- The car feels like it is shaking, unbalanced or rough when driving.
- The car check engine light comes on.
- Acceleration is sluggish, or sometimes, rough.
- Sounds from the engine, such as clanking, sputtering, popping, etc.
- Black exhaust smoke comes from the car.
- Rough or clunky idling.
- Noticeable lack of power or underperformance.
- Sometimes, the smell of gasoline, oil, or coolant is noticeable.
- Engine stalling.
- Poor gas mileage.
It's worth noting that many of these symptoms can indicate other problems. If you only experience one item on the list, it may not be a misfire but something else. However, if you suspect a misfire for any reason, it is a serious problem. Make sure it is properly fixed or take it to a qualified mechanic.
Read more to learn all about engine misfires - what it is, and how to identify the symptoms. Learn how to fix it and why you should never ignore an engine that is misfiring.
What Is A Misfire?
A car's engine relies on combustion - there must be fuel, oxygen, and a spark to ignite them. A misfire occurs when any of these three components are not working in sync - the spark is not present or too late. The fuel/air ratio is incorrect, or the fuel is plugged in some way. Loss of compression in the engine can also cause a misfire, as the fuel/air mixture fails to "reach" the spark.
This can occur in any of the vehicle's cylinders. When one cylinder stops working, but the rest continue, this causes the sensation of a "misfire." Every time that missing cylinder should be "working," you may feel the loss of power, experience symptoms, or hear sounds from the engine.
In many cases, a misfire is caused by something relatively simple - a bad spark plug or coil, for example. However, there's a wide range of possible reasons for a misfire. If you can't narrow down the cause yourself, seek the help of a professional mechanic. It's a complicated issue, and it can be challenging to diagnose.
Signs Of A Misfire
The most obvious sign of a misfire is that the car itself feels off-balanced or shaky when driving. Since one cylinder isn't functioning, you'll notice that off-balanced sensation every time it should be contributing power and isn't. It can be like a shimmy or a shudder through the vehicle. This is also the reason for low power or underperformance - the car has lost the force of an entire cylinder, after all.
Rough idling often indicates that the problem is the fuel, somehow. However, this is still a broad area - it can be a fuel filter, pump, or more.
Sluggish acceleration can mean that your car is in "limp mode." This tactic in some car models reduces the acceleration to prevent accidents when there's an evident problem with the vehicle.
Engine noises, smells, and black exhaust all show something wrong with the fuel/air ratio or how the fuel is being burnt. This can indicate compression issues or a problem with the fuel.
One of the best indicators of a misfire is the check engine light. While it's true that light could come on for many reasons, there's one clear sign of a misfire. In a misfire, the light often flashes on and off whenever the faulty cylinder misses. Most other engine problems are consistent - the light comes on and stays.
How Do You Fix A Misfire?
The first step is to determine what is causing the misfire. With any luck, some error codes may pop up when you check out the car. These may offer a clue as to the reason for the misfire.
For example, sometimes a misfire is due to inadequate fuel or air getting through the engine. Codes can help identify the root problem. A faulty coil that's preventing the spark plug from igniting may also show an error code.
If the codes don't help, try checking your spark plugs. If you can tell which cylinder is misfiring, check that cylinder's spark plug. Disconnect the plug wire and use a socket to remove the plug. Examine it for signs of wear, which may help identify the underlying problem. The gap between the plug and the base is sometimes the problem - this affects the air/fuel ratio (check your vehicle's manual for the proper gap).
You can also test the fuel injectors by disconnecting one at a time. If the engine begins to run worse, that fuel injector was working. Reconnect it and try another. If you find one that shows no change in the engine, connected or not, you've found the problem. Replace the fuel injector. You can also try to clean it with a carb cleaner, though that doesn't always work. Read more about using fuel injector cleaners here.
Other issues can cause a misfire. For example, a bad head gasket, fuel filter, or fuel pump can all be the culprit. However, for problems such as these, the solutions get a bit more complicated. It's typically best to let a professional mechanic diagnose and deal with it.
Can Misfires Damage Your Engine?
The cylinders are, in short, what powers your car. If one is misfiring, it can cause a loss of power to the vehicle, thanks to the missing cylinder. For example, losing one cylinder in a car that only has four cylinders is the same as giving up 25% of the car's power.
This isn't safe for the car and can cause more severe damage. If the vehicle were designed to run this way, it wouldn't require all those cylinders in the first place. None of them are "optional," and losing the power of one is a serious problem.
If you have a misfiring cylinder, you can lose power over other cylinders as well. If you're driving when this occurs, it can cause a car accident. In the case of a misfire, always take it seriously. When you can't find the cause yourself, have your engine checked by a qualified professional.
Can A Misfire Go Away On Its Own?
It's rare for a misfire to clear up on its own. The only possible reason a misfire could be considered "fixed" is if the only problem was bad gas, and putting in new gas has solved it.
More likely, even if you believe the misfire is a thing of the past, it will come back sooner or later. Sometimes, the issue may pop up sporadically, leading you to ignore it for a while. You can act as though it didn't happen - out of sight is out of mind.
The big problem with this is that the issues may have grown when it does come back. Typically, a misfire starts as something simple - a bad spark plug or coil, for example. However, when ignored, it tends to snowball into bigger problems like a failed head gasket. For a relatively low cost, what could have been easily fixed by yourself now requires a mechanic and some serious bills.
How Long Can You Drive With A Misfire?
You really shouldn't drive the car any further than you need to. It's not necessary to pull over immediately and have it towed to a garage. But don't continue running errands and roaming about. It's simply not safe to continue driving any further than you need.
If another cylinder goes out while you're driving, it can cause an accident. It's also bad for the car - it can damage pistons, cylinders, and other engine parts.
There are a variety of signs that your car is experiencing a misfire. One of the most common is a lack of power in the car, which may cause a shimmy, shudder, or off-balanced sensation when driving. A check engine light that flashes on and off frequently is also an indicator. Rough acceleration or idling, strange noises and smells, and engine stalling may also occur.
If you believe that your car is misfiring, it's important to address it immediately to avoid further damage to the vehicle. Driving a car that experiences misfiring can also be dangerous. It can be caused by a variety of problems and is sometimes difficult to diagnose. If you can't figure out the root of the issue, consult a mechanic for help.