Why engines backfire

Sometimes a flame can be seen when a car backfires, but mostly you will only hear a loud popping noise, followed by loss of power and forward motion. That unburnt fuel can be caused by a variety of mechanical problems, and here are some of the most common reasons for a backfire:. If your engine is getting more fuel than it needs, a rich fuel to air ratio is the result. When your car has leftover fuel in the exhaust and the cylinders, that fuel explosively burns and creates a loud popping sound.

Specifically, here we mean delayed timing, which causes the backfire. But hunting season is over, and you're sure it didn't come from a neighboring yard — so what was that loud POP!? It's not a gun and it's not a firecracker. It's your car backfiring! Here are the basic steps your internal combustion engine follows to turn fuel and air into horsepower:.

The intake valve on your fuel cylinders opens, pulling a mixture of fuel and air into the engine. The exhaust valve opens and closes, allowing smoke and residue from the combustion process to escape through the tailpipe.

The entire process occurs on repeat while your engine runs, with multiple pistons and cylinders working together to make the wheels on your bus or car go round and round. Typically, a backfire takes place when one of the above explosions occurs outside your fuel cylinders.

Backfires and afterfires are worth paying attention to since they can cause engine damage, power loss, and decreased fuel efficiency. The right ratio of fuel and air is critical to proper engine combustion. When an engine is running rich, it has too much fuel and too little air, which slows down the combustion process. If you think your vehicle is running rich or lean, have a trusted expert at Firestone Complete Auto Care inspect your engine.

We'll look for the following troublemakers:. In newer vehicles, computerized sensors help ensure the air-fuel ratio is correct. However, if a sensor malfunctions, it can throw off the air-fuel ratio, causing sluggish or delayed combustion.

If this is the case, your Check Engine light might be screaming at you. Leaks in the exhaust system, sometimes called vacuum leaks, can sound more like a screech than a bang as excess air gets sucked in. All this extra air mixes with the fuel, creating an incorrect ratio for proper combustion. Even something as simple as a dirty air filter can potentially trigger a backfire.

Since air filters allow clean air to flow into your engine, a dirty filter can inhibit the flow of air into the intake, creating a poor fuel-air ratio.

Injectors that supply too little or too much fuel to the cylinder can also create a poor fuel-air ratio. Is the small engine on your lawn mower, snow blower or outdoor power equipment making loud noises?

Backfire is a condition described as a loud bang, poof, explosion, etc. Afterfire occurs after the engine has been shut off. Note: Backfire and afterfire through the carburetor will not harm the engine at all! Find out the most common causes and possible fixes for engine backfire and afterfire.

Backfire typically occurs when the engine is decelerated rapidly. Common Causes of Backfire:. Common Causes of Afterfire:. Learn how to properly and safely use, troubleshoot, and maintain your lawn mower, tractor, snow blower, and other lawn and garden equipment. View How-To Articles.

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