How to Install Spark Plug Wires

Gasoline combustion engines operate by exploding gasoline vapor in the combustion chamber, which drives the piston down, turning the engine crankshaft. Unlike diesel engines, gasoline engines require a spark to ignite the vapors. The electrical spark is created on the spark plug. The high-voltage, low-current electricity is delivered from the coil to the spark plug along the spark plug wire. Engines with more than one cylinder, such as automobile engines, require a number of spark plug wires to run from the ignition system to the spark plugs.

Things You'll Need

• Spark plug wire set
• Spark plug wire removal tool

Instructions

1. Remove the new spark plug wires from the box and lay them out according to size so you can easily match them up with the old wires. In the following steps, remove and replace one wire at a time.

2. Grasp the old wire at the spark plug with the removal tool and pull it off the plug. Follow the wire to the distributor cap or ignition coil and remove that end of the wire from its terminal.

3. Match up the old wire with a new wire, choosing the new spark plug wire closest in size to the old wire. Push the new spark plug wire firmly onto the spark plug and route it the same way the old wire was routed, using the same clips as the old wire, to the distributor cap or coil. Push the end of the wire onto the terminal. The metal clips inside the boots of the new wire must seat the wire terminal on the spark plug, distributor or coil terminal.

4. Repeat steps 2 and 3 until all the spark plug wires are replaced. Replace the coil wire that runs from the distributor cap to ignition coil on cars with distributor caps.

5. Start the engine. If the engine is running rough, turn it off and go over all the wires, making sure each one is firmly seated on the spark plug and on the ignition terminal.

Tips & Warnings

• The inside of the rubber boot at each end of the wire will slide over the spark plug quite a ways before the clip makes contact. Make sure you push each boot down until the metal clip is seated on the end of the spark plug. Specific spark plug kits are sold for specific models of cars, according to engine size and number of cylinders. Be sure to buy the kit that is correct for your car. Neatness counts. Keep everything neat and nicely routed so that wires are not burnt by touching hot engine parts.

• Don't just grab the spark plug wire and yank it off the spark plug. If you leave pieces behind, it can be difficult to get them off, especially in tight places. Replace one wire at a time. If you mix up the wires, the engine will not run or will run in a manner that may damage the engine.

References

• Spark plug wire replacement

Resources

• Ignition wire replacement