(Originally posted by clyde at autoindustriya.com)

I. Engine will not rotate when attempting to start :

1. Battery terminal connections loose or corroded.
2. Battery discharged or faulty
3. Broken, loose or disconnected wiring in starting circuit.
4. Starter solenoid faulty.
5. Starter motor faulty.
6. Ignition switch faulty.
7. Automatic transaxle/Continously variable Transaxle (CVT) not completely engaged in Park or clutch not completely depressed.
8. Starter pinion or flywheel teeth worn or broken.

II. Engine rotates but will not start:

1. Fuel tank empty.
2. Battery discharged.
3. Battery terminal connections loose or corodded.
4. Leaking fuel injectors, faulty fuel pump, pressure regulator, etc.
5. Fuel not reaching fuel rail.
6. Ignition components damp or damaged.
7. Worn, faulty or incorrect gapped sparkplugs.
8. Broken, loose or disconnected wiring in the starting circuit.
9. Loose distributor is changing ignition timing.
10. Broken, loose or disconnected wires at the ignition coil.

III. Engine hard to start when cold:

1. Battery discharged or low.
2. Malfunctioning fuel system.
3. Injector(s) leaking.
4, Distributor rotor carbon tracked.

IV. Engine hard to start when hot:

1. Air filter clogged.
2. Fuel not reaching the fuel injection system.
3. Corodded battery connections, especially ground.

V. Starter noisy or excessively rough in engagement:

1. Pinion or flywheel gear teeth worn or broken.
2. Starter mounting bolts loose or missing.

VI. Engine starts but stops immediately:

1. Loose or faulty electrical connections at distributor, coil or alternator.
2. Insufficient fuel reaching the fuel injector(s).
3. Vacuum leak at the gasket between the intake manifold and throttle body.

VII. Oil puddle under engine:

1. Oil pan gasket and/or oil pan drain bolt washer leaking.
2. Oil pressure sending unit leaking.
3. Cylinder head covers leaking.
4. Engine oil seals leaking.

VIII. Engine lopes while idling or idles erratically:

1. Vacuum leakage.
2. Leaking EGR valve.
3. Air filter clogged.
4. Fuel pump not delivering sufficient fuel to the fuel injection system.
5. Leaking head gasket.
6. Timing belt and/or pulleys worn
7. Camshaft lobes worn.

IX. Engine misses at idle speed:

1. Spark plugs worn or not gapped properly.
2. Faulty spark plug wires.
3. Vaccum leaks.
4. Incorrect ignition timing.
5. Uneven or low compression.
6. Fault in the fuel injection or engine control system.

X. Engine misses throughout driving speed range:

1. Fuel filter clogged and /or impurities in the fuel system.
2. Low fuel pressure.
3. Faulty or incorrectly gapped spark plugs.
4. Incorrect ignition timing.
5. Cracked distributor cap, disconnected distributor wires or damaged distributor components.
6. Leaking spark plug wires.
7. Faulty emission system components.
8. Low or uneven comperssion perssures.
9. Weak or faulty ignition system.
10. Vacuum leak in fuel injection system, intake manifold, intake air control valve (IACV) or vacuum hoses.

XI. Engine stumbles on acceleration:

1. Spark plugs fouled.
2. Fuel injection system faulty.
3. Fuel filter clogged.
4. Incorrect ignition timing.
5. Intake manifold leak.

XII. Engine surges while holding accelerator steady:

1. Intake air leak.
2. Fuel pump faulty.
3. Loose fuel injector wire harness connectors.
4. Defective ECU or information sensor.

XIII. Engine stalls:

1. Idle speed incorrect.
2. Fuel filter clogged and/or water and impurities in the fuel system.
3. Distributor components damp or damaged.
4. Faulty emissions system components.
5. Faulty or incorrect gapped spark plugs.
6. Faulty spark plug wires.
7. Vacuum leak in the fuel injection system, intake manifold or vacuum hoses.
8. Valve clearances incorrectly set.

XIV. Engine lacks power:

1. Incorrect ignition timing.
2. Excessive play in the distributor shaft.
3. Worn rotor, distributor cap or wires.
4. Faulty or incorrectly gapped spark plugs.
5. Faulty fuel injection system.
6. Faulty ignition coil.
7. Brakes binding.
8. Automatic transaxle/Continously Variable Transaxle (CVT) fluid level incorrect.
9. Clutch slipping.
10. Fuel filter clogged and/or impurities in the fuel system.
11. Emission control system not functioning properly.
12. Catalytic converter plugged.
13. Low or uneven cylinder compression pressures.
14. Obstructed exhaust system.

XV. Engine backfires:

1. Emission control system not functioning properly.
2. Incorrect ignition timing.
3. Faulty secondary ignition system (cracked spark plug insulator, faulty plug wires, distributor and/or rotor)
4. Fuel system malfunctioning.
5. Vacuum leak at fuel injector(s), intake manifold, air control valve or vacuum hoses.
6. Valve clearances incorrectly set and/or valves sticking.

XVI. Pinging or knocking engine sounds during acceleration or uphill:

1. Incorrect grade of fuel.
2. Ignition timing incorrect.
3. Fuel injection system faulty.
4. Improper or damaged sparkplugs or wires.
5. Worn or damaged distributor components.
6. EGR valve not functioning.
7. Vacuum leak.

XVII. Engine runs with oil pressure on:

1. Low oil level.
2. Short in wiring circuit.
3. Faulty oil pressure sender.
4. Worn engine bearings and/or oil pump.