Q: How Do Spark Plugs Work in an Engine?

asked by on November 23, 2015

How do spark plugs work in an engine?

Spark plugs are used to ignite the air/fuel mixture in the combustion chambers of every internal combustion engine.

To accomplish this, spark plugs have two electrodes between which a high voltage spark will jump. One electrode is located in the center of the plug and one electrode is attached to the side of the plug.

The high voltage comes from an ignition coil and contains anywhere from 5,000 volts to 40,000 volts. The high voltage is necessary to overcome the air turbulence, compression pressure, and the air gap of the spark plug during the combustion cycle. The spark jumps from one electrode to the other. This spark ignites the air/fuel mixture in the combustion chamber. The combustion continues until all the fuel has been converted into heat and increased cylinder pressure. This is what creates the power inside of an engine.

Each spark plug fires one time for every two revolutions of the engine crankshaft.

If your vehicle is down on power or is getting less fuel economy, a fresh set of spark plugs may be in order. If you need help with this, schedule a visit with a certified technician who can check out the situation and replace your spark plugs if necessary.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Car runs rough until warm, and then runs fine.

I would have a technician inspect your rough idle. He will probably also check for codes on the computer. It may be the air temperature sensor malfunctioning if it idles rough only when it's cold. You may be able to...

Car misfires then goes to limp mode.

When the vehicle goes into limp mode when the engine misfires, the computer is shutting down the electronics to the transmission to prevent damage to the catalytic converter as the fuel condition is either too lean or too rich. Check...

Car cranking but not starting.

This vehicle engine and year has more than one possible failure for this complaint and no one stands out more than the fuel pump in the fuel tank. It is also possible that it could be could be a crank...

Related articles

What Does It Mean When an Engine "Knocks"?
If your engine is making a knocking noise it means there's a problem. The wrong fuel octane, carbon buildup, and bad spark plugs can cause knocking.
What Are the Best Spark Plugs for Normal Use?
Spark Spark plugs are essential components of your ignition system. They’re responsible for supplying the spark that ignites fuel and starts the combustion process. However, not all spark plugs are created equal. You’ll find “normal” plugs on the market, but...
How to Troubleshoot a Car That Won't Turn Off
If your car won't turn off, inspect the power relay, idle speed, ignition timing, and spark plugs. Using premium fuel may help but isn't a solution.