13C-KNOCKING

Inspection procedure 16: Knocking

COMMENT

Incases 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.
ECM failed.

DIAGNOSIS

Required Special Tool:

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

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

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 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.

Is any DTC set?

Refer to, Diagnostic Trouble Code Chart

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 item in the data list. Refer to Data List Reference Table

Item 32: Knock Retard

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

Is the sensor operating properly?

Go to Step 3

Refer to, DTC P0327 - Knock Sensor Circuit Low

, DTC P0328 - Knock Sensor Circuit High

STEP 3. Check the spark plugs.

Refer to GROUP 16, Ignition System - On-vehicle Service - Spark Plug Check and Cleaning

Are there any abnormalities?

Replace the spark plug. Then confirm that the malfunction symptom is eliminated.

Go to Step 4

STEP 4. Check the compression pressure.

Refer to GROUP 11C, On-vehicle Service - Compression Pressure Check

Is the compression pressure normal?

Check the following items, and repair or replace the defective items.

Check if fuel is contaminated.
Check if the foreign materials (water, diesel fuel, etc.) got into fuel.

Then confirm that the malfunction symptom is eliminated.

Repair it. Then confirm that the malfunction symptom is eliminated.