Mitsubishi Galant. Manual — part 187

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-429

Example 2

•

Cause of problem
Open circuit in the line between the idle air control motor
and the PCM.

•

Wave pattern characteristics
Current is not supplied to the motor coil on the open circuit
side. (Voltage does not drop to 0 volt.) Furthermore, the
induced electromotive force wave pattern at the normal side
is slightly different from the normal wave pattern.

IGNITION COIL AND IGNITION POWER
TRANSISTOR

Required Special Tool:
MB991348: Test Harness Set
Measurement Method
1. Disconnect the ignition coil connector, and connect test

harness special tool, MB991348, in between. (All terminals
should be connected.)

2. Connect the oscilloscope probe to ignition coil connector

terminal 3.

Alternate method (Test harness not available)
Connect the oscilloscope probe to PCM terminals 11 (for

number 1

−

number 4), terminal 12 (for number 2

−

number

3) respectively.

Standard Wave Pattern

AKX01609

OPEN
CIRCUIT
SIDE

NORMAL
SIDE

AB

Observation conditions

Function

Special pattern

Pattern height

Low

Pattern selector

Display

Engine r/min

Approximately 1,200 r/min

AK000066 AB

OSCILLOSCOPE

OSCILLO
SCOPE
PLOBE

1 2 3

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-430

Wave Pattern Observation Points
Point: Condition of wave pattern build-up section and maximum

voltage (Refer to abnormal wave pattern examples 1 and 2.

Examples of Abnormal Wave Patterns
Example 1 (Wave pattern during engine cranking)

•

Cause of problem
Open-circuit in ignition primary circuit

•

Wave pattern characteristics
Top-right part of the build-up section cannot be seen, and
voltage value is approximately 2 volts too low.

CONDITION OF WAVE
PATTERN BUILD-UP
SECTION AND MAXIMUM
VOLTAGE

PROBABLE CAUSE

Rises from approximate 2
volts to approximate 4.5 volts
at the top-right

Normal

2-volt rectangular wave

Open-circuit in ignition primary
circuit

Rectangular wave at power
voltage

Ignition power transistor
malfunction

AK000068

AB

θ

(V)

T

REVOLUTION TIME CORRESPONDING
TO A CRANK ANGLE OF 180˚
COMPRESSION TOP DEAD CENTER

T:

75˚BTDC

5˚BTDC

6

CRANKSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN

4

2

0

6

T

1

θ

: SPARK

ADVANCE
ANGLE

IGNITION PERIOD

IGNITION POWER
TRANSISTOR
CONTROL SIGNAL
WAVE PATTERN

4

2

0

OFF

ON

DWELL
SECTION

TIME

T

1

: TIME COMPUTED BY THE ECM or PCM

Standard wave pattern

AKX01612

NORMAL WAVE
PATTERN

2V

AB

SPECIAL TOOLS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-431

Example 2 (Wave pattern during engine cranking)

•

Cause of problem
Malfunction in ignition power transister

•

Wave pattern characteristics
Power voltage results when the ignition power transistor is
ON.

SPECIA L TO O LS

M1131000600085

AKX01613

BATTERY
POSITION
VOLTAGE

NORMAL WAVE
PATTERN

AB

TOOL

TOOL NUMBER AND
NAME

SUPERSESSION

APPLICATION

MB991502
Scan tool <MUT-II>

MB991496-OD

•

Reading diagnostic
trouble code

•

MFI system inspection

MB991348
Test harness set

MB991348-01

•

Adjustment of throttle
position sensor

•

Inspection using an
oscilloscope

MB991709
Test harness set

MB991709-01

•

Inspection using an
oscilloscope

•

Inspection of idle air
control motor

MB991658
Test harness set

Tool not available

Inspection of heated
oxygen sensor

MD998463
Test harness (6 pin,
square)

MD998463-01

Inspection using an
oscilloscope

B991502

MB991348

MB991658

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-432

O N -VEH IC LE SERVIC E

COMPONENT LOCATION

M1131002100086

MD998464
Test harness (4 pin,
square)

MD998464-01

•

Inspection of heated
oxygen sensor

•

Inspection using an
oscilloscope

MD998478
Test harness (3 pin,
triangle)

MD998478-01

Inspection using an
oscilloscope

MD998709
Adaptor hose

MIT210196Measurement of fuel

pressure

MD998742
Hose adaptor

MD998742-01

MB991637
Fuel pressure gauge set

Tool not available

TOOL

TOOL NUMBER AND
NAME

SUPERSESSION

APPLICATION

MB991637

NAME

SYMBOL

NAME

SYMBOL

Air conditioning compressor clutch
relay

I

Idle air control motor

E

Camshaft position sensor

H

Ignition coil

L

Crankshaft position senso

J

Ignition failure sensor

A

Data link connector

Q

Injector

B

EGR solenoid

C

Manifold differential pressure sensor A

Engine coolant temperature sensor

G

Multiport fuel injection (MFI) relay/fu-
el pump relay

I

Engine speed detection connector

I

Evaporative emission purge sole-
noid

C

Park/neutral position switch

O