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Do not get the term DIS (Distributorless Ignition System) confused with most modern ignition systems that no longer use a distributor or have multi-coil ignition systems. The original DIS systems introduced in the late 80's to early 90's were originally designed to reduce emissions by ensuring full burning of the air/fuel mixture. They did this by sending two sparks to the spark plug. A DIS ignition would fire twice as often as a conventional ignition system and change direction of fire. A conventional ignition fires on the compression stroke from the center electrode to the ground electrode. A DIS also fires on the compression stroke from the center to the ground electrode; however, the initial spark is stored and moments later, sent back through the ground to the center electrode usually as the engine is beginning its exhaust stroke. As this requires the spark plug to fire twice as often, it necessitated the advent of double platinum spark plugs which have platinum tipped ground and center electrodes or multi-ground spark plugs as the ground electrode would wear more quickly on these ignition systems. NGK laser platinum plugs have the highest platinum content in the industry, which is why NGK is one of the worlds leading supplier of O.E. double platinum spark plugs. |
