Symptom Chart - Engine Performance
| Symptom | 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 the appropriate Engine article for the procedure. Refer to Engine Controls - Symptom Charts (Except Diesel & Hybrid) . |
| Damaged charging system/ battery | REFER to: Charging System - 2.5L Duratec (125kW/170PS) . | |
| 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 the appropriate Engine article for the procedure. | |
| Fail-safe cooling invoked (if equipped) | Refer to Engine Controls - Symptom Charts (Except Diesel & Hybrid) . | |
| Poor idling | Vacuum leaks Inoperative or damaged EGR system |
Refer to the appropriate Engine article for the procedure. Refer to Engine Controls - Symptom Charts (Except Diesel & Hybrid) . |
| Inoperative or damaged ignition system | Refer to the appropriate Engine article for the procedure. | |
| Inoperative or damaged cooling system Inoperative or damaged fuel system |
Refer to the appropriate Engine article for the procedure. | |
| Fail-safe cooling invoked (if equipped) | Refer to Engine Controls - Symptom Charts (Except Diesel & Hybrid) . | |
| Incorrect valve clearance | ADJUST valve clearance. Refer to the appropriate Engine article 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 the appropriate Engine article for the procedure. |
| Fail-safe cooling invoked (if equipped) | Refer to Engine Controls - Symptom Charts (Except Diesel & Hybrid) . | |
| Burnt or sticking valve | INSTALL a new 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. |
| Damaged or collapsed air intake hoses and tubes | Tighten hoses clamps. INSPECT for damage and REPAIR as necessary. TEST the system for normal operation after the repair. | |
| Damaged exhaust or exhaust leaks at exhaust manifold. | INSPECT for leaks. Leaks can be detected audibility or visually, by a discoloration caused by escaping hot exhaust gases. REPAIR as necessary. 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. TEST the system for normal operation after the repair. | |
| 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 the appropriate Engine article for the procedure. TEST the system for normal operation after the repair. |
| Leaking oil cooler | INSPECT the oil cooler and seal for damage. INSTALL new components as necessary. Refer to the appropriate Engine article for the procedure. | |
| Coolant in oil | Leaking head gasket Damaged cylinder block Damaged cylinder head |
INSPECT the engine components. INSTALL new engine components as necessary. Refer to the appropriate Engine article 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 the appropriate Engine article for the procedure. Refer to Engine Controls - Symptom Charts (Except Diesel & Hybrid) . |
| Damaged exhaust or exhaust leaks at exhaust manifold | INSPECT for leaks. Leaks can be detected audibility or visually, by a discoloration caused by escaping hot exhaust gases. REPAIR as necessary. TEST the system for normal operation after the repair. | |
| Oil level too high | DRAIN oil to correct level. | |
| 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 the appropriate Engine article for the procedure. | |
| Fail-safe cooling invoked (if equipped) | Refer to Engine Controls - Symptom Charts (Except Diesel & 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 . | |
| Dragging brakes | REFER to: Brake System . | |
| Slipping transmission | Refer to the appropriate Automatic Transmission article for the procedure. | |
| Slipping clutch | Refer to the appropriate Manual Transmission article for the procedure. | |
| Incorrect valve clearance | ADJUST valve clearance. Refer to the appropriate Engine article 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. | |
| Engine emits excessive black smoke (black/blue/white) | Clogged Air Cleaner (ACL) element | INSTALL a new ACL element. TEST the system for normal operation after the repair. |
| Incorrect type or grade of oil | DRAIN and FILL with specified oil. | |
| Engine wear (piston rings, valve guides) | REPAIR as necessary. TEST the system for normal operation after the repair. | |
| Plugged crankcase ventilation system | Visually INSPECT the crankcase ventilation system. | |