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Excessive Wear

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Problem: Excessive wear
This plug is worn out. Note how both electrodes are showing extreme wear, thereby creating a huge gap. Naturally, this large gap will affect how the plug performs. The voltage required to fire a plug like this has effectively doubled and will continue to increase the longer the engine operates. Further, even higher voltage requirements may occur when the engine is accelerated quickly. Expect poor engine performance and a loss of fuel mileage.