How to Put on a Coil Boot Plug

Coil boot plugs are becoming the standard in newer vehicles, replacing the old coil and spark plug wire system. With a coil boot, or coil-on boot plug, each spark plug has its own ignition coil, rather than a series of coils that are all fed through one cable and then dispersed through a distributor cap. As long as your vehicle is already converted, or came with a system that uses these kinds of plugs, the process to put on a coil boot plug is easy.

Things You'll Need

  • Dielectric grease
  • Coil-on boot plugs
  • Remove the coil-on boot connectors from their packaging. Make sure that you have the right type of plugs for your make and model of car; these are not "one-size-fits-all" items. Examine each boot plug to make sure that the outer insulating rubber is in good condition. If you are satisfied that the coil boot plugs are in good shape, continue on to the next step. If, for any reason, you doubt the integrity of the rubber insulation, return the plugs to the store you purchased them from and get another set. The smallest defect can lead the plugs to fail.

  • Lightly coat the connector to the coil pack with dielectric grease. The coil pack is the tubular end of the boot plug that will then be plugged into the receiving starter relay. Unlike the spark plug connection, this connection is not inside a boot but the brass of the connection is clearly visible outside of the boot.

  • Plug the coil connector end into one of the receiving openings on your starter relay module. Your module will have an equal number of openings as your vehicle has spark plugs. It does not matter which one the boot lug is connected to as the firing order is automated.

  • Grab the boot end by the rubber and push it over the end of the spark plug until you feel it click into place. Your coil boot plug is now on. Continue to connect the remain spark plugs to their individual coil-on boot plugs.