Testing coils on a coil over plug system?

[Ed Wright]

A leaky wire, boot or cracked plug can show up in gear and not idling in neutral. A little de-natured alcohol or soap in the water will break the surface tension so the water will cling to the plug wire, boot & plug, instead of bead up and not cover the entire surface. That will find small leaks quicker. I prefer the alky. A jumper wire, one end grounded and the other on a thin screw driver or ice pick will help find leaks too. Run the screw driver (or ice pick) along the coil's body, plug wire, boot and plug. a good digital lab 'scope is good for checking wave forms for the control circuit. If you are used to using them you can pick out a coil with an internal problem also by using the secondary clamp. I have an old Fluke 98A that still does that kind of work really well.