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Why Does an Engine Backfire? FAQs

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The crackling sound that gives goosebumps, flames hot enough to melt metals shooting out of the exhaust…an engine backfire is a pleasant treat for our senses for sure, but is it actually good for your car? Why does an engine backfire after all?

Engine backfires are fun when you think of it from your perspective, but not always so when you think of it from the engine’s perspective. And when it is your Honda Civic or Chevy Silverado, engine backfires start worrying you a lot if you know what that means. The point is, if your car is backfiring often, it is not good for the engine at all if not bad, and you should keep an eye on it unless your car is a Lamborghini Aventador or a Bugatti Chiron.

No, we’re not saying that you will have to do a repair that costs $4000, but that’s on the cards if you keep driving it enjoying the backfires. However, it’s usually an under $100 repair if you diagnose and take it to a mechanic before it gets too bad.

This article is intended to educate you on all aspects of engine backfires, from the basics like why does an engine backfire to the damages to the engine parts that can cause engine backfires on acceleration, deceleration, and on start.

Engine Backfire: Frequently Asked Questions

What is an engine backfire?

The combustion of the air-fuel mixture, which ultimately moves the vehicle forward, should take place only inside the combustion cylinders for maximum power and efficiency. An engine backfire occurs whenever the combustion takes place outside of the combustion cylinders. The fuel explodes in the exhaust system, and it sounds like a firecracker explosion.

Why does an engine backfire?

An engine can backfire due to a variety of reasons, ranging from bad engine timing and imbalance in the air-fuel mixture to a faulty spark plug or ignition coils. In general, damages to the ignition or the combustion system is the major reason behind engine backfires. If white smoke is coming out of the exhaust, it might be indicating a different problem.

What causes engine backfire on acceleration?

When you accelerate, the spark plugs start producing more sparks, and more air-fuel mixture reaches the combustion cylinders. If your car backfires on acceleration, it means that there’s more fuel in the combustion cylinders but not enough sparks to burn all the fuel. So unburnt fuel reaches the exhaust, resulting in backfires.

Why does my car backfire when I turn it off?

If your car backfires when you turn it off, it means that the fuel is escaping out of the cylinders before combustion. It may be indicating that your car has a rich air-fuel mixture, faulty spark plugs, or an incorrectly timed exhaust valve.

Can backfires damage the engine?

Yes. To begin with, if your engine is backfiring, it means that your engine is not producing enough power as it should. Engine backfires and loss of power complement each other. It also indicates that there is something wrong with your ignition system.

Can spark plugs cause backfire?

clogged spark plug causes backfire

Yes, faulty or clogged spark plugs can also cause backfires. The sparks generated by the spark plugs ignite the air-fuel mixture in the combustion cylinders. If one of the spark plugs is faulty or clogged, it will not produce enough sparks to burn the air-fuel mixture completely, resulting in the mixture leaking to the exhaust and so the engine backfires.

How do I stop my engine from backfiring?

First, you need to find out the root cause behind the backfires. It could be faulty ignition coils, spark plugs, clogged fuel injector or carburetor, incorrect intake or exhaust valve timing, or lean or rich air-fuel mixture.

Once you find what’s causing the backfires, you can fix it yourself if it is the ignition coil or the spark plug. If it is something more complex, it’s better to take it to a mechanic.

How to fix backfires caused by spark plugs?

The shortest answer is to replace the spark plugs. The long answer would be to clean and adjust your spark plug if it still can be used. Clear the carbon deposits out of the spark plug electrodes, and make sure the spark plug is gapped as per the manufacturer’s recommendations. As a general rule of thumb, the gap should be between 0.025″ and 0.055″.

Why do sports cars backfire?

Well, sports cars eat up a lot of fuel. Since they accelerate and decelerate too fast, the amount of fuel in the combustion chamber varies each second, and so the chances of leaving some fuel unburnt are more. To give you a rough idea, the average mileage of a Lamborghini Aventador is 11 miles per gallon. Also, the ECM takes a split second to adjust the air and fuel intakes, which can result in backfires.