Symptom Chart - Engine Performance

SYMPTOM CHART - ENGINE PERFORMANCE

Condition	Possible Sources	Action
Difficult starting	Inoperative or damaged ignition system Air or vacuum leak Inoperative or damaged fuel system Inoperative or damaged starting system	INSPECT the starting system for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS .
	Damaged charging system/battery	REFER to CHARGING SYSTEM .
	Low oil pressure	CARRY OUT the OIL PRESSURE TEST .
	Burnt valve	INSPECT the valve(s) and valve seat(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Worn piston	INSPECT the piston(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Worn piston rings	INSPECT the piston ring(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Worn cylinder	INSPECT the cylinder block for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Damaged head gasket	INSPECT the cylinder head gasket(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Damaged cooling system	INSPECT the cooling system for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
Poor idling	Vacuum leaks Malfunctioning or damaged ignition system Malfunctioning or damaged fuel system	Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure. REFER to the Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool.
	Damaged hydraulic lash adjuster	INSPECT the hydraulic lash adjuster(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Incorrect valve-to-seat contact	INSPECT the valve(s) and cylinder head(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Damaged head gasket	INSPECT the cylinder head gasket(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Low oil pressure	CARRY OUT the OIL PRESSURE TEST .
	Worn or damaged engine support bracket(s)	INSPECT the engine support bracket(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Worn or damaged engine support insulator(s)	INSPECT the engine support insulator(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Worn or damaged transmission insulator and retainer	INSPECT the transmission insulator and retainer for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
Abnormal combustion	Inoperative or damaged fuel system Air or vacuum leaks EGR system fault Inoperative or damaged cooling system (if equipped, fail-safe cooling invoked) Inoperative or damaged ignition system	INSPECT each system for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS .
	Malfunctioning or damaged air intake system	INSPECT the air intake system for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Damaged hydraulic lash adjuster(s)	INSPECT the hydraulic lash adjuster(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Burnt or sticking valve	INSPECT the valve(s) and valve seat(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Weak or broken valve spring	INSPECT the valve spring(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Carbon accumulation in combustion chamber	ELIMINATE carbon buildup.
Excessive oil consumption	Leaking oil	REPAIR oil leakage.
	Malfunctioning PCV system	INSPECT the PCV system for damage. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure. REFER to the INTRODUCTION - GASOLINE MODELS .
	Worn valve stem seal	INSPECT the valve(s) and valve stem seal(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Worn valve stem or valve guide	INSPECT the valve(s) and cylinder head(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Sticking piston rings	INSPECT the piston(s) and cylinder block for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Worn piston ring groove	INSPECT the piston(s) for damage. INSTALL new components as necessary. Refer to theENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Worn piston or cylinder	INSPECT the piston(s) and cylinder block for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
Insufficient power	Inoperative or damaged ignition system Air intake system blockage Lubrication system blockage Inoperative or damaged fuel system	REFER to the INTRODUCTION - GASOLINE MODELS .
	Oil level too high	DRAIN oil to correct level.
	Incorrect engine oil	INSTALL correct specification engine oil.
	Low oil pressure	CARRY OUT the OIL PRESSURE TEST .
	Excessive accessory drive belt loading	INSPECT the accessory drive system for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Inoperative or damaged cooling system (if equipped, fail-safe cooling invoked)	INSPECT the cooling system for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Damaged or plugged exhaust system	INSPECT the exhaust system for flow and damage. INSTALL new components as necessary. REFER to ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V)EXHAUST SYSTEM .
	Incorrect tire size	REFER to SUSPENSION SYSTEM - GENERAL INFORMATION .
	Dragging brakes	REFER to BRAKE SYSTEM - GENERAL INFORMATION .
	Slipping transmission	Refer to the AUTOMATIC TRANSAXLE/TRANSMISSION - 5R55S for the procedure.
	Malfunctioning hydraulic lash adjuster	INSPECT the hydraulic lash adjuster for wear or damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Compression leakage at valve seat	INSPECT the valve, valve seat and cylinder head for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Seized valve stem	INSPECT the valve for wear or damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Weak or broken valve spring	INSPECT the valve spring. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Worn or damaged camshaft	INSPECT the camshaft for wear or damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Damaged head gasket(s)	INSPECT the cylinder head gasket(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Cracked or distorted cylinder head(s)	INSPECT the cylinder head(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Damaged, worn or sticking piston ring(s)	INSPECT the piston ring(s) for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Worn or damaged piston	INSPECT the piston for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
Oil in coolant	Leaking head gasket	INSTALL a new head gasket. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Leaking oil cooler	INSPECT the oil filter adapter and seal for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Leaking oil filter adapter	INSPECT the oil filter adapter and gasket for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Damaged cylinder head	INSPECT the engine components for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
	Damaged cylinder block	INSPECT the engine components for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.
Coolant in oil	Leaking head gasket Leaking oil cooler Leaking oil filter adapter Damaged cylinder head Damaged cylinder block	INSPECT the engine components for damage. INSTALL new components as necessary. Refer to the ENGINE - 4.0L SOHC , ENGINE - 4.6L (3V) , and ENGINE - 5.4L (4V) for the procedure.