Mitsubishi Montero (2004+). Manual — part 268

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-559

FUEL TANK
DIFFERENTIAL
PRESSURE
SENSOR

POWERTRAIN CONTROL
MODULE (PCM)

AC309251

Fuel Tank Differential Pressure Sensor Circuit

AB

FUEL TANK
DIFFERENTIAL
PRESSURE
SENSOR

POWERTRAIN CONTROL
MODULE (PCM)

AC309251

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-560

.

CIRCUIT OPERATION

• The PCM (terminal 97) supplies a 5-volt refer-

ence signal to the fuel tank differential pressure
sensor (terminal 3). The fuel tank differential
pressure sensor (terminal 2) is grounded through
the PCM (terminal 96).

• The fuel tank differential pressure sensor (termi-

nal 1) returns a voltage signal to the PCM (termi-
nal 82) that is proportional to the pressure in the
fuel tank.

.

TECHNICAL DESCRIPTION

• The PCM monitors the fuel tank differential pres-

sure sensor output voltage.

• The PCM determines whether the fuel tank differ-

ential pressure sensor signal voltage is within
normal operating parameters.

.

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.

.

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)

• Evaporative emission purge solenoid monitor

• Evaporative emission ventilation solenoid monitor

AC203998

CONNECTOR: D-112

AB

D-112

AC203993

CONNECTORS: D-134, D-135

AB

D-134
(GR)

D-135
(GR)

PCM

AC203999

CONNECTORS: E-111, E-113

AB

E-113

E-111

AC204000

CONNECTOR: F-07

AB

F-07 (B)

ACX00218

CONNECTOR : G-05

AQ

G-05 (B)

SECOND SEAT UNDER
SERVICE HOLE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-561

Sensor (The sensors below are determined to be

normal)

• Volume airflow sensor

• Barometric pressure sensor

• Intake air temperature sensor

• Engine coolant temperature sensor

.

LOGIC FLOW CHARTS (Monitor Sequence)

.

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

AC306647

RATIONALITY - NOISE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-562

DTC SET CONDITIONS

Check Conditions

• Throttle valve is closed.

• Vehicle speed is 1.5 km/h (0.93 mph) or less.

Judgment Criteria

• If the voltage signal from the fuel tank differential

pressure sensor changes by 0.2 volt or more,
DTC P0451 will set. The code may also set if a
sudden pressure fluctuation occurs twenty times
while the engine is idling, and then eight consec-
utive times during normal driving.
NOTE: If the number of sudden pressure fluctua-
tions does not reach twenty during any one
period of engine idling, or if the ignition switch is
turned OFF, the counter will reset to zero.
NOTE: The conditions for deviating from idling
operation are as follows:

.

•

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

•

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

•

Volumetric efficiency is 55 percent or greater.

.

OBD-ll DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-ll Drive Cycle −

Procedure 1

− Evaporative Emission System Leak

Monitor

P.13A-4

.

.

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

• Malfunction of the fuel tank differential pressure

sensor.

• A damaged harness in the fuel tank differential

pressure sensor circuit.

• Malfunction of the PCM.

.

OVERVIEW OF TROUBLESHOOTING

• DTC P0451 can be set by a faulty fuel tank differ-

ential pressure sensor or related circuit, or PCM
failure.

• To check for 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 with the reading on scan tool
MB991958 will locate a problem in the system.

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