Q: How to check spark plug wires and Distributor Cap when new spark plugs are installed?
A: Just like the spark plugs, the ignition cables should be examined. Start this process by watching the wires in a running engine. Begin by starting the engine in a dimly lit room and observing each wire without risking touching any moving parts of the engine. If there is a break in the wire, you will see an arc or a little spark at that place. Should arcing occur, make a note to buy new wires, then let the engine cool down and check the distributor cap together with rotor. Inspect one wire at a time to avoid mixing up their order which could interfere with efficient running of the engine. Put numbers on each original plug wire or mark them with tape so as to identify where they belong. Remove the rubber boot from spark plug using removal tool or pull it off by hand then check inside for corrosion. Push boot back onto end of spark plug ensuring tight fit. Use pliers to crimp metal connector inside wire boot if necessary. Take clean rag and wipe entire length of wire checking for burns, cracks and other damage caused by dirt and grease. The conductor may be broken when you bend it sharply so don't do this.Do not fold or sharply bend wires; otherwise, they will break away from their conductors.Disconnecting it from distributor can be done by pulling on rubber boot and check for corrosion as well as a tight fit between them.Press it back into distributor.The rest of the spark plug wires should still be hooked up tight at both ends.If necessary to replace worn out spark plug wires, purchase a set for your particular engine brand and change them individually to prevent confusion regarding firing order.Pull off clips holding distributor cap then inspecting it for presence of cracks, carbon tracks, and any worn or loose contacts.Remove rotor from distributor shaft and examine for cracks and carbon track.Replace cap and rotor when damage appears.Should you decide on reusing old cap then clean terminals before reinstalling.To avoid mishaps such as mix-ups in firing order, remove wires from old cap one at a time when you install new cap and attach them to new cap at similar locations.