Engine Misfires – Meaning, Symptoms & Possible Causes

Engine Misfires

Do not think that misfiring is peculiar to your car engine as misfires remain one of the common issues with gas engines these days.

A lot of things could be responsible for your engine misfiring and sometimes you might be confused as to what exactly is causing the issue.

If that is the case, then you are at the right page. What we will be discussing in this article are the various things that can cause engine misfire and the symptoms to look out for.

What is a Misfire?

In case you are not sure yet as to what a misfire really is, this section is for you. We are going to paint a very vivid picture of how a four stroke engine operates so that you will get to really understand what a misfire is.

So when your engine is running, your pistons are pushed down while the crankshaft is spinning all in the cylinder.

Now for a four stroke engine, the engine operates in four steps, guess now you understand the name.

The four steps are as follows;

a. First, the piston goes down and this allows the cylinder to be filled with air-fuel mixture from the intake.
b. After that, the piston goes up and the air-fuel mixture is compressed to a high pressure.
c. Next the ignition from the spark plug lights up the air-fuel mixture. The explosion from this pushes the piston down and the crankshaft will start to spin.
d. Finally, the piston will go up and the burned air-fuel mixture will be gotten rid of through the exhaust pipe.

That is the process with a four stroke engine which is what most modern cars come with.

So when the process is interrupted or not going as smoothly as it should, or a stage is missed then you have an engine misfire.

Now you should understand why low compression, wrong timing of the inlet and outlet of air-fuel mixture, too lean or too rich air-fuel mixture and a faulty ignition spark can lead to car engine misfire.

Let’s take a look at the most common symptoms of car engine misfires.

Common Symptoms of Car Engine Misfires

Rough Acceleration

Rough acceleration is one of the top symptoms of car engine misfire. It could be in the form of a light or strong jerk from the engine.

You are more likely to observe misfires when on high speed, high gears and low RPM. The misfires would often happen when there is much load on the engine for instance when you are on high speed.

Slow Acceleration

We already mentioned rough acceleration as a symptom of car engine misfire, and another symptom that has to do with acceleration is slow acceleration.

Engine misfires can result in slow acceleration and can even throw your car into limp mode.

If this is the case, your car will not rev over 3500 rpm’s and the boost pressure from the turbocharger will be turned off.

Rough Idle

You can also notice car engine misfire when on idle. What happens is that your engine sensors get the wrong values which results in the air-fuel mixture getting muddled.

In such a situation you will have a rough idle and in some cases, the engine can even go off while on idle.

It is very easy for the car engine to pick up minute air-fuel mixture problems while on idle, so it won’t be a surprise if that is the area that draws your attention to the misfires.

Difference in Engine Sound

As a driver you should know when your car engine is not sounding okay or like usual and if that happens, check it out. This is another symptom of car engine misfire.

Different engines have different sounds for instance V8 engines sound different from four-cylinder engines and four cylinder engines sound different from three-cylinder engines.

You have to be conversant with your car engine sound so that you will know when it is not sounding right.

Check Engine Light

When your car’s Engine Control Unit receives information that something is not right with the engine, it will notify you through your check engine warning light. Engine misfire is one of the issues that can result in your check engine light coming on.

Most modern cars are fitted with this system to help with identifying issues that crop up in the car engine so that they can be handled as soon as possible.

When your attention is drawn to such issues through your check engine light coming on, it is left for you to take the proper cause of action which is to check the codes by using a diagnostic scanner. You can also get a professional to handle it for you if you can’t do it by yourself.

For instance, if engine misfire is the issue with your car engine, and your ECU has picked it up, it is not unusual for your check engine light to come on. So when you have done the scanning and identified the issue, you then proceed to get it fixed and you are good to go.


The various parts of a car engine are meant to be properly aligned so that they can function properly. There are various balance axles in place to ensure that everything is well balanced, keeping vibrations to the barest minimum.

So, in a situation where one or more cylinder is not firing as it should, it will result in the engine not being aligned properly. This unbalance can result in heavy vibrations in your cabin when you are driving or when the car is at idle.

7 Top Reasons for Car Engine Misfires

Now that we are done discussing the symptoms of a car engine misfire, the question that may be top most on your mind right now will be but what exactly is the cause of this engine fire.

There are different things that can result in your car engine misfiring and that is what we are going to be discussing in this section of the article.

Bad Ignition Coil or Distributor

Bad ignition coil for modern cars or bad distributor if your car is an older one is one of the very common causes of engine misfires.

For some cars each spark plug will have their own separate ignition coil, while in some other cars there is an ignition coil connecting to the spark plugs through a a sparking cable.

Older car models come with a distributor but there are some times when they will also be fitted with an ignition coil.

Now back to the issue of the misfires, you can unplug each ignition coil if yours are separate so that you will be able to decide if any of the cylinders is faulty.

If you discover that there is a cylinder that is not responding then just change it.

Injector Problem

Issues with the injector were more rampant about five years ago. A bad fuel injector can result in engine misfires and sometimes they can be hard to detect if they are not flow tested.

Fortunately, issues with the Injector are not a common occurrence with newer cars. So if you have a newer car your injector shouldn’t be the first place you take a look at when you notice a misfire. But you can still take a look at it just to be very sure.

Faulty Spark Plug

Another major reason for car engine misfire is faulty spark plugs. In case you don’t know spark plugs are responsible for powering up your cylinders and in a situation where they’ve gotten worn out or corroded they won’t function as they should and that can result in misfires.

You will be glad to know that spark plugs are actually not expensive and they are not hard or complicated to replace.

If you have not changed your spark plugs in a long while then take a look at them, as they are probably due for a change.

Faulty Air-fuel Mixture

Another factor that could also be responsible for car engine misfires is a wrong air-fuel mixture.

There are various sensors that can make your car have a wrong air-fuel mixture. They include O2 Sensor, Coolant Temperature sensor, MAF sensor amongst others.

Low Fuel Pressure

Some things that could be responsible for Low fuel pressure include a bad fuel pressure regulator, a clogged fuel filter or a faulty fuel pump. When these factors result in low fuel pressure, your engine will have a lean mixture and this can cause misfires on your cylinders.

If your attention is drawn to misfires on all cylinders, then the issue is more likely to be with your fuel pressure.

Intake Manifold Gasket Leaks

Intake manifold gasket leaks can occur close to the cylinder heads and are usual with regards to spark plugs.

Older cars that do not have steel gaskets for the intake get to experience this issue more.

If your car is an older model, this could probably be the reason and you will do well to take a look at it.

For newer cars models there could be other signs of leaks around the intake. One of the things you should check for is broken vacuum hoses.

Low Compression

So you noticed that your car engine is misfiring and you have checked everything that could possibly be the issue yet you have not known the cause, it could then be that your engine has low compression.

For instance, a bad timing belt adjustment can result in low compression and this will then cause your car engine to misfire. If you recently changed your timing belt, you should check to be sure that it was properly installed.

In this article, we have explained what misfires are, discussed the symptoms and have taken a look at its probable causes. We have no doubt that you now really understand car engine misfires are all about.