Engine Diagnosis - Performance
WARNING: This page is about a different car, the 2005 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. Test battery. Charge or replace as necessary. (Refer to ELECTRICAL/BATTERY SYSTEM - DIAGNOSIS AND TESTING) |
| 2. Corroded or loose battery connections. | 2. Clean and tighten battery connections. Apply a coat of light mineral grease to terminals. | |
| 3. Faulty starter. | 3. Test starting system. (Refer to ELECTRICAL/STARTING - DIAGNOSIS AND TESTING) | |
| 4. Faulty coil(s) or control unit. | 4. Test and replace as needed. (Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - GAS ) | |
| 5. Incorrect spark plug gap. | 5. Set gap. (Refer to ELECTRICAL/IGNITION CONTROL - SPECIFICATIONS) | |
| 6. Contamination in fuel system. | 6. Clean system and replace fuel filter. | |
| 7. Faulty fuel pump. | 7. Test fuel pump and replace as needed. (Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - GAS ) | |
| 8. Incorrect engine timing. | 8. Check for a skipped timing belt/chain. | |
| ENGINE STALLS OR IDLES ROUGH | 1. Idle speed too low. | 1. Test minimum air flow. (Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - GAS ) |
| 2. Incorrect fuel mixture. | 2. (Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - GAS ) | |
| 3. Intake manifold leakage. | 3. Inspect intake manifold, manifold gasket, and vacuum hoses. | |
| 4. Faulty ignition coil(s). | 4. Test and replace as necessary. (Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - GAS ) | |
| ENGINE LOSS OF POWER | 1. Dirty or incorrectly gapped plugs. | 1. Clean plugs and set gap. |
| 2. Contamination in fuel system. | 2. Clean system and replace fuel filter. | |
| 3. Faulty fuel pump. | 3. Test and replace as necessary. (Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - GAS ) | |
| 4. Incorrect valve timing. | 4. Correct valve timing. | |
| 5. Leaking cylinder head gasket. | 5. Replace cylinder head gasket. | |
| 6. Low compression. | 6. Test compression of each cylinder. | |
| 7. Burned, warped, or pitted valves. | 7. Replace valves. | |
| 8. Plugged or restricted exhaust system. | 8. Perform exhaust restriction test. (Refer to EXHAUST SYSTEM - DIAGNOSIS AND TESTING) Install new parts, as necessary. | |
| 9. Faulty ignition coil(s). | 9. Test and replace as necessary. (Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - GAS ) | |
| ENGINE MISSES ON ACCELERATION | 1. Dirty or incorrectly gapped spark plugs. | 1. Clean spark plugs and set gap. |
| 2. Contamination in Fuel System. | 2. Clean fuel system and replace fuel filter. | |
| 3. Burned, warped, or pitted valves. | 3. Replace valves. | |
| 4. Faulty ignition coil(s). | 4. Test and replace as necessary. (Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - GAS ) | |
| ENGINE MISSES AT HIGH SPEED | 1. Dirty or incorrect spark plug gap. | 1. Clean spark plugs and set gap. |
| 2. Faulty ignition coil(s). | 2. Test and replace as necessary. (Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - GAS ) | |
| 3. Dirty fuel injector(s). | Test and replace as necessary. (Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - GAS ) | |
| 4. Contamination in fuel system. | 4. Clean system and replace fuel filter. |