Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSMITSUBISHI2004LANCER L4-2.4L SOHCREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSTESTING AND INSPECTIONSYMPTOM RELATED DIAGNOSTIC PROCEDURESINSPECTION PROCEDURE 14
2004 Mitsubishi Lancer L4-2.4L SOHC
Inspection Procedure 14
2004 Mitsubishi Lancer L4-2.4L SOHCSECTION Inspection Procedure 14
The engine stalls when decelerating
COMMENT
- The intake air volume may be insufficient due to a defective electronic control throttle valve system.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of the electronic control throttle valve system.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
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 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 connecting 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 the DTC set?
YES: Refer to Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions
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. Data List Reference Table & Normal Scan Data Values
a. Item 79: Throttle Position Sensor (main).
b. Item 14: Throttle Position Sensor (sub).
c. Item 78: Accelerator Pedal Position Sensor (main).
d. Item 77: Accelerator Pedal 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.
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.
NO: Check the following items, and repair, replace or clean the defective sections.
a. Check the ignition coil and spark plugs.
b. Check the EGR valve.
Then confirm that the malfunction symptom is eliminated.
COMMENT
- The intake air volume may be insufficient due to a defective electronic control throttle valve system.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of the electronic control throttle valve system.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
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 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 connecting 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 the DTC set?
YES: Refer to Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions
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. Data List Reference Table & Normal Scan Data Values
a. Item 79: Throttle Position Sensor (main).
b. Item 14: Throttle Position Sensor (sub).
c. Item 78: Accelerator Pedal Position Sensor (main).
d. Item 77: Accelerator Pedal 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.
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.
NO: Check the following items, and repair, replace or clean the defective sections.
a. Check the ignition coil and spark plugs.
b. Check the EGR valve.
Then confirm that the malfunction symptom is eliminated.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.