Mitsubishi Eclipse. Manual — part 533

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-675

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CIRCUIT OPERATION

• A 5-volt voltage is supplied to the power terminal

of the fuel tank differential pressure sensor (ter-
minal 3) from the ECM (terminal 42) <M/T> or
PCM (terminal 46) <A/T>. The ground terminal
(terminal 2) is grounded with the ECM (terminal
49) <M/T> or PCM (terminal 57) <A/T>.

• A voltage proportional to the pressure in the fuel

tank is sent from the output terminal of the fuel
tank differential pressure sensor (terminal 1) to
the ECM (terminal 93) <M/T> or PCM (terminal
92) <A/T>.

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TECHNICAL DESCRIPTION

• To judge if the fuel tank differential pressure sen-

sor is defective, the ECM <M/T> or PCM <A/T>
monitors the fuel tank differential pressure sensor
output voltage.

• Based on the test conditions and judgment crite-

ria, the ECM <M/T> or PCM <A/T> judges if the
fuel tank differential pressure sensor output volt-
age is normal.

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DESCRIPTIONS OF MONITOR METHODS

• Detect malfunction if change of fuel tank differen-

tial pressure sensor output voltage during idling
stays large during specified go/stop operations.

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MONITOR EXECUTION

• Continuous.

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MONITOR EXECUTION CONDITIONS (Other
Monitor and Sensor)

Other Monitor (There is no temporary DTC stored

in memory for the item monitored below)

• Evaporative emission purge solenoid monitor

• Evaporative emission ventilation solenoid monitor

AC001741 AJ

CONNECTOR: C-28

AC001689AN

CONNECTORS: C-58, C-62<M/T>,
C-55, C-59 <A/T>

ECM <M/T>
OR
PCM <A/T>

C-62
<M/T>

C-58 <M/T>,
C-59 <A/T>

C-55
<A/T>

AC001991

CONNECTOR: C-90

CONNECTOR
BLOCK (LH)

AI

AC001787AD

CONNECTOR: D-16

AC103356

FUEL TANK

AD

CONNECTOR: D-18
FUEL TANK DIFFERENTIAL
PRESSURE SENSOR

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-676

Sensor (The sensors below are determined to be

normal)

• Volume airflow sensor

• Barometric pressure sensor

• Intake air temperature sensor

• Engine coolant temperature sensor

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LOGIC FLOW CHARTS (Monitor Sequence)

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DTC SET CONDITIONS

Test Conditions: Electrical noise

• Throttle valve is closed.

• Vehicle speed is 1.5 km/h (0.9 mph) or less.

START

YES

NO

NO

OFF-IDLING CONDITION

IDLING CONDITION?

F1 = 0

END

NO

NO

YES

YES

MALFUNCTION

F1 > 20

SPECIFIED TIMES

MONITORED

FTPS OUTPUT

VOLTAGE > 0.2V

FLUCTUATION

NO

YES

YES

F1 = F1 + 1

GOOD

YES

NO

OFF-IDLING CONDITION

AC210307

RATIONALITY - NOISE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-677

Judgment Criteria

• The event that the output voltage from the fuel

tank differential pressure sensor changes by 0.2
volts or more (i.e. sudden pressure fluctuation) is
counted at least twenty times during one engine
idling, and then consecutively eight times during
normal driving condition.
NOTE: If the number of the sudden pressure fluc-
tuation does not reach twenty during one engine
idling, the counter will be reset to zero. If the igni-
tion switch is turned off, it will be also reset to
zero.
NOTE: The conditions for deviating from idling
operation are as follows:

.

•

Engine speed is higher than 2,500 r/min.

•

Vehicle speed is 15 km/h (9.3 mph) or more.

•

Volumetric efficiency is 55 percent or more.

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OBD-ll DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-ll Drive Cycle −

Procedure 1

− Evaporative Emission System Leak

Monitor

P.13B-7

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

• Fuel tank differential pressure sensor failed.

• Damaged harness in the fuel tank differential

pressure sensor circuit.

• ECM <M/T> or PCM <A/T> failed.

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OVERVIEW OF TROUBLESHOOTING

• DTC P0451 can be set if either of the following

conditions occur:

1. Faulty fuel differential pressure sensor,

related circuit, or ECM <M/T> or PCM <A/T>.

• To check a system blockage, do a performance

test which uses a mechanical vacuum gauge and
scan tool MB991958 set on the fuel tank differen-
tial pressure sensor (TANK PRS SNSR 73.) The
mechanical gauge reading is used to verify scan
tool MB991958 reading. A comparison of the
mechanical gauge to scan tool MB991958 deter-
mines the problem in the system.

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DIAGNOSIS

Required Special Tools:

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

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

• MB991658: Test Harness Set

• MB991709: Test Harness Set

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-678

STEP 1. Using scan tool MB991958, check data list item 73:
Fuel Tank Differential Pressure 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) Disconnect hose I from the evaporative emission canister

side, and plug the hose from which the pipes have been
disconnected.

(3) Turn the ignition switch to the "ON" position.
(4) Remove the fuel cap.
(5) Set scan tool MB991958 to the data reading mode for item

73, Fuel Tank Differential Pressure Sensor.

• The fuel tank pressures should be −1.5 to 1.5 kPa

(

−0.443 to 0.443 inHg.)

(6) Connect an evaporative emission system pressure pump to

the fuel filler neck, and apply pressure.

• The scan tool reading should increase.

(7) Turn the ignition switch to the "LOCK" (OFF) position. Then

disconnect scan tool MB991958.

Q: Is the scan tool reading within the specified value?

YES : Go to Step 22.
NO : Go to Step 2.

AC303127

AB

MB991911

16-PIN

MB991827

MB991824

AC002072 AB

HOSE I

AC000186