DIAGNOSTIC CHART
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(Life in case of normal use) |
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A worn spark plug not only wastes fuel but also |
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strains the whole ignition system because the |
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expanded gap requires higher voltage. |
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It also reduces the engine's efficiency, resulting |
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in reduced fuel economy and increased exhaust |
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emissions. Moreover, it contributes to pollution |
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Using Unleaded Petrol |
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generated by exhaust gas. |
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SYMPTOMS |
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CAUSES |
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REMEDY |
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• Hard starting |
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• Rich mixture |
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• Check float level |
• Misfiring |
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CARBON |
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• Retarded ignition |
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• Check choke |
• Black exhaust smoke |
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• Low compression |
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• Check ignition timing |
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FOULING |
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• Too cold a spark plug |
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• Check air cleaner |
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• Check compression |
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• Replace spark plug with correct heat range |
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• Hard starting |
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• Worn rings |
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• Replace worn components |
• Misfiring |
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• Worn piston |
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• Replace spark plug with correct heat range |
• Grey / white exhaust smoke |
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OIL FOULED |
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• Leaking valve stem seals |
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• Loss of oil |
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• |
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• Misfiring |
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• Fuel quality |
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• Replace spark plug |
• Hard starting |
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• Oil leakage |
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• Change fuel brand |
• No starting |
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DEPOSIT |
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• Engine operating period |
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• Repair engine (if need be) |
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• Misfiring |
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BREAKAGE |
• Engine noise |
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OF THE |
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INSULATOR |
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• Sudden change in temperature (Thermal shock) |
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• Replace spark plug |
• Oil leakage |
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• Check engine condition |
• Internal engine stress |
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• Repair engine (if need be) |
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• "Pinking" under acceleration or |
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• Lean mixture |
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• Check jets are not clogged |
climbing hills |
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• Advanced ignition timing |
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• Check float level |
• Engine |
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OVERHEATING |
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• Too hot a spark plug |
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• Check ignition timing |
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• Replace spark plug with correct heat range |
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• Misfiring |
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• Foreign particles inside cylinder |
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• Replace spark plugs |
• Loss of power |
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• Broken or damaged valve |
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• Remove foreign or damaged components |
• Hard starting |
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DAMAGED |
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• Noise in engine |
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• Hard starting |
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• Spark plug incorrectly torqued |
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• Replace spark plugs |
• Misfiring |
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UNDER |
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• Spark plug only handtightened |
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• Tighten spark plug to correct torque |
• Black exhaust smoke |
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• Dirt or carbon in threads of cylinder head |
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• Replace damaged components |
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TIGHTENING |
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• Check compression on all cylinders |
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• Hard starting |
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• Normal electrode wear |
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• Replace spark plug with correct heat range |
• Reduced fuel economy |
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• ± 0.03mm / 1 OOOkm |
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WORN |
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• Fuel deposits (carbon, lead, additives & salts) |
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• Hard starting |
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• Lean mixture |
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• Replace with correct heat range spark plug |
• Misfiring |
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• Advanced ignition timing |
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• Check air / fuel mixture |
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MELTING |
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• To hot heat range |
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• Misfiring |
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BREAKAGE |
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• Under tightening |
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• Correct tightening torques |
• Loss of power |
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• Noise in engine |
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OF THE |
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GROUND |
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ELECTRODE |
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• Misfiring |
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FOULING |
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• Excess MMT and Ferrocene |
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• Replace spark plugs with correct heat range |
• Hard starting |
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• Incorrect heat range |
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• Get to 450°C self cleaning temperature |
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• Reduced fuel economy |
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BY FUEL |
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ADDITIVE |
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