Ignition Leads/ Spark Plug Wires
Ignition leads carry a high voltage current from the coil to the spark plugs. They also must prevent RF frequency leakage which can effect on board computers as well as interfere with car radio reception.
Various insulating materials are used around the central conductor such as EPDM and Silicon. These insulating sleeves can start to deteriorate and cause cross fire and engine roughness or the inner core can breakdown and cause a miss or one cylinder fails to fire.
The solution is to replace that one lead although if one lead has failed it is good practise to replace the lot.
Again more modern cars have introduced a system where the engine coils are mounted on top of the spark plug doing away with the need for ignition leads.
Lilydale Auto Electrical can test your ignition leads and replace these if necessary.