NO.21 ENGINE NOISE [LF, L3]


21	ENGINE NOISE
DESCRIPTION	Engine noise from under the hood
POSSIBLE CAUSE	Squeal, click or chirp noise: • Improper engine oil level • Improper drive belt tension Rattle sound noise: • Loose parts Hiss sound noise: • Vacuum leakage • Loose spark plug • Air leakage from the intake-air system • Improper variable air duct (VAD) control system operation (L3 Engine Models) Rumble or grind noise: • Improper drive belt tension Rap or roar sound noise: • Exhaust system looseness Other noise: • Camshaft friction gear noise or MLA noise • Timing chain noise


STEP	INSPECTION	RESULTS	ACTION
1	Is a squeal, click or chirp sound present?	Yes	Inspect the engine oil level or drive belts.
1	Is a squeal, click or chirp sound present?	No	Go to the next step.
2	Is a rumble or grind sound present?	Yes	Inspect the drive belts.
2	Is a rumble or grind sound present?	No	Go to the next step.
3	Is a rattle sound present?	Yes	Inspect the location of the rattle for loose parts.
3	Is a rattle sound present?	No	Go to the next step.
4	Is a hiss sound present?	Yes	Inspect for the following: • Vacuum leakage • Spark plug looseness • Intake-air system leakage • Variable air duct (VAD) control system operation (L3 Engine Models) (See Variable Air Duct (VAD) Control System Operation Inspection (L3 Engine Models).)
4	Is a hiss sound present?	No	Go to the next step.
5	Is a rap or roar sound present?	Yes	Inspect the exhaust system for loose parts.
5	Is a rap or roar sound present?	No	Go to the next step.
6	Is a knock sound present?	Yes	Go to the symptom troubleshooting "No.11 Knocking/pinging".
6	Is a knock sound present?	No	If the noise comes from the inside of the engine, inspect for gear friction, timing chain or, MLA noise.
7	Verify the test results. • If normal, return to the diagnostic index to service any additional symptoms. • If the malfunction remains, replace the PCM.