Inspection Procedure 16
Inspection procedure 16: KnockingCOMMENT
- In cases such as the above, the cause is probably that the detonation control is defective or the heat value of the spark plug is inappropriate.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Defective knock sensor.
- Incorrect heat value of the spark plug.
- Poor compression.
- 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
STEP 1. Using the 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 any DTC set?
YES : Refer to Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions
NO : Go to Step 2.
STEP 2. Using scan tool MB991958, 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. Datal List Reference Table
a. Item 32: Knock retard.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES : Go to Step 3.
NO : Refer to DTC P0327 - Knock Sensor Circuit Low Input, P0327 DTC P0328 - Knock Sensor Circuit High Input. P0328
STEP 3. Check the spark plugs.
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 compression pressure.
Q: Is the compression pressure normal?
YES : Check the following items, and repair or replace the defective items.
a. Check if fuel is contaminated.
b. Check if the foreign materials (water, kerosene, etc.) got into fuel.
c. Check the octane level of the fuel.
Then confirm that the malfunction symptom is eliminated.
NO : Repair it. Then confirm that the malfunction symptom is eliminated.