Engine Performance Diagnostic Table

WARNING: This page is about a different variant/trim than selected.

CONDITION	POSSIBLE CAUSE	CORRECTION
ENGINE WILL NOT START	1. Weak battery.	1. Test the battery. Charge or replace as necessary. Refer to BATTERY, DIAGNOSIS AND TESTING .
	2. Corroded or loose battery connections.	2. Clean and tighten the battery connections. Apply a coat of light mineral grease to the terminals. Refer to BATTERY SPECIFICATIONS .
	3. Faulty engine starting system.	3. Test the starting system. Refer to DIAGNOSIS AND TESTING .
	4. Faulty coil(s).	4. Test the ignition coil and replace as needed. Refer to DIAGNOSIS AND TESTING .
	5. Incorrect spark plug gap.	5. Check the spark plug gap. Refer to SPECIFICATIONS .
	6. Contamination in fuel system.	6. Clean the fuel system and replace the fuel filter. Refer to MODULE, FUEL PUMP, REMOVAL .
	7. Faulty fuel pump.	7. Test the fuel pump and replace as needed. Refer to DIAGNOSIS AND TESTING .
	8. Incorrect cam timing.	8. Verify cam timing. Refer to VALVE TIMING VERIFICATION .
	9. Faulty Camshaft Position (CMP) sensor.	9. Replace the Camshaft Position (CMP) sensor. Refer to SENSOR, CAMSHAFT POSITION, REMOVAL .
	10. Faulty Crankshaft Position (CKP) sensor.	10. Replace the Crankshaft Position (CKP) sensor. Refer to REMOVAL .
ENGINE STALLS OR IDLES ROUGH	1. Idle speed too low.	1. Check for Diagnostic Trouble Codes (DTC). Refer to STANDARD PROCEDURE .
	2. Incorrect fuel mixture.	2. Check for Diagnostic Trouble Codes (DTC). Refer to STANDARD PROCEDURE .
	3. Vacuum leak.	3. Inspect intake manifold, manifold gasket, and vacuum hoses.
	4. Faulty ignition coil(s).	4. Test and replace the ignition coil. Refer to REMOVAL .
	5. Faulty Crankshaft Position (CKP) sensor.	5. Replace the Crankshaft Position (CKP) sensor. Refer to REMOVAL .
	6. Incorrect cam timing.	6. Verify cam timing. Refer to VALVE TIMING VERIFICATION .
ENGINE LOSS OF POWER	1. Dirty or incorrectly gapped spark plugs.	1. Correct as necessary. Refer to REMOVAL .
	2. Contamination in fuel system.	2. Clean the fuel system and replace the fuel filter. Refer to MODULE, FUEL PUMP, REMOVAL .
	3. Faulty fuel pump.	3. Test and replace the fuel pump. Refer to MODULE, FUEL PUMP, REMOVAL .
	4. Leaking cylinder head gasket.	4. Replace the cylinder head gasket. Refer to REMOVAL .
	5. Low compression.	5. Determine the cause and repair as necessary. Refer to CYLINDER COMPRESSION TEST .
	6. Burned, warped, or pitted valves.	6. Replace valves as necessary. Refer to REMOVAL .
	7. Plugged or restricted exhaust system.	7. Perform the exhaust restriction test. Install new parts as necessary. Refer to EXCESSIVE EXHAUST SYSTEM NOISE .
	8. Faulty ignition coil(s).	8. Test and replace the ignition coil. Refer to REMOVAL .
	9. Incorrect valve timing.	9. Verify cam timing. Refer to VALVE TIMING VERIFICATION .
ENGINE MISSES ON ACCELERATION	1. Dirty or incorrectly gapped spark plugs.	1. Correct as necessary. Refer to REMOVAL .
	2. Contamination in fuel system.	2. Clean fuel system and replace the fuel filter. Refer to MODULE, FUEL PUMP, REMOVAL .
	3. Burned, warped, or pitted valves.	3. Replace valves as necessary. Refer to REMOVAL .
	4. Faulty ignition coil(s).	4. Test and replace the ignition coil. Refer to REMOVAL .
ENGINE MISSES AT HIGH SPEED	1. Dirty or incorrect spark plug gap.	1. Correct as necessary. Refer to REMOVAL .
	2. Faulty ignition coil(s).	2. Test and replace the ignition coil. Refer to REMOVAL .
	3. Contamination in fuel system.	3. Clean the fuel system and replace the fuel filter. Refer to MODULE, FUEL PUMP, REMOVAL .
	4. Dirty fuel injector(s).	4. Test and replace as necessary. Refer to DIAGNOSIS AND TESTING .