What Does a Spark Plug Do?

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Your ignition system is pretty complex, and there are a number of important components that must work with one another to crank the engine and then keep it running. Your spark plugs are among the most important of these, and you have several of them (one per cylinder).

The job of your spark plugs

Spark plugs have a very simple yet essential job. They provide the spark necessary to ignite gasoline in the combustion chamber. Without working spark plugs, your engine will not run (there will be nothing to ignite the fuel and start the combustion process). Your car’s engine basically runs on a series of miniature, contained explosions. First, air and fuel are mixed in each cylinder. When the piston rises toward the top of the cylinder, the spark plug fires. Electricity arcs from the electrode to the tab, and the fuel and air mixture ignites. This creates pressure as the fuel is transformed into a gas (emissions), which pushes the piston back down and turns the engine. This cycle is repeated over and over again in each cylinder of your car.

The engine has one spark plug per cylinder. Each spark plug is connected to a spark plug wire (in conventional and electronic ignitions). The wire runs from the top of the plug to the distributor, which is attached to the coil. However, if you have a distributor-less ignition, you have no spark plug wires. Rather, coil packs are used and the whole system is controlled by the computer.

Over time, your spark plugs wear. This is completely normal. Eventually, they will need to be replaced. The primary form of wear is to the electrode – as the spark plug arcs, it loses tiny amounts of electrode material. Eventually, it shortens. When it becomes too short, it won’t arc properly and the engine will misfire.


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Pardeep

20 years of experience
652 reviews
Pardeep
20 years of experience
Ford Fusion - Brake Pads Replacement (Rear) - Fremont, California
Again 5 star service. And already scheduling him for my next appointment. Highly recommend Pardeep for your car needs.
Chevrolet Camaro - Brake Pads Replacement (Front) - San Jose, California
Great knowledgeable mechanic and fast great work. I will use Pardeep and your services again. Thank you

Theodore

15 years of experience
1137 reviews
Theodore
15 years of experience
Toyota Camry - Brake Pads Replacement (Front) - Everett, Washington
Theodore arrived on time, he did a great job replacing my brakes on my Camry, I will definitely work with him again.
Subaru Outback - Brake Pads Replacement (Front, Rear) - Renton, Washington
We have had previous work done by Theodore. Really appreciate his thoroughness and professionalism!

Matthew

32 years of experience
734 reviews
Matthew
32 years of experience
Jeep Wrangler - Brake Pads Replacement (Front) - Yorktown, Virginia
We've been using Your Mechanic services for a few years, for a few reasons. The convenience of having an expert mechanic "on-call," the great pricing and transparency for services (saving 10% - 25% at times), most of all Matt is our go-to guy who is highly qualified, knowledgeable in the work and knows how to explain it to us in detail.
Ford F-150 - Brake Pads Replacement (Front) - Newport News, Virginia
Matt's technical knowledge of his profession is incredible! He is prompt, thorough, friendly, professional, engaging, and completes the job to 100% perfection! Thank you, Matt for the most outstanding auto repair service in all my many years!!!

Jason

31 years of experience
162 reviews
Jason
31 years of experience
Nissan Altima - Brake Pads Replacement (Front) - San Mateo, California
Jason was very professional and friendly. He provided extremely honest and helpful advice on issues with my Altima that would require proactive future maintenance.

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