To ensure good anti-knock performance in gasoline, increasing the content of iso-octane is a crucial method. Some manufacturers add MMT during the refining process, while others include MMT in fuel additives. MMT primarily consists of methylcyclopentadienyl manganese tricarbonyl compounds. After combustion in the engine, it produces manganese oxide, magnetite (Fe₃O₄), and ferric oxide (Fe₂O₃), which can foul spark plugs and other components. This residue is often recognized by its characteristic rusty or tea-brown color.
Carbon fouling refers to the phenomenon where the firing end of the spark plug is covered in black carbon deposits, typically caused by a rich air-fuel mixture, incomplete combustion, using spark plugs with an incorrect heat range (too high), or prolonged low-speed engine operation.
The key difference between MMT fouling and carbon fouling, aside from the color of the deposits, lies in how they affect engine performance. Carbon fouling causes misfires at any temperature, though carbon deposits may burn off when the spark plug temperature exceeds 500°C. While carbon fouling can sometimes be removed using a specialized cleaning machine, such equipment and the required expertise are not always available-thus, replacing the spark plugs is generally recommended. If the deposits are wet carbon, cleaning is no longer an option, and replacement is the only solution.
In contrast, MMT fouling leads to misfires only when engine RPM increases and spark plug temperatures rise. Once fouled by MMT deposits, the spark plug cannot be cleaned and must be replaced.
Premium spark plugs use precious metals like iridium and platinum, which offer far better heat resistance and corrosion resistance compared to standard nickel alloys.
This reduces the contact area between flame and metal, effectively minimizing energy loss and improving ignition efficiency, making it a great option for drivers seeking better throttle response and fuel economy.
The ceramic in a spark plug isn't just for insulation - it also plays a crucial role in heat dissipation and structural durability.
