Mitsubishi Galant. Manual — part 86

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-25

Driving

Hesitation Sag

" Hesitation " is the delay in
response of the vehicle speed
(engine speed). This occurs when
the accelerator is depressed in
order to accelerate from the speed
at which the vehicle is now
traveling, or a temporary drop in
vehicle speed (engine speed)
during such acceleration.
Serious hesitation is called " sag. "

Poor
acceleration

Poor acceleration is inability to obtain an acceleration corresponding to
the degree of throttle opening, even though acceleration is smooth or
the inability to reach maximum speed.

Stumble

Engine speed increase is delayed
when the accelerator pedal is
initially depressed for acceleration.

Shock

The feeling of a comparatively large impact or vibration when the
engine is accelerated or decelerated.

Surge

This is slight acceleration and deceleration feel usually felt during
steady, light throttle cruise. Most notable under light loads.

Knocking

A sharp sound during driving like a hammer striking the cylinder walls.

Stopping

Run on
("dieseling ")

The condition in which the engine continues to run after the ignition
switch is turned to off. Also called " dieseling. "

ITEMS

SYMPTOM

AKX01361

VEHICLE
SPEED

TIME

NORMAL

HESITATION

SAG

INITIAL
ACCELE-
RATOR
PEDAL
DEPRE-
SSION

AKX01361AB

AKX01362

VEHICLE
SPEED

TIME

NORMAL

STUMBLE

INITIAL
ACCEL-
ERATOR
PEDAL
DEP-
RESSION

IDLING

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L>

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DIAGNOSTIC TROUBLE CODE PROCEDURES

DTC P0101: Volume Air Flow Circuit Range/Performance Ploblem

AK000459

1 2 3 4 5 6 7

42 43
48 49 50 51 52 53 54 55 56 57

46

45

44

58 59

60 61 62 63

64 65 66

2

3 4

5 6

7 8

9

11 12 13 14 15 16 17 18 19 20

30

21 22 23

24 25

26 27 28 29

3132 33

34 35

RED

RED

-

WHITE

RED

-

WHITE

47

1

41

10

RED

-

WHITE

3 4

1 2

GREEN-BL

UE

BL

ACK

WHITE-GREEN

B-14

MFI
RELAY

BATTERY

VOLUME AIR
FLOW SENSOR

5V

19

7

57

65

4

5

3

C-39
(MU803784)

C-40
(MU803781)

POWERTRAIN CONTROL
MODULE(PCM)

3

4

1

2

A-21X

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L>

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CIRCUIT OPERATION

•

The volume air flow sensor power is supplied
from the MFI relay (terminal 1), and the ground is
provided on the PCM (terminal 57).

•

5-volt power is applied to the volume air flow
sensor output terminal (terminal 3) from the PCM
(terminal 65). The volume air flow sensor
generates a pulse signal when the output
terminal and ground are opened/closed (opened/
short).

TECHNICAL DESCRIPTION

•

While the engine is running, the volume air flow
sensor outputs a pulse signal which corresponds
to the volume of air flow.

•

The PCM checks whether the frequency of this
signal output by the volume air flow sensor while
the engine is running is at or above the set value.

DTC SET CONDITIONS

Check Conditions

•

Engine speed is higher than 500 r/min.

Judgement Criteria

•

Volume air flow sensor output frequency has
continued to be 3.3 Hz or lower for 2 seconds.

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

•

Volume air flow sensor failed.

•

Open or shorted volume air flow sensor circuit, or
loose connector.

•

PCM failed.

•

Air leak between volume air flow sensor and
throttle body.

DIAGNOSIS

Required Special Tools
MB991502: Scan Tool (MUT-II)

ACX02480

CONNECTOR : B-14

AC

VOLUME AIR
FLOW SENSOR

AK000280

CONNECTORS : C-39, C-40

C-39 C-40

PCM

AU

AK000555AB

CONNECTOR : A-21X

MFI RELAY

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L>

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STEP 1. Using scan tool MB991502, check data list item 12:
Volume Air Flow Sensor.

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK"(OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Start the engine and run at idle.
(3) Set scan tool MB991502 to the data reading mode for item

12, Volume Air Flow Sensor.

(4) Warm up the engine to normal operating temperature: 80

°

C to 96

°

C(176

°

F to 205

°

F).

•

The standard value during idling should be 10Hz or
more.

•

When the engine is revved, the frequency should
increase according to the increase in engine speed.

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

Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent.

Refer to GROUP 00, How to Use Troubleshooting/
Inspection Service Points(

P.00-8

).

NO : Go to Step 2.

STEP 2. Check the power supply voltage at volume air flow
sensor connector B-14 by backprobing.
(1) Do not disconnect the connector B-14.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 4 and ground by

backprobing.

•

Voltage should be battery positive voltage.

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

Q: Is the voltage normal?

YES : Go to Step 5.
NO : Go to Step 3.

STEP 3. Check the power supply voltage at volume air flow
sensor harness side connector B-14.
(1) Disconnect the connector B-14 and measure at the harness

side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 4 and ground.

•

Voltage should be battery positive voltage.

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

Q: Is the voltage normal?

YES : Go to Step 4.
NO : Repair harness wire between MFI relay connector A-

21X terminal 1 and volume air flow sensor connector
B-14 terminal 4 because of open circuit or short
circuit to ground. Then go to Step 13.

AC003081 AB

16 PIN

MB991502

AKX01514 AD

B-14 CONNECTOR
HARNESS SIDE VIEW

1 2 3 4 5 6 7

AKX01405

B-14 HARNESS
SIDE CONNECTOR

7 6 5 4 3 2 1

AC