Mitsubishi Galant 9G. Manual — part 1028

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-412

STEP 10. Check for harness damage between left bank
heated oxygen sensor (rear) connector B-24 (terminal No.
3) and PCM connector B-23 (terminal No. 137).

Q: Is the harness wire in good condition?

YES : Go to Step 11.
NO : Repair it. Then go to Step 12.

1

2

3

4

AK303079

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-24

AB

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

B-24 (GR)

127 126 125 124 123 122 121

133 132 131 130 129 128

140 139 138 137 136 135 134

146 145 144 143 142 141

153 152 151 150 149 148 147

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HARNESS CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-23

B-23

PCM

AB

AIR CLEANER

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-413

STEP 11. Check the trouble symptoms.

(1) Carry out a test drive with the drive cycle pattern. Refer to

Diagnostic Function

− OBD-II Drive Cycle − Procedure 6 −

Other Monitor

P.13B-6

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0161 set?

YES : Replace the PCM. Then go to Step 12.
NO : 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

P.00-14

.

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.13B-6

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0161 set?

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

NEXT>>

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-414

13B

DTC P0171: System too Lean (bank 1)

CAUTION

If DTC P0171 has been set, TCL related DTC
U1120 is also set. After P0171 has been diag-
nosed, don't forget to erase DTC U1120.

.

Fuel Trim Circuit

• Refer to DTC P0201− Injector Circuit − Cylinder 1

P.13B-481

, P0203

− Injector Circuit − Cylinder 3

P.13B-504

, P0205

− Injector Circuit − Cylinder 5

P.13B-527

.

CIRCUIT OPERATION

• Refer to DTC P0201

P.13B-481

, P0203

P.13B-504

, P

P.13B-527

− Injector Circuit.

.

TECHNICAL DESCRIPTION

• If a malfunction occurs in the fuel system, the fuel

trim value becomes too large.

• The PCM checks whether the fuel trim value is

within a specified range.

.

DESCRIPTIONS OF MONITOR METHODS

Right bank air/fuel learning value (long time fuel trim)

and air/fuel feedback integral value (short time
fuel trim) are too lean.

.

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)

• Misfire monitor

Sensor (The sensor below is determined to be

normal)

• Mass airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

.

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MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-415

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

• Engine coolant temperature is lower than 100°C

(212

°F) when the engine is started.

• Intake air temperature is lower than 60°C (140°F)

when the engine is started.

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 76°C

(169

°F).

• Mass airflow sensor output is 8 g/sec or more.

Judgment Criteria

• Long-term fuel trim has continued to be higher

than +12.5 percent for 5 seconds.

or

• Short-term fuel trim has continued to be higher

than +7.4 percent for 5 seconds.

K

LRN

: LONG-TERM TRIM

K

I

: SHORT-TERM TRIM

K0 : MAXIMUM LIMIT OF LONG-TERM TRIM
K1 : MAXIMUM LIMIT OF SHORT-TERM TRIM
K2 : MINIMUM LIMIT OF LONG-TERM TRIM
K3 : MINIMUM LIMIT OF SHORT-TERM TRIM

START

MONITORING

CONDITIONS

END

NO

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

YES

K

LRN

> K0

MALFUNCTION

GOOD

K

LRN

< K2

K

I

< K3

K

I

> K1

CONTINUOUS FAILURE

FOR 5secs

AK204050