Misfiring Engine – What Is It and What Causes It?

Have you noticed that your car’s acceleration is slowed or can completely lose power? Chances are you’re experiencing a misfiring engine.

Whatever the cause, engine misfires need to be dealt with as soon as you can manage. Some of the common causes are fouled spark plugs, fuel injectors, clogged fuel injectors, or malfunctioning oxygen sensors.

In any case, a misfire can mess with your emissions, which could lead to a ticket. In addition, engine misfires can damage the other parts of your engine and lead to a bigger maintenance bill.

Engine Misfiring: What is It?

Engine misfiring is a common problem that can turn dangerous if left untreated. But these malfunctions often sound a lot worse than they actually are. Put simply, an engine misfire is a malfunction of the components needed for a cylinder to fire.

engine misfire

Sometimes this can be a result of incorrect ignition timing. Or it might be wear and tear on your valve spring or a vacuum leak. Other possible reasons include there not being oxygen for burning the fuel or a spark plug error.

Is Engine Misfiring Dangerous?

Driving with a misfiring engine can be dangerous for several reasons.

For starters, it can mess with your exhaust and turn it black. This is a hazard for both you and other drivers on the road.

Alternatively, engine misfires can cause you to lose power since they damage the other parts of the engine. Losing power while driving is incredibly dangerous as it takes control of your vehicle away. Furthermore, losing power may cause other parts of your engine to wear down quicker than normal.

There’s never a good time to drive with a misfiring engine. It’s recommended that you take your car into a mechanic to have your engine inspected right away. If you do need to drive your car to the auto shop, go slowly or consider hiring a towing company to make the trip for you.

How do You Know if Your Engine is Misfiring?

It’s not very hard to tell if your engine is misfiring. There are several major signals that you should pick up on as you drive your vehicle.

One of the biggest signs of a misfire is a loss of about 25% of your engine’s overall power. Basically, you won’t be able to drive as fast or as far if your engine is misfiring. This can also be accompanied by shaking or vibrations that you should feel in your steering wheel.

Misfiring engines may also be very difficult to start. Sometimes, this manifests as stalling whenever your car goes into an idle state, such as when you are waiting at a stoplight. If you have a cantankerous engine that doesn’t start consistently, it may be due to a misfire.

Of course, the telltale “bang” sound that accompanies many misfires is another surefire sign. While not all misfires have a gunshot-like sound accompany them, most do.

Finally, many modern vehicles’ “check engine” lights will come on when a misfire occurs. Keep an eye on this light your dashboard to stay abreast of any potential engine problems.

Read more: Car Engine: What It Is and How Does Car Engine Work?

How do you Fix a Misfiring Engine?

Thankfully, fixing a misfiring engine doesn’t have to be too complicated. You should always start with your “check engine” light and see what code it is displaying. Taking this code to an auto repair shop should allow you to pinpoint whether or not you are suffering from a real misfire.

Alternatively, you can buy a code reader and scan this information for yourself. It’s a good choice if you already have some auto mechanic experience. This tool can remove the code from the dashboard, as well.

You can perform the repairs you need yourself if you have some auto mechanical know-how already. You’ll need to check the various possible causes of your engine misfire.

Misfiring Engine Causes

Spark Plugs

Check the spark plugs first, as these are one of the most common causes. Because spark plugs are so cheap, it’s often a good idea to swap them out to be sure they aren’t the problem. At the same time, you can replace the spark plug wire since it might be causing the misfire as well.

One thing to note is it’s good to remember the mileage on the spark plugs and change them periodically.

How to deal with engine misfiring

Vacuum Leaks

Next, pop open the hood of your car and look for signs of a vacuum leak. Turn the engine on and listen for a high hissing noise. If you hear that, it’s a good sign that a vacuum leak is your issue.

To fix this, pinpoint the leak using a spray bottle filled with liquid dish soap. Spray the dish soap along both vacuum lines of your engine, as well as the manifold intake gasket. Don’t forget the PCV valve, too.

If you see bubbles, that’s where the crack or vacuum leak is. You can replace whatever damaged section you find.

Ignition Coil

Next, check your ignition coil, particularly if the engine misfire is accompanied by stalling or backfire sounds. This is most common on vehicles over a few decades old. Ignition coils are usually at the end of your spark plug wires.

Replacing your ignition coils shouldn’t be too expensive. The parts can be affordably purchased at most auto body shops. Be sure to pick out the correct ignition coil for your make and model of vehicle.

Ignition System

Spark plugs, control modules, crankshaft position sensors, and coil packs are all parts of the ignition system. If one of them is not working properly, it’s vital to replace or fix those parts.

Air-Fuel Mixture

One of the reasons for misfires is the air-fuel mixture which prevents the spark plug from starting the car. To pinpoint what stops the combustion chamber from delivering the fuel, you need to look at problems such as vacuum leaks or a failing fuel injector.

Electrical Circuits

Modern vehicles tend to have sensors and ignition coil packs connected through the electrical circuits. If the circuits are damaged, chances are your engine management system doesn’t receive the correct data, and misfires happen.

Other Mechanical Problems That Cause Engine Misfires

Finally, you might be suffering from a mechanical misfire. You’ll have to check the major mechanical parts of your engine to ensure that everything is operating smoothly.

Examine the timing chain and make sure it hasn’t been stretched out too much from regular wear and tear. You can use a timing light while your engine is idling to see if your timing chain is stretched out. You’ll need to replace it if this is the case.

Check the intake manifold for a vacuum leak, as well. You can use the soapy spray bottle water technique that we described above to locate this leak if it exists.

Another issue worth checking is whether the cylinder is clogging properly. In case of an air gap, misfire occurs quite often. To prevent it from happening, the cylinders must compress the air-fuel mixture efficiently, but with a gap, it may cause engine problems.

Is a Misfiring Cylinder Expensive to Fix?

It depends on what work is needed to repair your engine. Many auto mechanic shops charge a flat fee for all misfiring cylinder jobs. Others will charge you for specific work or part replacements.

It’s often cheaper to make engine misfire repairs yourself if you can successfully identify the cause. However, make sure you know what you’re doing before attempting repairs. Making the problem worse could cost you more money in the long run.

Engine misfires repaired by auto mechanic shops run between $80 and $300 on average.

Frequently Asked Questions

How much does it cost to fix a misfiring cylinder?

The price for repairing or replacing the misfiring cylinder can range from an affordable $100 to a shocking $1,000. The final expense will highly depend on the cause of a misfire. While faulty spark plugs may cost up to $300, broken pistol rings’ starting fee is $1,500 and up.

Is it safe to drive with a misfire?

It’s not advised to drive your car while it’s experiencing misfires, even when those happen momentarily. You may be starting your car to go to work or driving in the middle of nowhere when your car’s engine happens to fail you.
If a misfire happens once, it’s best not to ignore it. Otherwise, your engine power will decrease, and your car will be consuming more fuel than usual. In addition, as misfires continue to happen, vital parts of your vehicle will deteriorate faster.
Hence, it only makes sense to service your car and save money in the long run.

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