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Home >> Mazda >> 2021 >> CX-9 Signature >> Repair and Diagnosis >> Engine Performance >> System >> Symptom Troubleshooting - Engine >> No. 21 Engine Noise >> Diagnostic Procedure

Diagnostic Procedure

NO. 21 ENGINE NOISE (SKYACTIV-G 2.5T) DIAGNOSTIC PROCEDURE

STEP INSPECTION RESULTS ACTION
1 VERIFY SYMPTOM
  • Verify the occurring sound.
- Buzzing sound is heard from exhaust pipe during cold engine start:
  • Go to the next step.

    Squeal, click, or chirp sound is heard:

  • Go to Step 3.

    Thumping/rattling or creaking sound is heard:

  • Go to Step 4.

    Hissing sound is heard:

  • Go to Step 5.

    Clattering sound is heard:

  • Go to Step 6.

    Lightly tapping or rumbling sound is heard:

  • Go to Step 7.

    Excessive noise from turbocharger:

  • Go to Step 8.

    Other noise is heard:

  • Go to Step 10.
2 BUZZING SOUND IS HEARD FROM EXHAUST PIPE DURING COLD ENGINE START
  • Verify the sound from the exhaust pipe during a cold engine start.
  • Does the sound disappear after approx. 30 s have elapsed?
Yes
NOTE:
  • During a cold engine start, sound occurs for up to approx. 30 s with fast idle up for a drive-by-wire control and the warm-up promotion spark retard correction for ignition timing control.
Go to Step 9 because the operation is normal.
No Inspect the following:
  • Exhaust system installation condition
  • Intake system installation condition
    • If there is any malfunction:
      • Repair or replace the malfunctioning part according to the inspection results.
    • If there is no malfunction:
      • Go to Step 12.
3 VERIFY IF THERE IS SQUEAL, CLICK, OR CHIRP SOUND
  • Inspect the following:
    • Engine oil level
    • Solenoid valves installation
    • Drive belt tension
    • Generator installation
    • Auto tensioner bearing damaged
      • Splash shield or under cover loose
  • Is there any malfunction?
Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to Step 12.
4 VERIFY IF THERE IS THUMPING/RATTLING OR CREAKING SOUND
  • Inspect the following:
    • Drive belt tension
    • Loose parts in engine compartment
      • Loose fitting heater hoses vibrating the heater hose bracket protector
  • Is there any malfunction?
Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to Step 12.
5 VERIFY IF THERE IS HISSING SOUND
  • Inspect the following:
    • Vacuum leakage
    • Spark plug loose
      • Intake-air system leakage
  • Is there any malfunction?
Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to Step 12.
6 VERIFY IF THERE IS CLATTERING SOUND
  • Inspect the location of rattle for loose parts.
  • Is there any malfunction?
Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to Step 12.
7 VERIFY IF THERE IS LIGHTLY TAPPING OR RUMBLING SOUND
  • Inspect the following:
    • Exhaust system installation condition
      • Intake system installation condition
  • Is there any malfunction?
Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to Step 12.
8 VISUALLY INSPECT THE TURBOCHARGER
  • Remove the parts necessary to inspect the turbocharger without removing the turbocharger.
  • Inspect if the turbocharger compressor wheel is bent, damaged, or interfering with housing on vehicle.
  • Is there any malfunction?
Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to next step.
9 VISUALLY INSPECT THE TURBINE HOUSING
  • Visually inspect the turbine housing.
  • Is there any carbon built-up or foreign material on the turbine housing?
Yes Clean built-up carbon or remove foreign materials.
No Replace the intake air system.
(See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [SKYACTIV-G 2.5T] .)
10 VERIFY IF THERE IS KNOCK SOUND
  • Is knocking noise present?
Yes Perform the symptom troubleshooting "NO. 13 KNOCKING/PINGING-ACCELERATION/CRUISE".
(See NO. 13 KNOCKING/PINGING-ACCELERATION/CRUISE [SKYACTIV-G 2.5T] .)
No If noise comes from engine internal:
  • Inspect the following:
    • Timing chain
    • Hydraulic lash adjuster (HLA) noise
    • Electric variable valve timing actuator
    • Hydraulic variable valve timing actuator
      • Engine compression
  • Repair or replace the malfunctioning part according to the inspection results.
11 Verify the test results.
  • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [SKYACTIV-G 2.5T] .)
  • If the malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.
    • If the vehicle is repaired, troubleshooting is completed.
      • If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.