[COLVERT]

Originally Posted by roverbarmy

I had a V6 with leads on the front 3 and had the occasional misfire on damp days. A new set of leads cured the problem. The carbon in the leads starts to break down with age, heat, expansion and contraction, causing the spark to weaken, having to jump the gaps.

As the leads age and the insulation weakens the sparks find it easier to jump out through the sides rather than travel down the length of the leads. Any moisture around helps the electricity to track out through the sides.---