How to Fix a Spark Plug Wire Mix Up

by WadeH

Your car coughs and jerks down the road after an amateur spark plug change--chances are you mixed up the spark plug wires. The "firing order" of the spark plugs refers to the order in which the distributor sends electricity to the spark plug. If the spark plug works, it sparks when it receives electricity. For a 4-cylinder car, the firing order is 1-2-3-4. For an 8-cylinder vehicle, the firing order is 1-2-3-4-5-6-7-8. Of course, firing order depends on how you number the plugs. You probably just crossed a couple of wires.

Find the firing order information. Look in a Haynes or Chilton manual or call the dealer or an auto parts store. Find the diagram that shows the firing order of the plugs and how they connect to the distributor.

Disconnect the battery.

Refer to the diagram and disconnect the mixed up spark plug wires.

Reconnect the spark plug wires to their corresponding spark plugs. Trace the spark plug wire from the distributor to the correct spark plug. Ensure that both ends are tightly connected.

Connect the battery and start the engine.

Tips

  • check Avoid the mix up completely by changing one spark plug at a time and reconnect the spark plug wire before moving to the next spark plug.
  • check Some vehicles don't have a distributor, but they all have a device that performs the same function. Even distributorless systems have some device that sends electricity to the spark plugs.

Warnings

  • close This type of error is more noticeable in a 4-cylinder vehicle than an 8-cylinder. Each cylinder has a spark plug. If you cross wires with a 4-cylinder vehicle, you only have 2 cylinders running correctly. If you cross wires on an 8-cylinder vehicle, you still have 6 cylinders to power the engine.
  • close Today's vehicles can shock you with high voltage. Always turn the car off and disconnect the battery when changing spark plugs or wires.

Items you will need

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.

Photo Credits

  • photo_camera spark image by Zbigniew Nowak from Fotolia.com