Mitsubishi Colt Ralliart. Manual - part 692

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-93

FUNCTION

• The engine-ECU controls the injector activation 

time.

• The fuel injection amount from the injector 

depends on the injector activation time.

TROUBLE JUDGEMENT

Check Conditions

• Engine speed is more than 50 r/min and is less 

than 1,000 r/min.

• Throttle position sensor (main) output voltage is 

less than 1.0 V. 

• Not during fuel cut or forced injector-driving (actu-

ator test)

Judgement Criterion

• Injector coil surge voltage (battery voltage plus 2 

V) is not detected for 4 seconds.

PROBABLE CAUSES

• Failed No. 1 injector

• Open/short circuit or damage in No. 1 injector cir-

cuit, or loose connector contact

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III actuator test

• Item 01: No. 1 injector

OK: Idling state varies.

Q: Is the check result normal?

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points 

− 

How to Cope with Intermittent Malfunctions 

P.00-13

).

NO : 

Go to Step 2 .

STEP 2. Connector check: A-102 injector 
connector

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Repair or replace.

STEP 3. Perform resistance measurement at 
A-102 injector connector.

• Disconnect connector, and measure at injector 

side.

• Resistance between terminals No. 1 and No. 2.

OK: 10.5 

− 13.5 Ω (at 20°C)

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Replace No. 1 injector.

STEP 4. Perform voltage measurement at A-102 
injector connector.

• Disconnect connector and measure at harness 

side.

• Ignition switch: ON

• Voltage between terminal No. 1 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Go to Step 5 .

AK402088

M

1

2

AC

A-102(G)

Connector: A-102

Harness side 
connector

AK402088

M

1

2

AC

A-102(G)

Connector: A-102

Harness side 
connector

AK402088

M

1

2

AC

A-102(G)

Connector: A-102

Harness side 
connector

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-94

STEP 5. Connector check: B-106 engine control 
relay connector

Q: Is the check result normal?

YES : 

Check intermediate connectors A-17 and 

B-112 and repair if necessary. If 
intermediate connectors are normal, check 
and repair harness between B-106 (terminal 
No. 4) engine control relay connector and 
A-102 (terminal No.1) injector connector.

• Check power supply line for 

open/short circuit.

NO : 

Repair or replace.

STEP 6. Connector check: A-114 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Repair or replace.

3

2

1

4

AK402084

J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402088

M

1

2

AC

A-102(G)

Connector: A-102

Harness side 
connector

AK402745

6

4

2

5

3

1

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L

AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-95

STEP 7. Check harness between B-106 (terminal 
No. 4) engine control relay connector and A-102 
(terminal No. 1) injector connector.

NOTE: Before checking harness, check intermediate 
connectors A-17 and B-112, and repair if necessary.

• Check power supply line for damage.

Q: Is the check result normal?

YES : 

Go to Step 8 .

NO : 

Repair.

STEP 8. Connector check: A-114 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 9 .

NO : 

Repair or replace.

3

2

1

4

AK402084

J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402088

M

1

2

AC

A-102(G)

Connector: A-102

Harness side 
connector

AK402745

6

4

2

5

3

1

9

7

8

10

11

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66

L

AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-96

STEP 9. Check harness between A-102 (terminal 
No. 2) injector connector and A-114 (terminal No. 
8) engine-ECU connector.

• Check output line for open/short circuit and dam-

age.

Q: Is the check result normal?

YES : 

Go to Step 10 .

NO : 

Repair.

STEP 10. Perform signal wave pattern 
measurement at A-114 engine-ECU connector 
(using an oscilloscope).

• Disconnect engine-ECU connector, and connect 

special tool power plant ECU check harness 
(MB991987) and measure the voltage on the 
check connector.

• Engine: Idling

• Transmission: P range

• Voltage between terminal No. 8 and earth.

OK: Waveforms as shown in Inspection Pro-
cedure with Oscilloscope (Refer to 

P.13B-352

) should be displayed.

Q: Is the check result normal?

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points 

− 

How to Cope with Intermittent Malfunctions 

P.00-13

).

NO : 

Replace engine-ECU.

AK402088

M

1

2

AC

A-102(G)

Connector: A-102

Harness side 
connector

AK402745

6

4

2

5

3

1

9

7

8

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66

L

AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

AK402745

6

4

2

5

3

1

9

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66

L

AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

Main

Index

Group

TOC