One of the first lessons learned in driver’s education is that an unusual sound from a car warrants investigation. Even if you hear something once and never again, there might be an issue to resolve.
A noise that you can hear frequently while driving is a popping noise while accelerating or immediately after.
What causes that sound? Is it easy to fix?
When the engine starts popping, is it necessary to visit a mechanic? The answers to those questions are found below.
Popping Noise on Acceleration?
When you hear popping or crackling sounds from a vehicle, it is usually due to unused fuel exiting the engine. It gets ignited by the hot exhaust system to create unwanted sounds. It often happens after hard acceleration, right when the throttle gets left off, because an overrun occurs.
You’ll notice the popping sound from an acceleration issue when you accelerate quickly or let off the pedal right away after a hard drive. Some vehicles might lurch or hesitate during that moment, but it restores functionality almost immediately.
Since some unspent fuel gets sent along the exhaust route, the popping sounds can sometimes feel like they come from the car’s center instead of the front. It can even be reminiscent of the “backfire” that happens with older vehicles where flames come out of the back pipe.
Although acceleration is the primary cause of popping noises today, you could be experiencing unusual sounds for several different reasons. Here are the most common ways a backfire occurs in a modern vehicle.
◼️ Why Is My Car Backfiring?
| Fuel Mixture Richness: | • When your engine gets more gasoline than it needs to perform, you get a richer fuel-to-air ratio occurs. • If there is leftover fuel in the cylinders and exhaust, it will burn explosively to create an unwanted popping sound. |
| Incorrect Engine Timing: | • If your car’s engine has delayed timing, it can cause a backfiring issue that sounds like a popping noise. • This problem happens when the ignition cycle starts later in the chamber, igniting the fuel when the exhaust valve starts opening instead of waiting for it to be open entirely. |
| Carbon Tracking: | • Should there be carbon tracking on your spark plug wires, a gentle popping sound can develop from the front of the car. • Sparks start switching from wire to wire, eventually creating a shortcut that results in unwanted noise. • When it splits paths, some fuel can get left behind in the cylinder. |
| Cracked Distributor Cap: | • If your car doesn’t have an ignition coil on the spark plugs, it has a distributor cap. • The wire set disperses the electrical spark to the plugs. • This process can get disrupted if moisture seeps through a crack in the system, causing the current to jump to the incorrect location. |
If you are dealing with a car that seems to be constantly backfiring or creating a popping noise on acceleration, it might be time to have the issue looked at professionally.
Although most problems are minor, especially after you’ve driven the vehicle hard, there is always a slight risk that the repetitive sounds could be evidence of something more severe.
◼️ What Else Could Be Causing the Popping Sound?
If you have an older vehicle, especially a truck, there could be ball joints in the front suspension. These components can sometimes generate a popping sound when going over a bump in the road or navigating a tight corner.
These sounds are usually nothing to worry about if you’ve been completing your regularly scheduled maintenance for the vehicle. It’s the normal activity from the joint.
You’ll still need to get the parts checked out if the popping happens around each curve or bump because that issue could be evidence of a worn-out component.
The popping sounds that happen when turning sharply or going over a pothole can also signify that your shocks or struts require replacement.
How to Troubleshoot the Popping Noises from Your Engine
The popping sounds from the engine compartment can come from several locations. If you’ve been driving the vehicle for a few months, you’ll have a feeling for what is considered a “normal” sound and what you’d classify as “unusual.”
When you get a heavier knock, it might be due to the acceleration you’re performing while under a heavy load. Some noises increase or decrease based on the engine RPMs.
If you know how the engine works, it can help you understand what parts create unwanted popping sounds. The best way to determine a result is to use a process of elimination so that you can pinpoint the problem.
These steps can help you start the troubleshooting process to determine what might be happening with your vehicle today.
◼️ Steps to Follow When Checking on a Popping Noise
- Start by placing the vehicle in park. You can also use the neutral setting while activating the emergency brakes.
- Get the engine going. Once you’ve turned the key or pressed the button, you can step out to open the hood.
- Try to determine the general location where the popping sound originated. You’ll want to check the belts and pulleys, ensuring that they’re rotating without extra slack. Another common problem is the fan contacting the shroud while it spins.
- Examine the radiator cap to ensure that you’ve got an appropriate seal.
- Use a stethoscope to listen to the engine noises from the top. You’re attempting to hear any clacking or knocking sounds. If you have valve covers, you’ll want to listen there as well, along with the intake manifold’s top. Detecting sounds here can indicate problems with your tappets or hydraulic lifters.
- Use a floor jack to lift your vehicle. Keep two jack stands under the front of the frame, with another two at the rear. Place the stethoscope against the bottom of the engine block and oil pan to hear if there’s rhythmic popping. If there is, you could have a worn piston pin.
- Lower the vehicle. If the sounds came from the engine’s bottom, you’d need to confirm it during this step while locating the cylinder. Use insulated plug wire pliers to remove the wires one at a time from the location. When you hear a change to the sound, you probably have a bad rod bearing there.
- Use a vacuum gauge on the intake manifold hose. If you get any deviations from the reading, you might have a blown head gasket causing the problem. You would also see oil in the coolant or radiator to confirm this problem, along with bluish-white smoke coming out from the pipe.
- Popping from the exhaust manifold indicates a cracked or blown manifold gasket.
- Connect a timing light to your vehicle. Refer to the owner’s manual for the correct timing number in degrees after removing the air intake or cleaner housing. If it is incorrect, you’ll get popping noises from the carburetor.
You can also let the engine warm to a standard operating temperature. Once you reach that level, shut the engine off to examine the coolant reserve. It helps to remove the reservoir cap to listen for popping sounds.
If you hear that noise, it’s an indication that a cylinder pressure release is occurring, which points to a bad head gasket.
Additional Sounds That Could Mean Trouble for Your Vehicle
Although popping during acceleration or right after is not unusual, that description might not be how you’d describe the sound. Since noise interpretation is somewhat objective, here are some additional issues you might encounter when trying to diagnose what is happening with your vehicle.
| Pinging or Knocking: | • When the engine runs, fuel gets ignited in the cylinder. • If a metallic ping or knock occurs, there could be an ignition malfunction. • This problem could indicate worn spark plug wires, a clogged fuel injector, or a bad filter. |
| Banging: | • If you’d describe the sound as more of a “bang” than a “pop,” you often have an air intake or fuel-related problem. • If it happens constantly, the issue could be as simple as a dirty air filter. • When it is intermittent, you might have a clogged fuel filter, ignition wiring issues, or worn spark plugs. |
| Clicking or Ticking: | • You want to hear a clicking sound when fastening your seatbelt. • You don’t want to have this noise coming from your engine! • If that happens, the most common cause is being low on engine oil. • It can also occur if your struts or fuel injectors are worn. |
| Rubbing or Grinding: | • The most common sounds with this issue come from the brakes. • You might hear them when the pedal isn’t engaged because the discs could be stuck in contact. • If you think this problem exists, you’ll see dust collecting around your rims and wheels. • The steering might also pulsate or vibrate whenever you are trying to come to a stop. |
| Rattling: | • If your car makes a rattle, the sound typically comes from underneath the vehicle. • It’s usually due to a loose part, such as a gasket or bracket. • There could also be an issue with the muffler, manifold, or catalytic converter. |
If you hear any of these sounds, it’s often best to take the vehicle to your mechanic for a checkup unless you’re familiar with automotive repair.
How to Solve the Engine Popping Problem
If your only problem is that the engine pops when you accelerate hard and let up on the gas suddenly, you might not need to do anything. This issue occurs with many vehicles because of how fuel gets distributed to create combustion for forward movement.
When you heard the unusual sound, the first step is the check your heads-up display. If the Check Engine warning appears, your onboard computer might activate a mode limiting how much power goes to your drivetrain. Your next stop in this situation would be to a mechanic.
If the popping sounds are muffled or accompanied by a low rumble, pull over somewhere safe to cool the engine. It might take several minutes. Once you can access areas under the hood safely, look for damaged or disconnected wires and hoses.
If you don’t see anything, turn the engine back on to listen for hissing or sucking sounds that would indicate an air leak is happening.
Most problems are a DIY fix. You might need to replace your spark plugs or wires to eliminate the sound. If the fuel filter is the issue, it might be easier to take your car to the mechanic for a replacement.
When everything seems to be in working order, the issue could be with your fuel injectors. If they get clogged, your vehicle won’t send enough gasoline to the engine to perform as it should.
That’s why using an injection cleaning product can resolve the problem.
What Is the Best Fuel Injection Cleaner to Use?
I have a Dodge Journey at home that we use for family trips. It offers an excellent acceleration profile, but it sometimes delivers that dreaded popping sound. That’s when I know it is time to take care of the fuel injectors.
Instead of buying a random product at the closest convenience store, I prefer to stock up on Lucas Fuel Treatment.
This product gives me two benefits.
- It can neutralize the problems with poor-quality fuel so that my engine operates the way it did when we left the dealership with it.
- It cleans the injectors relatively quickly.
I noticed the performance change almost immediately after adding it to my regular maintenance routine. It’s formulated for gasoline and diesel engines, which means I get to use the same product for my Volkswagen.
It won’t negate ethanol damage, but it can help your engine process fuel more efficiently to obtain a better fuel efficiency ratio.
I know some people like to use it with every tank. I tend to go with every other or every third fill-up to maximize its use.
Best of all, Lucas Fuel Treatment stopped the popping noises we heard from the engine!
If you keep hearing a popping sound, it is essential to eliminate the potential issues so that you can address the problem. Once you find the cause, it’s much easier to find the correct resolution!