Symptom Table - Engine Performance

WARNING: This page is about a different car, the 2010 Mercury Milan, 2010 Lincoln MKZ, and 2010 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

SYMPTOM TABLE - 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	Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure. REFER to INTRODUCTION - GASOLINE MODELS and/or INTRODUCTION -- HYBRID .
-	Damaged charging system/battery	REFER to CHARGING SYSTEM .
-	Burnt valve	INSTALL a new cylinder head. TEST the system for normal operation after the repair.
-	Worn piston	INSTALL a new piston. TEST the system for normal operation after the repair.
-	Worn piston rings	INSTALL new piston rings. TEST the system for normal operation after the repair.
-	Worn cylinder	INSTALL a new cylinder block. TEST the system for normal operation after the repair.
-	Damaged head gasket	INSTALL a new cylinder head gasket. TEST the system for normal operation after the repair.
-	Inoperative or damaged cooling system	Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure.
-	Fail-safe cooling invoked (if equipped)	REFER to the INTRODUCTION - GASOLINE MODELS and/or INTRODUCTION -- HYBRID .
Poor idling	Vacuum leaks Inoperative or damaged EGR system	Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure. REFER to INTRODUCTION - GASOLINE MODELS and/or INTRODUCTION -- HYBRID .
-	Inoperative or damaged ignition system	Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure.
-	Inoperative or damaged cooling system	Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure.
-	Inoperative or damaged fuel system	-
-	Fail-safe cooling invoked (if equipped)	REFER to the INTRODUCTION - GASOLINE MODELS and/or INTRODUCTION -- HYBRID .
-	Incorrect valve clearance	ADJUST valve clearance. Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure. TEST the system for normal operation after the repair.
-	Incorrect valve-to-valve seat contact	INSTALL a new cylinder head. TEST the system for normal operation after the repair.
-	Damaged head gasket	INSTALL a new cylinder head gasket. TEST the system for normal operation after the repair.
Engine runs rough	Inoperative or damaged fuel system Air or vacuum leaks EGR system fault Inoperative or damaged cooling system Inoperative or damaged ignition system	Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure.
-	Fail-safe cooling invoked (if equipped)	REFER to INTRODUCTION - GASOLINE MODELS and/or INTRODUCTION - HYBRID .
-	Burnt or sticking valve	INSTALL a new cylinder valve. TEST the system for normal operation after the repair.
-	Weak or broken valve spring	INSTALL a new valve spring. TEST the system for normal operation after the repair.
-	Carbon accumulation in combustion chamber	ELIMINATE carbon buildup. TEST the system for normal operation after the repair.
Excessive oil consumption	Leaking oil	REPAIR oil leakage. TEST the system for normal operation after the repair.
-	Inoperative PCV system	REPAIR or INSTALL new components as necessary. TEST the system for normal operation after the repair.
-	Incorrect oil	CHANGE oil to correct specification.
-	Worn valve stem seal	INSTALL a new valve stem seal. TEST the system for normal operation after the repair.
-	Worn valve stem or valve guide	INSTALL a new cylinder head. TEST the system for normal operation after the repair.
-	Sticking piston rings	INSTALL new piston rings. TEST the system for normal operation after the repair.
-	Worn piston ring groove	INSTALL a new piston and piston pin. TEST the system for normal operation after the repair.
-	Worn piston or cylinder	INSTALL a new piston or cylinder block. TEST the system for normal operation after the repair.
Oil in coolant	Leaking head gasket Damaged cylinder block Damaged cylinder head	INSPECT the engine components. INSTALL new engine components as necessary. Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure. TEST the system for normal operation after the repair.
Coolant in oil	Leaking head gasket Damaged cylinder block Damaged cylinder head	INSPECT the engine components. INSTALL new engine components as necessary. Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure. TEST the system for normal operation after the repair.
Insufficient power	Inoperative or damaged ignition system Air intake system blockage Lubrication system blockage Inoperative or damaged fuel system	Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure. REFER to INTRODUCTION - GASOLINE MODELS and/or INTRODUCTION -- HYBRID .
-	Oil level too high	DRAIN oil to correct level. TEST the system for normal operation after the repair.
-	Incorrect engine oil	INSTALL correct specification engine oil. TEST the system for normal operation after the repair.
-	Excessive accessory drive belt loading Inoperative or damaged cooling system	Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure.
-	Fail-safe cooling invoked (if equipped)	REFER to INTRODUCTION - GASOLINE MODELS and/or INTRODUCTION -- HYBRID .
-	Damaged or plugged exhaust system	INSPECT exhaust system. TEST the system for normal operation after the repair.
-	Incorrect tire size	REFER to SUSPENSION SYSTEM - GENERAL INFORMATION .
-	Dragging brakes	REFER to BRAKE SYSTEM - GENERAL INFORMATION .
-	Slipping transmission	Refer to DIAGNOSIS AND TESTING , AUTOMATIC TRANSAXLE/TRANSMISSION - AISIN AW21 and AUTOMATIC TRANSAXLE/TRANSMISSION - ELECTRONICALLY CONTROLLED CONTINUOUSLY VARIABLE TRANSMISSION (ECVT) for the procedure.
-	Incorrect valve clearance	ADJUST valve clearance. Refer to ENGINE (2.5L), ENGINE (Hybrid), ENGINE (3.0L) and ENGINE (3.5L) for the procedure. TEST the system for normal operation after the repair.
-	Worn or damaged valve tappet	INSTALL a new valve tappet. TEST the system for normal operation after the repair.
-	Damaged valve guide Compression leakage at valve seat Seized valve stem	INSTALL a new cylinder head assembly. TEST the system for normal operation after the repair.
-	Weak or broken valve spring	INSTALL a new valve spring. TEST the system for normal operation after the repair.
-	Worn or damaged cam	INSTALL a new camshaft. TEST the system for normal operation after the repair.
-	Damaged head gasket	INSTALL a new head gasket. TEST the system for normal operation after the repair.
-	Cracked or distorted cylinder head	INSTALL a new cylinder head assembly. TEST the system for normal operation after the repair.
-	Damaged, worn or sticking piston ring(s)	INSTALL a new piston ring(s). TEST the system for normal operation after the repair.
-	Worn or damaged piston	INSTALL a new piston and piston pin. TEST the system for normal operation after the repair.