Symptom Chart - Engine Performance

SYMPTOM CHART - ENGINE PERFORMANCE

Condition	Possible Sources	Action
Difficult starting	Damaged ignition system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Damaged fuel system	Refer to the appropriate appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Damaged starting system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Damaged charging system/battery	REFER to CHARGING SYSTEM article.
	Burnt valve	INSTALL a new valve.
	Worn piston	For 2.3L engines, INSTALL a new piston and piston pin. For 4.0L engines, INSTALL a new short block.
	Worn piston rings	For 2.3L engines, INSTALL new piston rings. For 4.0L engines, INSTALL a new short block.
	Worn cylinder	For 2.3L engines, INSTALL a new cylinder block. For 4.0L engines, INSTALL a new short block.
	Damaged head gasket	INSTALL a new head gasket.
	Damaged cooling system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
Poor idling	Vacuum leaks	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Malfunctioning or damaged ignition system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Malfunctioning or damaged fuel system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Damaged lash adjuster	INSTALL a new lash adjuster.
	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 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	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Malfunctioning or damaged ignition system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Malfunctioning or damaged air intake system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Damaged lash adjuster	INSTALL a new lash adjuster.
	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 2.3L engines, INSTALL new piston rings. For 4.0L engines, INSTALL a new short block.
	Worn piston ring groove	For 2.3L engines, INSTALL a new piston. For 4.0L engines, INSTALL a new short block.
	Worn piston or cylinder	For 2.3L engines, INSTALL a new cylinder block. For 4.0L engines, INSTALL a new short block.
Engine noise	Leaking exhaust system	REPAIR exhaust leakage.
	Incorrect drive belt tension	REFER to ACCESSORY DRIVE BELT article.
	Malfunctioning generator bearing	Refer to the appropriate Battery and Charging article for the procedure.
	Malfunctioning water pump bearing	REFER to ENGINE COOLING SYSTEM article.
	Malfunctioning or damaged cooling system	REFER to ENGINE COOLING SYSTEM article.
	Malfunctioning or damaged fuel system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	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	For 2.3L engines, INSTALL a new crankshaft main bearing. For 4.0L engines, INSTALL a new short block.
	Seized or heat damaged crankshaft main bearing	For 2.3L engines, INSTALL a new crankshaft main bearing. For 4.0L engines, INSTALL a new short block. CHECK the cylinder head distortion.
	Excessive crankshaft end play	For 2.3L engines, INSTALL a new thrust bearing or crankshaft. For 4.0L engines, INSTALL a new short block.
	Excessive connecting rod bearing clearance	For 2.3L engines, INSTALL a new connecting rod bearing or connecting rod. For 4.0L engines, INSTALL a new short block.
	Heat damaged connecting rod bearing	For 2.3L engines, INSTALL a new connecting rod bearing or connecting rod. For 4.0L engines, INSTALL a new short block.
	Damaged connecting rod bushing	For 2.3L engines, INSTALL a new connecting rod bushing. For 4.0L engines, INSTALL a new short block.
	Worn cylinder	For 2.3L engines, INSTALL new cylinder block. For 4.0L engines, INSTALL a new short block.
	Worn piston or piston pin	For 2.3L engines, INSTALL new piston or piston pin. For 4.0L engines, INSTALL a new short block.
	Damaged piston rings	For 2.3L engines, INSTALL new piston rings. For 4.0L engines, INSTALL a new short block.
	Bent connecting rod	For 2.3L engines, INSTALL a new connecting rod. For 4.0L engines, INSTALL a new short block.
	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 and stem.
Insufficient power	Malfunctioning or damaged ignition system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Malfunctioning or damaged fuel system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Malfunctioning or damaged air intake system	Refer to the appropriate Engine article for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS article.
	Damaged or plugged exhaust system	INSPECT exhaust system.
	Incorrect tire size	REFER to WHEELS & TIRES article.
	Dragging brakes	REFER to BRAKE SYSTEM - GENERAL INFORMATION article.
	Slipping transmission	Refer to the appropriate Automatic Transmission article for the procedure.
	Malfunctioning valve tappet or lash adjuster	INSTALL a new valve tappet or lash adjuster.
	Damaged valve tappet guide, valve tappet or lash adjuster guide	For 2.3L engines, INSTALL a new valve tappet guide or valve tappet. For 4.0L SOHC engines, INSTALL a new cylinder head.
	Compression leakage at valve seat	For 2.3L engines, REPAIR or INSTALL a new valve, valve seat or cylinder head. For 4.0L SOHC engines, INSTALL a new cylinder head.
	Seized valve stem	For 2.3L engines, INSTALL a new valve. For 4.0L SOHC engines, INSTALL a new cylinder head.
	Weak or broken valve spring	INSTALL a new valve spring.
	Worn or damaged cam	For 2.3L engines, INSTALL a new camshaft. For 4.0L SOHC engines, INSTALL a new cylinder head.
	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)	For 2.3L engines, INSTALL new piston rings. For 4.0L engines, INSTALL a new short block.
	Worn or damaged piston	For 2.3L engines, INSTALL a new piston or piston pin. For 4.0L engines, INSTALL a new short block.