Mitsubishi Galant 9G. Manual — part 929

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-16

NOTE: *1 : Minimum value: The test fails if test value is less than this value.
NOTE: *2 : Maximum value: The test fails if test value is greater than this value.

08

Evaporation
leak monitor
(Very small
leak)

After PCM vacuumizes the fuel tank
and the fuel line and then the
specified time is passed, PCM
monitors the leak of fuel
evaporation gas through the fuel
tank differential pressure sensor to
check the reduction of vacuum in
the fuel tank.

EVAP Leak Mon. 0.5
mm Pressure Value
Test Result and Limit
Value (max.) kPa

× 0.032 kPa

09

Heated oxygen
sensor monitor
(Rich/Lean
Switching)
(Bank 1 Sensor
1)

PCM monitors the deteriorated
condition of the heated oxygen
sensor by checking the lean/rich
switching frequency of the heated
oxygen sensor.

HO2S B1 SENSOR 1
Rich/Lean Switching
Count
Test Result and Limit
Value (min.)

×1 count

0A

Heated oxygen
sensor monitor
(Rich/Lean
Switching)
(Bank 2 Sensor
1)

PCM monitors the deteriorated
condition of the heated oxygen
sensor by checking the lean/rich
Switching frequency of the heater
oxygen sensor.

HO2S B2 SENSOR 1
Rich/Lean Switching
Count
Test Result and Limit
Value (min.)

×1 count

0B

Heated oxygen
sensor monitor
(Voltage) (Bank
1 Sensor 2)

PCM checks the output voltage of
the heated oxygen sensor (rear) in
order to monitor whether the heated
oxygen sensor output is stuck.

HO2S B1 SENSOR2
Change in Volt
Test Result and Limit
Value (min.)

× 19.5mV

0C

Heated oxygen
sensor monitor
(Voltage) (Bank
2 Sensor 2)

PCM checks the output voltage of
the heated oxygen sensor (rear) in
order to monitor whether the heated
oxygen sensor output is stuck.

HO2S B2 SENSOR 2
Change in Volt
Test Result and Limit
Value (min.)

× 19.5mV

TEST
ID

MONITORING
ITEM

SIMPLE TECHNICAL
DESCRIPTION

INDICATION OF SCAN
TOOL

CONVERSION
COEFFICIENT IN
USING
GENERAL SCAN
TOOL

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-17

DIAGNOSTIC BY DIAGNOSTIC TEST MODE II
(INCREASED SENSITIVITY)

Required Special Tools:

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

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

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.
NOTE: When mode II is selected with MB991958, the Malfunc-
tion Indicator Lamp (SERVICE ENGINE SOON or Check
Engine Lamp) will light when the powertrain control module
(PCM) first detects the trouble (Note that this is only for emis-
sion-related trouble). At the same time, the relevant diagnostic
trouble codes will be registered. In respect to the comprehen-
sive component electrical faults (opens/shorts), the time for the
diagnostic trouble code to be registered after the fault occur-
rence is four seconds

→

one second. Therefore, the confirma-

tion of the trouble symptom and the confirmation after
completing repairs can be reduced. To return to the normal
mode I after mode II has been selected once, the ignition
switch must be turned "OFF" once or mode I must be rese-
lected with MB991958. The diagnostic trouble code, system
readiness test status and freeze frame data, etc., will be erased
when mode I is returned to, so record these before returning to
mode I.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Change the diagnostic test mode of the powertrain control

module to DIAGNOSTIC TEST MODE II (INCREASED
SENSITIVITY).

4. Road test the vehicle.
5. Read the diagnostic trouble code and repair the

malfunctioning part.

6. Turn the ignition switch to the "LOCK" (OFF) position.
7. Disconnect scan tool MB991958 from the data link

connector.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-18

ON-BOARD DIAGNOSTICS

The powertrain control module (PCM) monitors the input/output signals (some signals all the time and others
under specified conditions) of the PCM. When a malfunction continues for a specified time or longer after the
irregular signal is initially monitored, the PCM judges that a malfunction has occurred. After the PCM first
detects a malfunction, a diagnostic trouble code is recorded when the engine is restarted and the same mal-
function is re-detected. However, for items marked with a "*", a diagnostic trouble code is recorded on the first
detection of the malfunction. There are 126 diagnostic items. The diagnostic results can be read out with a
scan tool. Since memorization of the diagnostic trouble codes is backed up directly by the battery, the diag-
nostic results are memorized even if the ignition key is turned off. The diagnostic trouble codes will, however,
be erased when the battery terminal or the PCM connector is disconnected. In addition, the diagnostic trouble
code can also be erased by turning the ignition switch to ON and sending the diagnostic trouble code erase
signal from scan tool MB991958 to the PCM.
NOTE: If the sensor connector is disconnected with the ignition switch turned on, the diagnostic trouble code
is memorized. In this case, send the diagnostic trouble code erase signal to the PCM in order to erase the
diagnostic memory. The 126 diagnostic items are all indicated sequentially from the smallest code number.
The PCM records the engine operating condition when the diagnostic trouble code is set. This data is called
"Freeze-frame" data. This data can be read by using the scan tool, and can then be used in simulation tests
for troubleshooting. Data items are as follows:
NOTE: If the PCM detects multiple malfunctions, the PCM stores the "Freeze-frame" data for only the first
item that was detected. However, if the PCM detects a misfire or a fuel system malfunction, the PCM stores
the data by giving priority to the misfire or fuel system malfunction, regardless of the order in which the mal-
function was detects
NOTE: As for Diagnostic trouble code P1603, "Freeze-frame" data is not memorized.

MUT-III SCAN TOOL
DISPLAY

ITEM
NO.

DATA ITEM

UNIT or STATE

ECT SENSOR

21

Engine coolant temperature sensor

°C or °F

ENGINE LOAD

87

Calculated load value

%

ENGINE SPEED.

22

Crankshaft position sensor

r/min

IAT SENSOR

13

Intake air temperature sensor

°C or °F

IG. TIMING ADV

44

Ignition coils and ignition power

deg

LONG TRIM B1

81

Long-term fuel trim bank 1

%

LONG TRIM B2

83

Long-term fuel trim bank 2

%

MAP/MDP SNSR

32

Manifold absolute pressure sensor

kPa or in.Hg

SHORT TRIM B1

82

Short-term fuel trim bank 1

%

SHORT TRIM B2

84

Short-term fuel trim bank 2

%

SYS. STATUS B1

88

Fuel control system status bank1 (right)

• Open loop

• Closed loop

• Open loop-drive

condition

• Open loop-DTC set

• Closed loop-O

2

(rear)

failed

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-19

SYS. STATUS B2

89

Fuel control system status bank1 (left)

• Open loop

• Closed loop

• Open loop-drive

condition

• Open loop-DTC set

• Closed loop-O

2

(rear)

failed

TP SENSOR

8A

Throttle position sensor

%

VAF/MAF SNSR.

12

Mass airflow sensor

gm/s

VSS

24

Vehicle speed signal

km/h or mph

MUT-III SCAN TOOL
DISPLAY

ITEM
NO.

DATA ITEM

UNIT or STATE