Mitsubishi Lancer Evolution X. Manual - part 418

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-737

STEP 4. Inspection of throttle body (throttle valve area) for 
dirtiness.
Q: Is the throttle valve area dirty?

YES : Refer to On-vehicle Service − Throttle Body (Throttle 

Valve Area) Cleaning 

P.13A-865

.

NO :  Go to Step 5.

STEP 5. Check the fuel pressure.
Refer to Fuel Pressure Test 

P.13A-865

.

Q: Is the fuel pressure normal?

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

symptom is eliminated.

STEP 6. Check the ignition timing.
Refer to GROUP 11A, On-vehicle Service − Ignition Timing 

Check 

P.11A-10

.

Q: Is the ignition timing normal?

YES : Go to Step 7.
NO :  Check for installed conditions of the timing chain. 

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.

STEP 9. Check the compression pressure.
Refer to GROUP 11A, On-vehicle Service − Compression Pres-

sure Check 

P.11A-15

.

Q: Is the compression pressure normal?

YES : Go to Step 10.
NO :  Repair it. Then confirm that the malfunction symptom 

is eliminated.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 10. Check the positive crankcase ventilation system.
Refer to GROUP 17, Emission Control − Positive Crankcase 

Ventilation System − Positive Crankcase Ventilation System 

Check 

P.17-72

.

Q: Is the positive crankcase ventilation system?

YES : Go to Step 11.
NO :  Repair it. Then confirm that the malfunction symptom 

is eliminated.

STEP 11. Engine stall reproduction test.
Q: Is it easy to reproduce the engine stall?

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

defective items.

a. Vacuum leak.
b. Check if fuel is contaminated.

c. Check if the injectors are clogged.

d. Check if the foreign materials (water, 

kerosene, etc.) got into fuel.

Then confirm that the malfunction symptom is 

eliminated.

NO :  Check if the following signals change suddenly by 

wiggling the circuit harness and connectors.

a. Crankshaft position sensor signal.
b. Mass airflow sensor signal.

c. Injector drive signal.

d. Primary and secondary ignition signal.
e. Fuel pump drive signal.

f. ECM power supply voltage.

Then confirm that the malfunction symptom is 

eliminated.

Inspection procedure 12: The engine stalls accelerating (pass out)

.

COMMENT

• In case such as the above, the cause is probably 

misfiring due to a weak spark, or an inappropriate 
air/fuel mixture when the accelerator pedal is 
depressed.

.

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

• Malfunction of the ignition system.
• Malfunction of the evaporative emission control 

system.

• Improper operation of the PCV valve.
• Vacuum leak.
• 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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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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. Using scan tool MB991958, check actuator test.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following item in the actuator test. Refer to 

Actuator Test Reference Table 

P.13A-840

.

a. Item 10: Evaporative Emission Purge Solenoid.

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

YES : Go to Step 3.
NO :  Repair or replace it. Then confirm that the malfunction 

symptom is eliminated.

STEP 3. 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 4.

STEP 4. 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 5.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 5. Check the positive crankcase ventilation system.
Refer to GROUP 17, Emission Control − Positive Crankcase 

Ventilation System − Positive Crankcase Ventilation System 

Check 

P.17-72

.

Q: Is the positive crankcase ventilation system?

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

defective items.

a. Vacuum leak.

Then confirm that the malfunction symptom is 

eliminated.

NO :  Repair it. Then confirm that the malfunction symptom 

is eliminated.

Inspection procedure 13: The engine stalls decelerating

.

COMMENT

• The abnormal air/fuel ratio or other similar 

defects can possibly be caused by the insufficient 
intake air volume.

.

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

• Malfunction of the ignition system.
• Dirtiness around throttle valve.
• 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