Backfiring is when an engine stops running briefly after a few seconds of running. It’s often a symptom of a mechanical or electrical issue. Cold spark plugs or worn-out plugs are usually the cause. Backfiring can damage your exhaust system and affect vehicle performance.
To stop it from happening, you need to know why. Here’s a guide to the most common causes and solutions:
What Causes a Car to Backfire?
A car backfire is when a combination of unburnt fuel and air enter the exhaust system. This leads to an explosion! Many things can cause this, such as:
- Incorrect ignition timing
- A blocked air filter
- A fuel system not functioning correctly
This article will explain what causes a car to backfire and how to fix it.
Improperly Timed Ignition
Backfiring of cars is often caused by improper timing of the ignition. If the spark plug does not fire at the correct time relative to the piston cycle, the fuel-air mixture can cause a loud bang instead of a smooth engine sound.
It can also occur when accelerating or slowing down. This is due to the engine performing differently under various loads and speeds. If timing adjustments aren’t made correctly, unburned fuel can enter the exhaust system and cause a loud pop – an “afterlife” or “backfire” based on where it occurs in the engine cycle.
Furthermore, if leaks are before the catalytic converter, extra air entering can cause more fuel burning than necessary. This leads to combustible material being produced with the fuel, which can result in backfiring. To avoid this, ensure that all components are working correctly.
Rich Mixture of Fuel and Air
Car backfires occur when the air and fuel mixture in the engine’s combustion chambers become too rich. This means there is an excessive amount of fuel and not enough air. This excess of energy igniting the exhaust system causes a loud bang, pop, or hiccup sound.
Backfires can happen during acceleration, deceleration, and even at idle. An imbalance of air and fuel in the carburetor or fuel injection system is the most common cause of backfiring during acceleration. If too much power is present compared to air, some will remain unburned and ignite outside the combustion chamber.
A lean air-fuel ratio typically causes deceleration backfires. Too much air compared to fuel in the cylinder chamber causes insufficient power to burn off during deceleration. It will then exit the exhaust pipe and quickly ignite, resulting in a loud noise.
Dirt particles can also contaminate the carburetor or fuel injection system. This can lead to imbalanced oxygen and hydrocarbon ratios, triggering combustion eruptions.
Faulty Spark Plugs
Faulty spark plugs are usually behind car backfires. They are devices in the combustion chamber of your engine’s cylinders that make electric sparks to ignite the fuel-air mix. If a spark plug is faulty, it can cause a backfire due to misfiring or incomplete combustion.
Newer cars use ignition coils to light up the spark plugs. Misuse or damage can still make them malfunction and lead to backfires. But this happens less often than with direct-fit spark plugs.
If you need to replace your spark plugs, check your manufacturer’s expected lifespan and performance requirements. Also, look up best practices on maintenance and repair of your make and model. Inspect all components routinely to avoid misfiring cylinders or fuel leakage. Finally, make sure any replacement parts meet industry standards.
How to Fix a Car Backfire
Several engine issues can cause a car to backfire. The most typical are:
- A spark plug is not working
- An old oxygen sensor
- A dirty fuel filter
- A malfunctioning fuel injector
Let’s learn how to spot and fix a backfire and get the car running again.
Check the Ignition Timing
To get your car backfiring the right way, start with the basics. Check the ignition timing by adjusting the spark. If your vehicle has one, this can be done by using a timing light. Attach it and follow the manufacturer’s instructions. If not, manually adjust the screws or bolts.
After adjusting the timing, take your car for a test drive. Drive for 3 minutes, with some bursts of speed. This will warm up the car.
When you backfire, that should burn away any extra fuel. If you don’t get the desired result, adjust a little bit at a time. Test again until it works.
Adjust the Air-Fuel Ratio
Backfires occur when extra fuel is burned in the exhaust system instead of the engine. This causes a loud bang, pop, or boom. The reason can be an improperly tuned engine, bad spark plugs, or ignition timing issues. To fix it, adjust the air-fuel ratio.
When the ratio is too lean, insufficient oxygen is present to burn all the fuel. So, some of the energy is left unburnt and ignites in the exhaust system.
To adjust the ratio, use an oxy-sensor gauge to measure the levels at different engine speeds and conditions. Tune the engine at idle first. Then increase the throttle inputs.
Resetting the air-fuel ratio is tricky. It’s best to leave it to a professional mechanic. They’ll identify which type of adjustment needs to be done before tuning. Once done, backfires should be gone!
Replace the Spark Plugs
A backfire in an automobile engine results from a misfiring cylinder in the combustion process. It produces excessive exhaust and can cause an audible ‘pop’ or ‘bang.’ This usually shows a maintenance issue, and replacing spark plugs or other components may be needed. Before buying parts, diagnose the problem correctly to save money.
To replace spark plugs:
- Find and remove the spark plug wires from each cylinder. Get a service manual to help identity which wires connect to which cylinder.
- Carefully remove the wire from the plug. Keep both the wire and its connector intact.
- Replace each plug with a similar model. Order platinum or iridium plugs, not double platinum, for longer life.
- Reconnect all wires. Make sure they’re securely connected for proper performance.
- Test your work. Start up the engine and listen for any backfires.
- Repeat steps 1-5 if necessary. If you hear backfires, repeat the steps on other cylinders till the problem is solved.
Car backfiring will draw attention. To make it happen without problems, switch the fuel injector’s timing. This causes a lean fuel mix and produces backfires. Don’t use this as a long-term solution – it can be dangerous. Get an experienced mechanic to tune your engine instead.
Frequently Asked Questions
What causes a car to backfire?
A car backfires when unburned fuel is ignited in the exhaust system, usually from a leak in the intake or exhaust manifold. This causes the power to ignite due to the heat of the exhaust, resulting in a backfire.
How can I make my car backfire?
You can make your car backfire by increasing the air/fuel ratio or installing an aftermarket exhaust system. Increasing the air/fuel ratio will cause the engine to run leaner, resulting in unburned fuel igniting the exhaust. Installing an aftermarket exhaust system will reduce the back pressure, allowing unburned fuel to ignite in the exhaust.
Is it safe to make my car backfire?
It is generally not safe to make your car backfire. If done improperly, it can cause damage to the engine or exhaust system. If you are unfamiliar with cars, having a professional make any modifications to your vehicle is best.