NO.21 ENGINE NOISE [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5]

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21

ENGINE NOISE
DESCRIPTION
•  Engine noise from under bonnet.
POSSIBLE CAUSE
Buzzing sound is heard from exhaust pipe during cold engine start:
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.
•  Exhaust system installation condition
•  Intake system installation condition
Squeal, click or chirp noise:
•  Improper engine oil level
•  Loose installation of solenoid valves
•  Improper drive belt tension
•  Generator installation
•  Auto tensioner bearing malfunction
•  Splash shield or under cover loose (splash water to drive belt)
Thumping / rattling or creaking sound noise:
•  Improper drive belt tension
•  Loose parts
•  Loose fitting heater hoses vibrating the heater hose bracket protector
Hiss sound noise:
•  Vacuum leakage
•  Loose spark plug
•  Air leakage from the intake-air system
Rattle noise:
•  Loose parts
Rap or roar noise:
•  Dynamic damper loose
•  Exhaust system loose
•  Intake-air system loose
Other noise:
•  Electric variable valve timing actuator malfunction
•  Hydraulic variable valve timing actuator malfunction
•  Timing chain noise
•  Hydraulic lash adjuster (HLA) noise
Warning
The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before performing the fuel system services:
•  Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel.
•  Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injury or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete “BEFORE SERVICE PRECAUTION” and “AFTER SERVICE PRECAUTION” described in this manual. (See BEFORE SERVICE PRECAUTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) (See AFTER SERVICE PRECAUTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
Caution
•  Disconnecting/connecting the quick release connector without cleaning it may possibly cause damage to the fuel pipe and quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.

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 Step 2.
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.
Other noise is heard:
•  Go to Step 8.
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 9.
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 9.
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 9.
5
VERIFY IF THERE IS HISS 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 9.
6
VERIFY IF THERE IS RATTLE 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 9.
7
VERIFY IF THERE IS RAP OR ROAR 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 9.
8
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 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
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.
9
Verify the test results.
•  If normal, return to the diagnostic index to service any additional symptoms.
•  If a malfunction remains, inspect the related Service Information and perform the repair or diagnosis.
―  If the vehicle is repaired, troubleshooting is completed.
―  If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM.