Engine Performance Diagnostic Table

WARNING: This page is about a different car, the 2015 Fiat 500. 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. Refer to DIAGNOSIS AND TESTING .
	2. Corroded or loose battery connections.	2. Clean and tighten battery connections. Refer to CLEANING .
	3. Faulty engine starting system.	3. Diagnose engine starting system Refer to DIAGNOSIS AND TESTING .
	4. Faulty coil or control unit.	4. Replace ignition coil. Refer to COIL, IGNITION, REMOVAL .
	5. Incorrect spark plug gap.	5. Correct as necessary.
	6. Incorrect cam timing.	6. Verify cam timing. Refer to STANDARD PROCEDURE .
	7. Dirt or water in fuel system.	7. Clean fuel system.
	8. Faulty fuel pump or wiring.	8. Repair or replace as necessary.
	9. Faulty Camshaft Position (CMP) sensor.	9. Replace sensor. Refer to SENSOR, CAMSHAFT POSITION, REMOVAL .
	10. Faulty Crankshaft Position (CKP) sensor.	10. Replace sensor. Refer to SENSOR, CRANKSHAFT POSITION, REMOVAL .
	11. Insufficient quantity of engine oil in the Variable Valve Actuation Assembly due to: Long term storage Engine not started within the last 30 days Replaced Variable Valve Actuation Assembly (MultiAir module)	11. Operate the starter to fill the Variable Valve Actuation Assembly with oil and enable its operation. CAUTION: Do not exceed 20 seconds of starter operation and allow 60 seconds cool-down between cycles.
ENGINE STALLS OR ROUGH IDLE	1. Vacuum leak.	1. Inspect intake manifold and vacuum hoses, repair or replace as necessary.
	2. Faulty Crankshaft Position (CKP) sensor.	2. Replace sensor. Refer to SENSOR, CRANKSHAFT POSITION, REMOVAL .
	3. Faulty ignition coil.	3. Replace ignition coil. Refer to COIL, IGNITION, REMOVAL .
	4. Incorrect cam timing.	4. Verify cam timing. Refer to STANDARD PROCEDURE .
ENGINE LOSS OF POWER	1. Dirty or incorrectly gapped spark plugs.	1. Correct as necessary. Refer to SPARK PLUG, REMOVAL .
	2. Dirt or water in fuel system.	2. Clean fuel system.
	3. Faulty fuel pump.	3. Replace fuel pump. Refer to MODULE, FUEL PUMP, REMOVAL .
	4. Leaking cylinder head gasket.	4. Replace cylinder head gasket. Refer to CYLINDER HEAD, 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 as necessary. Refer to VALVES, INTAKE AND EXHAUST, REMOVAL .
	7. Plugged or restricted exhaust system.	7. Inspect and replace as necessary.
	8. Faulty ignition coil.	8. Replace ignition coil. Refer to COIL, IGNITION, REMOVAL .
	9. Incorrect cam 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 .
	2. Dirt in fuel system.	2. Clean fuel system.
	3. Burned, warped or pitted valves.	3. Replace as necessary. Refer to VALVES, INTAKE AND EXHAUST, REMOVAL .
	4. Faulty ignition coil.	4. Replace ignition coil. Refer to COIL, IGNITION, REMOVAL .
ENGINE MISSES AT HIGH SPEED	1. Dirty or incorrectly gapped spark plugs.	1. Correct as necessary. Refer to SPARK PLUG, REMOVAL .
	4. Faulty ignition coil.	2. Replace ignition coil. Refer to COIL, IGNITION, REMOVAL .
	3. Dirt or water in fuel system.	3. Clean fuel system.