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 |
Refer to the appropriate Engine article for the procedure. REFER to the Engine Controls - Introduction (Except Diesel & Hybrid) . |
| Damaged charging system/battery | REFER to Charging System . | |
| Burnt valve | INSTALL a new valve in the 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 Cooling . | |
| Fail-safe cooling invoked (if equipped) | REFER to the Engine Controls - Introduction (Except Diesel & Hybrid) . | |
| Poor idling | Vacuum leaks | Refer to the appropriate Engine article for the procedure. REFER to the Engine Controls - Introduction (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 the Engine Controls - Introduction (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 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 the Engine Controls - Introduction (Except Diesel & Hybrid) . | |
| Burnt or sticking valve | INSTALL a new valve in the cylinder head. 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. |
| Blocked or restricted turbocharger oil drain pipe | Inspect the turbocharger oil drain pipe. REPAIR as necessary. TEST the system for normal operation after the repair. | |
| Damaged or collapsed air intake hoses and tubes | Tighten the hose clamps. Inspect for damage and REPAIR as necessary. TEST the system for normal operation after the repair. | |
| Damaged exhaust or exhaust leaks at the turbocharger housing or exhaust manifold | INSPECT for leaks. Leaks can usually be detected audibly or visually, by discoloration caused by escaping hot exhaust gases. REPAIR as necessary. TEST the system for normal operation after the repair. | |
| Turbocharger oil seals leaking | Refer to the Turbocharger Internal Oil Leak Test. | |
| 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 the appropriate Engine article for the procedure. TEST the system for normal operation after the repair. |
| Coolant in oil | Leaking head gasket Damaged cylinder block Damaged cylinder head Damaged coolant pump/seal/gasket |
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 the Engine Controls - Introduction (Except Diesel & Hybrid) . |
| Turbocharger turbine or compressor wheel damage | INSPECT the turbocharger. | |
| Damaged exhaust or exhaust leaks at the turbocharger housing or exhaust manifold | INSPECT for leaks. Leaks can usually be detected audibly or visually, by a discoloration caused by escaping hot exhaust gases. REPAIR as necessary. TEST the system for normal operation after the repair. | |
| Malfunctioning turbocharger bypass valve | REFER to the Engine Controls - Introduction (Except Diesel & 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 the appropriate Engine article for the procedure. | |
| Fail-safe cooling invoked (if equipped) | REFER to the Engine Controls - Introduction (Except Diesel & Hybrid) . | |
| 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 the appropriate Automatic 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 smoke (black/blue/white) | Clogged Air Cleaner (ACL) element | INSTALL a new ACL element. REFER to Intake Air Distribution and Filtering . TEST the system for normal operation after the repair. |
| Incorrect type or grade of oil | DRAIN and FILL with the specified oil. | |
| Blocked or restricted turbocharger oil drain pipe | Inspect the turbocharger oil drain pipe. REPAIR as necessary. TEST the system for normal operation after the repair. | |
| Damaged/restricted or leaking turbocharger intake tube assembly | REPAIR or INSTALL a new tube as necessary. TEST the system for normal operation after the repair. | |
| Engine wear (piston ring, valve guides) | REPAIR as necessary. TEST the system for normal operation after the repair. | |
| Plugged crankcase ventilation system | Visually INSPECT the crankcase ventilation system. | |
| Turbocharger oil seals leaking | REFER to the Turbocharger Internal Oil Leak Test. | |