Mitsubishi Eclipse / Eclipse Spyder (2000-2002). Service and repair manual — part 166

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-363

INSPECTION PROCEDURE 8: Unstable Idle (Rough Idle, Hunting).

COMMENT

•

In cases such as the above, the cause is
probably the air/fuel mixture or idle air control
motor. Other systems affecting idle quality
include the ignition system and compression.

TROUBLESHOOTING HINTS (The most likely
causes for this case:)

•

Malfunction of the ignition system.

•

Malfunction of air/fuel ratio control system.

•

Malfunction of the IAC system.

•

Malfunction of the evaporative emission purge
solenoid system.

•

Poor compression pressure.

•

Vacuum leak.

•

Malfunction of the EGR solenoid system.

DIAGNOSIS

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

STEP 1. Check if the battery terminal is disconnected

Q: Has the battery terminal been disconnected lately?

YES : Start the engine and let it run at idle for approximate

10 minutes after engine warm up.Then, if a
malfunction occurs, go to Step 2.

NO : Go to Step 2.

STEP 2. Using scan tool MB991502, read the diagnostic
trouble code (DTC).

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch is to the "LOCK" (OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the DTC is output?

YES : Refer to, Diagnostic Trouble Code Chart (

P.13A-20

).

NO : Go to Step 3.

STEP 3. Check the engine idling state.

Q: Is it hunting remarkably?

YES : Go to Step 4.
NO : Go to Step 5.

AKX01177

16 PIN

MB991502

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-364

STEP 4. Check the following items.
(1) Carry out the following cleaning.

a. Clean the throttle valve area (refer to

P.13A-472

).

(2) After cleaning, confirm that the malfunction symptom is

eliminated.

Q: Is the malfunction symptom resolved?

YES : The check is completed.
NO : Check the following items, and repair or replace the

defective items.

a. Broken intake manifold gasket.
b. Broken air intake hose.

c. Broken vacuum hose.

d. Positive crankcase ventilation valve does not

operate.

Then confirm that the malfunction symptom is

eliminated.

STEP 5. Check the idle air control (IAC) motor operation
sound.
(1) Check that the engine coolant temperature is 20

°

C (68

°

F)

or below.

NOTE: Disconnecting the engine coolant temperature
sensor connector and connecting the harness side of the
connector to another engine coolant temperature sensor
that is at 20

°

C (68

°

F) or below is also okay.

(2) Check the operation sound of the IAC motor can be heard

after the ignition is switched to the "ON" position (but
without starting the engine).

•

An operation sound is heard.

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

Q: Did you hear the operation sound?

YES : Go to Step 6.
NO : Refer to, DTC P0506

−

Idle Control System RPM

Lower Than Expected (

P.13A-290

), DTC P0507

−

Idle

Control System RPM Higher Than Expected (

P.13A-

299

).

ACX02519 AI

IDLE AIR
CONTROL MOTOR

CONNECTOR:B-34

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-365

STEP 6. Using scan tool MB991502, check actuator test
items 01, 02, 03, 04: Injector.

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) Turn the ignition switch to the "ON" position.
(3) Check following items in the actuator test. Refer to, Actuator

Test Reference Table (

P.13A-450

).

a. Item 01, 02, 03, 04: Injector.

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

Q: Is the actuator operating properly?

YES : Go to Step 7.
NO : Refer to, DTC P0201, P0202, P0203, P0204

−

Injector Circuit Malfunction(

P.13A-161

).

STEP 7. Using scan tool MB991502, check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the data list. Refer to, Data List

Reference Table (

P.13A-442

).

a. Item 13: Intake Air Temperature Sensor.
b. Item 25: Barometric Pressure Sensor.

c. Item 21: Engine Coolant Temperature Sensor.

d. Item 59: Heated Oxygen Sensor (rear)
e. Item 11: Heated Oxygen Sensor (front)

f. Item 27: Power Steering Pressure Switch.

g. Item 28: A/C Switch

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

Q: Are they operating properly?

YES : Go to Step 8.
NO : Repair or replace. Then confirm that the malfunction

symptom is eliminated.

STEP 8. Using scan tool MB991502, check actuator test.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the actuator test. Refer to,

Actuator Test Reference Table (

P.13A-450

).

a. Item 08: Evaporative Emission Purge Solenoid.
b. Item 10: EGR Solenoid.

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

Q: Are they operating properly?

YES : Go to Step 9.
NO : Repair or replace. Then confirm that the malfunction

symptom is eliminated.

AKX01177

16 PIN

MB991502

AB

AKX01177

16 PIN

MB991502

AB

AKX01177

16 PIN

MB991502

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-366

STEP 9. Using scan tool MB991502, check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the data list. Refer to, Data List

Reference Table (

P.13A-442

).

a. Item 45: Idle Air Control Motor Position.

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

Q: Is the actuator operating properly?

YES : Go to Step 10.
NO : Adjust the basic idle speed. Refer to, Basic Idle

Speed Adjustment (

P.13A-474

). After adjusting,

confirm.

STEP 10. Using scan tool MB991502, check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items of the data list. Refer to, Data List

Reference Table (

P.13A-442

).

a. Item 11: Heated Oxygen Sensor (front)

•

Voltage should fluctuate between 0

−

0.4 volts and 0.6 -

1.0 volts while idling after the engine has been warmed.

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

Q: Is the sensor operating properly?

YES : Go to Step 12.
NO : Go to Step 11.

STEP 11. Check the fuel pressure.
Refer to, Fuel Pressure Test (

P.13A-475

).

Q: Is the fuel pressure normal?

YES : a. Check the following items, and repair or replace

the defective items.

•

Vacuum leak.

•

Broken intake manifold gasket.

•

Broken air intake hose.

•

Broken vacuum hose.

•

Positive crankcase ventilation valve does not
operate.

b. Injector clogged.

Then confirm that the malfunction symptom is
eliminated.

NO : Repair or replace. Then confirm that the malfunction

symptom is eliminated.

AKX01177

16 PIN

MB991502

AB

AKX01177

16 PIN

MB991502

AB