The distributor cap is an important component of your Volkswagen’s ignition system that safeguards the internal components of the distributor. The timing & firing will be effective as long as it is in pristine order. So, replace it timely when it goes bad for a trouble-free ride. Have the entire diagnosis done by a trained car-geek to avoid getting into the unwanted mess. Have a look at this slide for more information about the symptoms of its failure.