I have had my disco for about 2 years now and have rebuilt the engine (Flanged liners, Kent Cam, Grant rings and kept up most of the maintenance.
I have no way of knowing if the coil pack have ever been replaced. How do I know it's time to replace them?
What are the symptoms?
Why wait?
Thanks in advance.

 

well most of the time you loose one cylinder and it runs like crap. no reason to wait if you can afford to replace them.. I considered when doing my headgaskets changing them. but they were different so at least one was new. eventually the go bad. every car I've done them on was because the resin cracked and they were exposed internally to the elements