Changing Spark Plugs – 6 Superb Benefits

• Improved Engine Performance
• Smoother Engine Operation
• Reduced Emissions
• Improved Fuel Economy
• Longer Engine Life
• Smoother Idling

Five symptoms of bad spark plugs

• Misfiring engine - this will cause your engine to lose power momentarily before regaining speed. You might also notice a loud popping sound and black smoke.
• Trouble starting - without functioning spark plugs, your engine won't be able to start.
• Slow acceleration - a common symptom when there's a fault with the ignition system.
• Poor fuel economy - faulty spark plugs significantly impact fuel consumption.
• Black exhaust smoke - unusual smoke usually accompanies engine misfires.

Step-by-Step Instructions

Removing the Old Spark Plugs

Step One
Locate the spark plug (some applications the spark plug might be hidden under the upper intake manifold, Ignition coil or ignition coil cover); locate the wire connected to the spark plug or ignition coil. Pull on the boot - the connector at the end of the wire or unplug wiring connector on the coil. Be sure not to pull on the wire itself, you risk damaging the wire or wiring connector. 

Step Two 
After the wire or coil is removed, use your socket wrench with the spark plug socket to remove the spark plug. Place the socket around the spark plug and turn the socket counterclockwise. The spark plug should unscrew easily.  If you are having problems removing a spark plug that is too tight, stop before you break it off.  You can put a bit of penetrating oil like WD-40 to help loosen it. 

Step Three
Take a look at the old plug; it should be a little dirty on the end. If it is oily or white, this could point to other issues that you need to investigate with the help of a professional mechanic. Set the old spark plug aside.  

Step Four
Examine the threads in the engine, if they are dirty; clean them with a thread cleaning tool. 

Installing the New Spark Plugs

Step One
If necessary, set the gap on the new spark plug before installing it. In the past, it was necessary to use a gapping tool to make sure the gap in the spark plugs was the correct size. Most spark plugs sold on the market today are pre-gapped, eliminating the need for this step. But you should double check that the gap is correctly set; check your owner’s manual to find the distance for the spark plug gap and use a gap gauge or feeler gauge to check the distance. 

Step Two
Seat the new spark plug by hand; turning it clockwise at least two full turns. Once you have the spark plug snug, use the socket wrench with extension and spark plug socket to tighten it turning the plug clockwise. The plug’s washer should be pressed against the mounting surface.  
Take care not to over tighten the plug; you can strip the thread on the head of the engine leading to costly repairs. You can also use a torque wrench to torque it to specification. 

Step Three 
Replace the spark plug wire boot or ignition coil and wiring connector. A plastic boot should click into place while a rubber boot may require a coat of dielectric grease on the inside of the boot for easy removal next time. 

Step Four 
Repeat the removal and installation process for each spark plug.