I have a '99 Discovery II 4.0 V8 that has serious ignition problems. It will start and run, but the plug wires are arching to ground and arching across from the boots to the base of all 8 spark plugs. I have replaced all plug wires and both coil packs with new parts and it still does it. Anyone have any info that would help me?

 

Did you replace the plugs?

It sounds like the porcelain insulator on the plugs themselves might be an issue, which is super rare. Also, dielectric grease in all of the boots is important as well to ensure a good seal between the boot and the plug.

 

X2 on replace the plugs. Bet this is quite a light display in the dark of night.