Engine Performance Diagnostic Table

WARNING: This page is about a different car, the 2012 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.

CONDITION	POSSIBLE CAUSE	CORRECTION
ENGINE WILL NOT START	1. Weak battery	1. Charge or replace as necessary.
	2. Corroded or loose battery connections.	2. Clean and tighten battery connections. Apply a coat of light mineral grease to the terminals.
	3. Faulty starter.	3. Refer to DIAGNOSIS AND TESTING .
	4. Faulty coil or control unit.	4. Refer to COIL, IGNITION, REMOVAL .
	5. Incorrect spark plug gap.	5. Refer to SPARK PLUG .
	6. Incorrect right bank cam timing.	6. Refer to VALVE TIMING .
	7. Dirt or water in fuel system.	7. Clean system and replace fuel filter.
	8. Faulty fuel pump, relay or wiring.	8. Repair or replace as necessary.
	9. Faulty cam or crank sensor	9. Refer to IGNITION SYSTEM - SERVICE INFORMATION article.
ENGINE STALLS OR ROUGH IDLE	1. Vacuum leak.	1. Inspect intake manifold and vacuum hoses, repair or replace as necessary.
	2. Faulty crank position sensor	2. Replace crank position sensor.
	3. Faulty coil.	3. Refer to COIL, IGNITION, REMOVAL .
	4. Incorrect cam timing.	4. Refer to Engine/Valve Timing - Standard Procedure .
ENGINE LOSS OF POWER	1. Dirty or incorrectly gapped spark plugs.	1. Refer to SPARK PLUG .
	2. Dirt or water in fuel system.	2. Clean system and replace fuel filter.
	3. Faulty fuel pump.	3. Refer to PUMP, FUEL .
	4. Blown cylinder head gasket.	4. Replace cylinder head gasket.
	5. Low compression.	5. Repair as necessary. Refer to CYLINDER COMBUSTION PRESSURE LEAKAGE .
	6. Burned, warped or pitted valves.	6. Replace as necessary.
	7. Plugged or restricted exhaust system.	7. Inspect and replace as necessary.
	8. Faulty coil.	8. Refer to COIL, IGNITION, REMOVAL .
	9. Incorrect cam timing.	9. Refer to VALVE TIMING .
ENGINE MISSES ON ACCELERATION	1. Spark plugs dirty or incorrectly gapped.	1. Refer to SPARK PLUG .
	2. Dirt in fuel system.	2. Clean fuel system.
	3. Burned, warped or pitted valves.	3. Replace as necessary.
	4. Faulty coil.	4. Refer to COIL, IGNITION, REMOVAL .
ENGINE MISSES AT HIGH SPEED	1. Spark plugs dirty or incorrectly gapped.	1. Refer to SPARK PLUG .
	2. Faulty coil.	2. Refer to COIL, IGNITION, REMOVAL .
	3. Dirt or water in fuel system.	3. Clean system and replace fuel filter.