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

TSB Revision

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