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Engine Performance Diagnostic Table

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 TECHNICAL SPECIFICATIONS .
3. Faulty engine starting system. 3. Test the starting system. Refer to DIAGNOSIS AND TESTING .
4. Faulty coil(s) or control unit. 4. Test the ignition coil and replace as needed. Refer to DIAGNOSIS AND TESTING .
5. Incorrect spark plug gap. 5. Set the spark plug gap. Refer to TECHNICAL SPECIFICATIONS .
6. Contamination in fuel system. 6. Clean the fuel system and replace the fuel filter. Refer to MODULE, FUEL PUMP, REMOVAL AND INSTALLATION .
7. Incorrect engine oil level and oil quality. 7. The engine starting should not be effected if the oil level shows anywhere on the dipstick. If the oil level is off the dipstick, the oil level could be contributing to the startablity issue.
If the oil quality is questionable, change the oil and filter. Refer to FILTER, ENGINE OIL, REMOVAL AND INSTALLATION .
8. Insufficient quantity of engine oil in the Variable Valve Actuation Assembly (VVAA) due to:
  • Long term storage
  • Engine not started within the last 30 days
  • Replacement of the VVAA (MultiAir module)
 8. Operate the starter to fill the VVAA with oil and enable its operation:
  • Hold the Accelerator Pedal wide open during cranking to cut off fuel and avoid flooding.
  • After the first few cycles, release the Accelerator Pedal to allow fuel for engine starting.

CAUTION: Do not exceed 20 seconds of starter operation and allow 60 seconds cool-down between cycles. 
9. Faulty fuel pump. 9. Test the fuel pump and replace as needed. Refer to DIAGNOSIS AND TESTING .
10. Incorrect cam timing. 10. Verify cam timing. Refer to STANDARD PROCEDURE .
11. Faulty Camshaft Position (CMP) sensor. 11. Replace the Camshaft Position (CMP) sensor. Refer to SENSOR, CAMSHAFT POSITION, REMOVAL AND INSTALLATION .
12. Faulty Crankshaft Position (CKP) sensor. 12. Replace the Crankshaft Position (CKP) sensor. Refer to SENSOR, CRANKSHAFT POSITION, REMOVAL AND INSTALLATION .
ENGINE STALLS OR IDLES ROUGH 1. Idle speed too low. 1. Check for Diagnostic Trouble Codes (DTC). Refer to 2.4L - DIAGNOSTIC CODE INDEX .
2. Incorrect fuel mixture. 2. Check for Diagnostic Trouble Codes (DTC). Refer to 2.4L - DIAGNOSTIC CODE INDEX .
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 COIL, IGNITION, REMOVAL AND INSTALLATION .
5. Faulty Crankshaft Position (CKP) sensor. 5. Replace the Crankshaft Position (CKP) sensor. Refer to SENSOR, CRANKSHAFT POSITION, REMOVAL AND INSTALLATION .
6. Incorrect cam timing. 6. Verify cam timing. Refer to STANDARD PROCEDURE .
7. Oil Consumption 7. Low level range 3 Qts., check oil level and adjust as necessary.
ENGINE LOSS OF POWER 1. Dirty or incorrectly gapped spark plugs. 1. Correct as necessary. Refer to SPARK PLUG, REMOVAL AND INSTALLATION .
2. Contamination in fuel system. 2. Clean the fuel system and replace the fuel filter. Refer to MODULE, FUEL PUMP, REMOVAL AND INSTALLATION .
3. Faulty fuel pump. 3. Test and replace the fuel pump. Refer to MODULE, FUEL PUMP, REMOVAL AND INSTALLATION .
4. Leaking cylinder head gasket. 4. Replace the cylinder head gasket. Refer to CYLINDER HEAD, REMOVAL AND INSTALLATION .
5. Low compression. 5. Determine the cause and repair as necessary. Refer to DIAGNOSIS AND TESTING .
6. Burned, warped, or pitted valves. 6. Replace valves as necessary. Refer to VALVES, INTAKE AND EXHAUST, REMOVAL AND INSTALLATION .
7. Plugged or restricted exhaust system. 7. Inspect the exhaust system. Install new parts as necessary. Refer to INSPECTION .
8. Faulty ignition coil(s). 8. Test and replace the ignition coil. Refer to COIL, IGNITION, REMOVAL AND INSTALLATION .
9. Incorrect valve timing. 9. Verify cam timing. Refer to STANDARD PROCEDURE .
ENGINE MISSES ON ACCELERATION 1. Dirty or incorrectly gapped spark plugs. 1. Correct as necessary. Refer to SPARK PLUG, REMOVAL AND INSTALLATION .
2. Contamination in fuel system. 2. Clean fuel system and replace the fuel filter. Refer to MODULE, FUEL PUMP, REMOVAL AND INSTALLATION .
3. Burned, warped, or pitted valves. 3. Replace valves as necessary. Refer to VALVES, INTAKE AND EXHAUST, REMOVAL AND INSTALLATION .
4. Faulty ignition coil(s). 4. Test and replace the ignition coil. Refer to COIL, IGNITION, REMOVAL AND INSTALLATION .
ENGINE MISSES AT HIGH SPEED 1. Dirty or incorrect spark plug gap. 1. Correct as necessary. Refer to SPARK PLUG, REMOVAL AND INSTALLATION .
2. Faulty ignition coil(s). 2. Test and replace the ignition coil. Refer to COIL, IGNITION, REMOVAL AND INSTALLATION .
3. Contamination in fuel system. 3. Clean the fuel system and replace the fuel filter. Refer to MODULE, FUEL PUMP, REMOVAL AND INSTALLATION .
4. Dirty fuel injector(s). 4. Test and replace as necessary. Refer to DIAGNOSIS AND TESTING .
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