
COMPONENT SIDE

AK300413

CONNECTOR: C-49 <M/T>

C-49 (G)

HARNESS CONNECTOR:
COMPONENT SIDE

AK300414

C-50 (GR)

CONNECTOR: C-50 <A/T>

HARNESS CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L>

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NOTE: Check harness after checking intermediate connector
B-13.If intermediate connectors is damaged, repair or replace
them.Refer to GROUP 00E, Harness Connector Inspection

P.00E-2

.Then go to Step 12.

Q: Is the harness wire in good condition?

YES : Replace the ECM or PCM. Then go to Step 12.
NO : Repair it. Then go to Step 12.

STEP 12. 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 6 −

Other Monitor

P.13A-5

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0403 set?

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

DTC P0421: Warm Up Catalyst Efficiency Below Threshold

TECHNICAL DESCRIPTION

• The signal from the rear heated oxygen sensor

differs from the front heated oxygen sensor. That
is because the catalytic converter purifies
exhaust gas. When the catalytic converter has
deteriorated, the signal from the front heated oxy-
gen sensor becomes similar to the rear heated
oxygen sensor.

• The ECM <M/T> or PCM <A/T> compares the

output of the front and rear heated oxygen sensor
signals.

DESCRIPTIONS OF MONITOR METHODS
Front and rear oxygen sensor rich/lean switching fre-

quencies are nearly equal.

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 (front) monitor

• Heated oxygen sensor (rear) monitor

• Heated oxygen sensor heater (front) monitor

• Heated oxygen sensor heater (rear) monitor

• Misfire monitor

• Fuel system monitor

• Air/fuel ratio feedback 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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-467

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• Engine speed is lower than 3,000 r/min.

• Volume airflow sensor output frequency is at

between 63 and 169 Hz.

• The throttle valve is open.

• More than 3 seconds has elapsed after the three

above-mentioned conditions have been met.

• Intake air temperature is higher than −10°C

(14

°F).

• Barometric pressure is higher than 76 kPa (22.4

in.Hg).

• Under the closed loop air/fuel ratio control.

• Vehicle speed is 1.5 km/h (1 mph) or more.

• The ECM <M/T> or PCM <A/T> monitors for this

condition for 7 cycles of 10 seconds each during
the drive cycle.

• Short-term fuel trim is at between −25 and +25

percent.

• The cumulative volume airflow sensor output fre-

quency is higher than 4,000 Hz.

Judgment Criteria

• The heated oxygen sensor (rear) signal fre-

quency divided by heated oxygen sensor (front)
signal frequency = 0.8 or more.

OBD-ll DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-ll Drive Cycle −

Procedure 3

− Catalytic Converter Monitor

P.13A-5

TROUBLESHOOTING HINTS (The most likely
causes for this code to be set are: )

• Catalytic converter deteriorated.

• Heated oxygen sensor failed.

• ECM failed. <M/T>

• PCM failed. <A/T>

DIAGNOSIS

Required Special Tools:

• MB991958 (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

START

MONITORING

CONDITIONS

Rf > R0

MALFUNCTION

GOOD

END

YES

CALCULATE AVERAGE FREQUENCY

RATIO (Rf = Fr/Ff) OF SPECIFIED TIMES

R0: AVERAGE THRESHOLD VALUE.
R1: REAL TIME THRESHOLD VALUE.

AK204058

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-468

STEP 1. Check the exhaust leaks.
Q: Are there any abnormalities?

YES : Repair it. Then go to Step 7.
NO : Go to Step 2.

STEP 2. Using scan tool MB991958, check data list item 59:
Heated Oxygen Sensor (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

59, Heated Oxygen Sensor (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 : Go to Step 3.
NO : Refer to, DTC P0136

− Heated Oxygen Sensor Circuit

(sensor 2)

P.13A-277

, DTC P0137

− Heated Oxygen

Sensor Circuit Low Voltage (sensor 2)

P.13A-294