Symptom Chart

Condition	Possible Sources	Action
Difficult starting	Damaged ignition system Damaged fuel system Damaged starting system	Refer to the appropriate procedures. REFER to the Introduction - Gasoline Engines .
	Damaged charging system/battery	REFER to CHARGING SYSTEM - GENERAL INFORMATION .
	Burnt valve	INSTALL a new valve.
	Worn piston	For 4.0L engines, INSTALL a new piston and connecting rod assembly. For 4.6L and 5.4L engines, INSTALL a new piston.
	Worn piston rings	INSTALL new piston rings.
	Worn cylinder	REPAIR or INSTALL a new cylinder block.
	Damaged head gasket	INSTALL a new head gasket.
	Damaged cooling system	Refer to the appropriate procedures. REFER to the Introduction - Gasoline Engines .
Poor idling	Vacuum leaks Malfunctioning or damaged ignition system Malfunctioning or damaged fuel system	Refer to the appropriate procedures. REFER to the Introduction - Gasoline Engines .
	Damaged valve tappet or lash adjuster	INSTALL a new valve tappet or lash adjuster.
	Damaged valve tappet guide or lash adjuster	INSTALL a new valve tappet guide or valve tappet.
	Incorrect valve-to-valve seat contact	REPAIR or INSTALL a new valve or valve seat.
	Damaged head gasket	INSTALL a new head gasket.
	Worn or damaged engine support brackets	INSTALL a new engine support brackets.
	Worn or damaged engine support insulators	INSTALL a new engine support insulator.
	Worn or damaged transmission insulator and retainer	INSTALL a new transmission insulator and retainer.
Abnormal combustion	Malfunctioning or damaged fuel system Malfunctioning or damaged ignition system Malfunctioning or damaged air intake system	Refer to the appropriate procedures. REFER to the Introduction - Gasoline Engines .
	Damaged valve tappet or lash adjuster	INSTALL a new valve tappet or lash adjuster.
	Damaged valve tappet guide or valve tappet	INSTALL a new valve tappet guide or valve tappet.
	Burnt or sticking valve	REPAIR or INSTALL a new valve.
	Weak or broken valve spring	INSTALL a new valve spring.
	Carbon accumulation in combustion chamber	ELIMINATE carbon buildup.
Excessive oil consumption	Leaking oil	REPAIR oil leakage.
	Malfunctioning PCV system	REPAIR or INSTALL new necessary components.
	Worn valve stem seal	INSTALL a new valve stem seal.
	Worn valve stem or valve guide	INSTALL a new valve and valve guide.
	Sticking piston rings	For 4.0L engines, INSTALL a new piston and connecting rod assembly. For 4.6L and 5.4L engines, REPAIR or INSTALL new piston rings.
	Worn piston ring groove	For 4.0L engine, INSTALL a new piston and connecting rod assembly. For 4.6L and 5.4L engines, INSTALL a new piston and piston pin.
	Worn piston or cylinder	REPAIR or INSTALL a new piston or cylinder block.
Engine noise	Leaking exhaust system	REPAIR exhaust leakage.
	Incorrect drive belt tension	REFER to ACCESSORY DRIVE .
	Malfunctioning generator bearing	Refer to BATTERY, MOUNTING AND CABLES .
	Malfunctioning coolant pump bearing Malfunctioning or damaged cooling system	REFER to ENGINE COOLING .
	Malfunctioning or damaged fuel system	Refer to the appropriate procedures. REFER to the Introduction - Gasoline Engines .
	Loose timing chain/belt	ADJUST or INSTALL a new timing chain/belt.
	Damaged timing chain tensioner	INSTALL a new timing chain tensioner.
	Excessive main bearing clearance	CAUTION: Remove the cylinder heads before removing the crankshaft. Failure to do so can result in engine damage. ADJUST clearance or INSTALL new crankshaft main bearings.
	Seized or heat-damaged crankshaft main bearing	INSTALL new crankshaft main bearings.
	Excessive crankshaft end play	INSTALL a new thrust bearing or crankshaft.
	Excessive connecting rod bearing clearance	INSTALL new connecting rod bearings or connecting rods.
	Heat damaged connecting rod bearing Damaged connecting rod bushing	INSTALL new connecting rod bearings.
	Worn cylinder	REPAIR or INSTALL a new cylinder block.
	Worn piston or piston pin	INSTALL a new piston or piston pin.
	Damaged piston rings	INSTALL new piston rings.
	Bent connecting rod	INSTALL a new connecting rod.
	Malfunctioning valve tappet or lash adjuster	INSTALL a new valve tappet or lash adjuster.
	Excessive valve tappet or lash adjuster clearance	ADJUST clearance or INSTALL a new valve tappet guide or valve tappet.
	Broken valve spring	INSTALL a new valve spring.
	Excessive valve guide clearance	ADJUST clearance or INSTALL a new valve guide or valve.
Insufficient power	Malfunctioning or damaged ignition system Electronic throttle control (ETC) system concerns Malfunctioning or damaged fuel system Malfunctioning or damaged air intake system	Refer to the appropriate procedures. REFER to the Introduction - Gasoline Engines .
	Damaged or plugged exhaust system	INSPECT exhaust system.
	Incorrect tire size	REFER to SUSPENSION SYSTEM - GENERAL INFORMATION .
	Dragging brakes	REFER to BRAKE SYSTEM - GENERAL INFORMATION .
	Slipping transmission	Refer to AUTOMATIC TRANSAXLE/TRANSMISSION .
	Malfunctioning valve tappet or lash adjuster	INSTALL a new valve tappet or lash adjuster.
	Damaged valve tappet guide or valve tappet	INSTALL a new valve tappet guide or valve tappet.
	Compression leakage at valve seat	REPAIR or INSTALL a new valve, valve seat or cylinder head.
	Seized valve stem	INSTALL a new valve.
	Weak or broken valve spring	INSTALL a new valve spring.
	Worn or damaged camshaft	INSTALL a new camshaft.
	Damaged head gasket	INSTALL a new head gasket.
	Cracked or distorted cylinder head	INSTALL a new cylinder head.
	Damaged, worn or sticking piston ring(s)	REPAIR or INSTALL a new piston ring(s).
	Worn or damaged piston	INSTALL a new piston and piston pin.