How to Change Spark Plugs in a Car

Changing the spark plugs in your car can make a difference your gas mileage. Your car needs a tune-up every 30,000 miles or so, and it is recommended that the spark plugs be changed about every 15,000 miles. Changing the plugs will help eliminate backfires, sputtering, misfires and sluggishness.

Things You'll Need

• Socket wrench with spark plug socket
• Spark plug gap gauge

Instructions

1. Find all the spark plug wires and trace them to the point where they connect to the engine block. Remove the first plug's wire and fit the spark plug socket around the body of the plug. Using the racket wrench, remove the spark plug.

2. Examine the spark plug and check the gap on the plug. White ash deposits on the electrode indicate that the spark plug has been firing hotter than usual. If there is a wet and black grimy look to the electrode, the plug has been burning oil. The gap of the electrodes also will give you an indication of the condition of the engine.

3. Take a new plug from the package and use the gap gauge to make sure the electrode gap is set to manufacturer's specifications. Each car uses a different gap. To close the gap, tap gently against the outer electrode with the end of the wrench. To widen the gap, use the adjustment wire on the gap gauge and narrow the gap. Screw the new plug into the engine block by hand to make sure the threads aren't cross-threaded. Tighten the plug with the socket wrench and reconnect the spark plug wire. Tighten the spark plug to one quarter turn past finger tight.

4. Repeat Steps 1 through 3 to change the rest of the plugs, whether there are four, six or eight spark plugs.