Mitsubishi Lancer Evolution X. Manual - part 419

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-741

STEP 1. Using scan tool MB991958, read the diagnostic
trouble code (DTC).

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.
(1) Connect scan tool MB991958 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 any DTC set?

YES : Refer to Diagnostic Trouble Code Chart

P.13A-48

NO : Go to Step 2.

STEP 2. Inspection of throttle body (throttle valve area) for
dirtiness.
Q: Is the throttle valve area dirty?

YES : Refer to Throttle Body (Throttle Valve Area) Cleaning

P.13A-865

NO : Go to Step 3.

STEP 3. Using scan tool MB991958, 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-818

a. Item 11: Accelerator Pedal Position Sensor (main).
b. Item 12: Accelerator Pedal Position Sensor (sub).

c. Item 13: Throttle Position Sensor (main).

d. Item 15: Throttle Position Sensor (sub).

(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are they operating properly?

YES : Go to Step 4.
NO : Repair or replace it. Then confirm that the malfunction

symptom is eliminated.

AC608435

Data link connector

MB991827

MB991824

MB991910

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 4. Check the spark plugs.
Refer to GROUP 16, Ignition System − On-vehicle Service −

Spark Plug Check

P.16-39

Q: Are there any abnormalities?

YES : Replace the spark plug. Then confirm that the

malfunction symptom is eliminated.

NO : Check the ignition coil (Refer to GROUP 16, Ignition

System − On-vehicle Service − Ignition Coil Check

P.16-37

). Then confirm that the malfunction symptom

is eliminated.

Inspection procedure 14: Hesitation, sag, stumble, poor acceleration or surge

COMMENT

• Defective ignition system, abnormal air/fuel ratio,

poor compression pressure, etc. are suspected.

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

• Malfunction of the fuel pump system.

• Malfunction of the ignition system.
• Poor compression.
• Improper operation of the PCV valve.
• Vacuum leak.
• Clogged air cleaner.
• Clogged exhaust system.
• Malfunction of the TC-SST system.
• Malfunction of the ECM.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan tool (M.U.T.-III Sub Assembly)

• MB991824: V.C.I.
• MB991827: USB Cable
• MB991910: Main Harness A

NOTE: To protect the TC-SST, the TC-SST-ECU outputs, into
the ECM, the request signal to reduce the engine torque
according to the operation condition. Based on the signal, the
ECM closes the throttle valve, retards the ignition or carries out
fuel cut. At that time, the engine output seems to temporarily
reduce, but there is no malfunction.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 1. Using scan tool MB991958, read the diagnostic
trouble code (DTC).

CAUTION

YES : Refer to Diagnostic Trouble Code Chart

P.13A-48

NO : Go to Step 2.

STEP 2. Using scan tool MB991958, read the diagnostic
trouble code (DTC).
NOTE: When the TC-SST has a malfunction, the TC-SST-ECU
might output the request signal of reducing the engine torque in
order to protect the TC-SST.
(1) Turn the ignition switch to the "ON" position.
(2) Read the TC-SST-DTC.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the TC-SST-DTC set?

YES : Refer to GROUP 22C, Diagnosis <TC-SST> −

Diagnostic Trouble Code Chart

P.22C-17

NO : Go to Step 3.

STEP 3. Using scan tool MB991958, check actuator test
item 1: injector.
(1) Turn the ignition switch to the "ON" position.
(2) Test Reference Table

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a. Item 1: Injector.

(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are thy operating properly?

YES : Go to Step 4.
NO : Repair or replace it. Then confirm that the malfunction

symptom is eliminated.

AC608435

Data link connector

MB991827

MB991824

MB991910

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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STEP 4. Check the ignition timing.
(1) Refer to GROUP 11A, On-vehicle Service − Ignition Timing

Check

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Q: Is the ignition timing normal?

YES : Go to Step 5.
NO : Check for installed conditions of the timing chain.

Then confirm that the malfunction symptom is
eliminated.

STEP 5. Using scan tool MB991958, check data list and
actuator test.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the data list. Refer to Data List

Reference Table

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a. Item 5: Intake Air Temperature Sensor.
b. Item 6: Engine Coolant Temperature Sensor.

c. Item 11: Accelerator Pedal Position Sensor (main).

d. Item 12: Accelerator Pedal Position Sensor (sub).
e. Item 13: Throttle Position Sensor (main).

f. Item 15: Throttle Position Sensor (sub).

(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are they operating properly?

YES : Go to Step 6.
NO : Repair or replace it. Then confirm that the malfunction

symptom is eliminated.

STEP 6. Check the fuel pressure.
Refer to Fuel Pressure Test

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Q: Is the fuel pressure normal?

YES : Go to Step 7.
NO : Repair or replace it. Then confirm that the malfunction

symptom is eliminated.

STEP 7. Check the spark plugs.
Refer to GROUP 16, Ignition System − On-vehicle Service −

Spark Plug Check And Cleaning

P.16-39

Q: Are there any abnormalities?

YES : Replace the spark plug. Then confirm that the

malfunction symptom is eliminated.

NO : Go to Step 8.

STEP 8. Check the ignition coil.
Refer to GROUP 16, Ignition System − On-vehicle Service −

Ignition Coil Check

P.16-37

Q: Are there any abnormalities?

YES : Replace the ignition coil. Then confirm that the

malfunction symptom is eliminated.

NO : Go to Step 9.

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