DIAGNOSIS AND TESTING - ENGINE DIAGNOSIS - PERFORMANCE


CONDITION
POSSIBLE CAUSE
CORRECTION
ENGINE WILL NOT START
 		1. Weak battery.
 		1. Test battery. Charge or replace as necessary
(Refer to 8 - 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 8 - ELECTRICAL/STARTING - DIAGNOSIS AND TESTING)
4. Faulty coil(s) or control unit.
 		4. Test and replace as needed. (Refer to Appropriate Diagnostic Information)
5. Incorrect spark plug gap.
 		5. Set gap. (Refer to 8 - 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 Appropriate Diagnostic Information)
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 Appropriate Diagnostic Information)
2. Incorrect fuel mixture.
 		2. (Refer to Appropriate Diagnostic Information)
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 Appropriate Diagnostic Information)
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 Appropriate Diagnostic Information)
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 11 - EXHAUST SYSTEM - DIAGNOSIS AND TESTING) Install new parts, as necessary.
9. Faulty ignition coil(s).
 		9. Test and replace as necessary. (Refer to Appropriate Diagnostic Information)
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 Appropriate Diagnostic Information)
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 Appropriate Diagnostic Information)
3. Dirty fuel injector(s).
 		3. Test and replace as necessary. (Refer to Appropriate Diagnostic Information)
4. Contamination in fuel system.
 		4. Clean system and replace fuel filter.