Spark Plugs – Advice

Lost your Spark?
Spark plugs provide the spark needed to ignite the fuel and air mixture within the cylinders to power your engine and keep your car moving. Over time spark plug electrodes can wear down, crack, corrode and become coated in deposits, causing misfires, lack of acceleration, a rough and jittery sound being produced by the engine and a non-starting vehicle in the morning. It’s worth bearing in mind that faulty spark plugs can also drain your battery as well as potentially damaging other engine components.
Also, worn or damaged spark plugs can cause your car to fail its MOT emissions test.
Most vehicle manufacturers suggest having new spark plugs installed about every 30,000 miles however spark plug longevity depends on the condition and type of spark plug.

Spark plugs are fitted in petrol vehicles whereas glow plugs are fitted in diesel vehicles and these are used to preheat the cylinders to aid cold start as no spark is required to ignite a diesel engine; petrol engines are known as spark ignition engines because the spark plug ignites the fuel and air mixture and diesel engines are known as compression ignition engines as the fuel and air mixture is ignited by the air in the cylinder being compressed as the piston reaches the top of the stroke.

You will see from the photo that the spark plug on the right is corroded and the gap between the two points known as the electrode gap is greater than it should be making it more difficult for the spark to jump across.

Contact us for free advice if your vehicle is showing signs of worn spark plugs.

Mick Johns Garage Services's photo.