My Bug used to eat coils for lunch. Finally traced it to the combination of the steel braided cables I installed that were arcing, as well as the resistors were bad as well. The arcing would burn out the resistors to the point that I would have to keep a couple of spare coils and resistors whenever I went on a long trip...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car