You’ve heard the boom behind your car while driving and you know what it is. But do you know what causes an engine backfire?

This is a common problem that millions of drivers encounter. An engine backfire is the combustion of fuel and air in the air intake or exhaust creating a loud popping sound. This is usually accompanied by black smoke coming out of your car’s tailpipe. Here are the three most common things that cause engine backfire.

1. Engine Running Rich

Automotive engines operate with a precise ratio of fuel to air. To create combustion, the engine needs a specific amount of fuel and air for each cylinder stroke. If it receives too much fuel and not enough air, this is “running rich.” This often leads to engine backfire. With an excess amount of fuel pumping into your engine's combustion chamber, some of it may not get burned. And any remaining, unburned fuel will travel out the exhaust causing engine backfiring.

2. Engine Timing is Off

This happens when the upper part of the cylinder head isn't synchronized with the bottom part. It causes your car's engine to trigger ignitions at the wrong time. If it triggers one when the exhaust valve opens, it allows some unburned fuel to escape. This causes engine backfiring.

3. Damaged Catalytic Converter

Your car’s catalytic converter is between the engine and exhaust system. It’s responsible for converting harsh, toxic gasses into less-harmful gasses. Its honeycomb design filters and converts exhaust gasses before exiting through the tailpipe. Catalytic converters degrade over time. This increases the risk of backfiring. A failed catalytic converter might cause small amounts of fuel to accumulate. After enough builds up, the heat inside the exhaust system or the engine bay can ignite the fuel. This causes engine backfire.

How to Fix Engine Backfire

If you know what’s causing it and you're handy with repairs, you probably can fix it. The key is having the right tools for the job. If running rich is the issue, you’ll need a vehicle diagnostic tool, spark plug wrench, and oil filter wrench. If it’s engine timing, you’ll want a reliable distributor wrench and other hand tools. And for replacing a catalytic converter, a jack stand, ratchets, and sockets will come in handy. All these tools and more are waiting for you in the JB Tools online inventory. Type what you’re looking for in the search bar and get the best prices on the tools you need!