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.
Step 1
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.
Step 2
Disconnect the battery.
Step 3
Refer to the diagram and disconnect the mixed up spark plug wires.
Step 4
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.
Step 5
Connect the battery and start the engine.
References
Tips
- 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.
- 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.
Things You'll Need
- Vehicle owner's manual
- Toolkit
Warnings
- 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.
- Today's vehicles can shock you with high voltage. Always turn the car off and disconnect the battery when changing spark plugs or wires.
