31/08/2025
🔹 Normal
• Appearance: Light tan/gray color on the insulator and electrode.
• Meaning: The engine is running properly, with the right air-fuel mixture and ignition timing.
🔹 Carbon Fouling
• Appearance: Dry, black, sooty deposits.
• Cause: Running too rich (too much fuel), dirty air filter, weak ignition, or excessive idling.
• Effect: Poor performance, misfires.
🔹 Overheating
• Appearance: White or blistered insulator, eroded electrode.
• Cause: Engine running too lean (not enough fuel), incorrect spark plug heat range, or cooling problems.
• Effect: Engine knocking, possible engine damage.
🔹 Pre-Ignition
• Appearance: Melted or damaged electrode.
• Cause: Fuel igniting before the spark (due to hot spots, low-octane fuel, or excessive compression).
• Effect: Severe engine knocking and potential piston damage.
🔹 Oil Fouling
• Appearance: Wet, oily deposits.
• Cause: Oil leaking into the combustion chamber (worn piston rings, valve seals, or cylinder walls).
• Effect: Misfires, blue smoke from exhaust.
🔹 Mechanical Damage
• Appearance: Crushed, broken, or bent electrodes.
• Cause: Foreign objects in the cylinder or piston-to-plug contact.
• Effect: Serious engine damage if not fixed.
🔹 Torched Seat
• Appearance: Burnt or melted plug seat area.
• Cause: Extremely high combustion temperatures, wrong plug installation, or detonation.
• Effect: Risk of plug failure, engine overheating.
🔹 Broken Insulator
• Appearance: Cracked or missing ceramic insulator.
• Cause: Poor handling, detonation, or improper installation.
• Effect: Misfire, engine damage risk.