Spark Plugs – The Good, the Bad, and the Buildup
The spark plug uses the energy produced by the ignition coil to generate the spark necessary to ignite the air/fuel mixture in the combustion chamber.
Inspecting Your Vehicle's Spark Plugs
Normal wear and tear: the firing end should be gray or a brownish tan in color and relatively clean, indicating a normal running engine.
Ash deposits: Too much oil in the combustion chamber or low quality oil/fuel can cause light brown deposits to form around the electrodes and insulator. This development leads to misfiring and hesitation.
Carbon Fouling: Resulting from an over saturated fuel/air mixture, a clogged air filter, or a malfunctioning choke operation, dry black residue on the plug can cause misfire and a weak spark.
Oil Fouling: Resulting from either valve guides (in 4-stroke engines), too much lubricant (in 2-stroke engines), or oil leaking beyond the piston rings, wet oily residue forming on the plug can cause misfire and a weak spark.
Overheating: A malfunction in the ignition or cooling systems or using the wrong type of fuel can cause blistering along the white insulator and glazed electrodes.
Worn Out: Electrodes subject to significant wear and tear will have trouble starting in cold or moist conditions.
How Do I Replace My Spark Plugs?
Learn how to replace your vehicle's spark plugs with RepairPal Bret in the video below.