How to Tell if a Spark Plug is Misfiring- 6 Signs

How to Tell if a Spark Plug is MisfiringThe part that spark plugs play to ensure your engine's proper functioning is truly valuable. However, there could be conditions that may invite unwanted events and erupt in another way. That's probably not good for the health of your vehicle.

One of such bad events is known as misfiring. This is something you need to look at seriously. And so, let's find out how to tell if a spark plug is misfiring with some common signs.

How to Tell if a Spark Plug is Misfiring & Causing Trouble

Signs that serve as a warning are of course not pleasant news. However, these signs let you do something about the problem within and so, it's not that bad truly. Make the good use of these signs by taking them seriously and considering proper steps afterward.

That way you'll be able to maintain a good condition of the overall engine system. I'll talk about some common indications that will help you but before that let's clear about what exactly misfire is”¦

Engine Misfire?

The four-stroke combustion engine must be in a pleasing condition to function actions in accurate order timely to ensure proper fuel burning and power production. With piston traveling downwards, the combustion chamber welcomes a guest of precise air-fuel combination.

And that happens while intake valves open up. Once this valve shuts down, the mixture starts getting compressing. And so, the piston moves its way in opposite direction which means upward.

The spark plug uses air-fuel mixture for ignition on a power strike. And this allows for precision increment at the cylinder. This process triggers piston to fall down rapidly and at the same time turns crankshaft as well.

On exhaust stroke, the valve opens up and cylinder expels burnt gasses. This cycle keeps on repeating. The necessary components may have some sort of problem that could lead to misfire. It could also be a system related to mechanical components problems. For example, the cylinder itself.

Improper timing or failed process causing cylinders may be a reason for engine misfire. A wrong air-fuel ratio can lead to failed combustion. Sometimes it may cause knock or premature detonation.

is Engine Misfire

Also Read: Best Spark Plug Gap Tool| Top Picks and Reviews

First Sign ”“ A Sluggish Car.

The very first and primary reason for a misbehaving vehicle is its poor acceleration performance due to ignition system. Today's modern engines are designed smartly. They have more than a few sensors in use.

And so, it can tell the onboard computer as well as ignition system about electric pulse transferring that fires spark plug. This means a faulty sensor can also be a reason. Worn our spark plug is the most common problem, however.

There are multiple materials inside the spark plug to create spark hot enough. And that leads to igniting the mixture of air and fuel. Due to worn-out materials, the effectivity of spark plugs may get lost. And so, you face acceleration issues with the vehicle.

As soon as the vehicle starts behaving sluggishly with poor acceleration performance, you should be aware of a faulty spark plug. And go for a replacement quickly.

Contacting a professional for complete inspection is recommended here. Since there can be other factors responsible combinedly. Such as bad fuel filters, problematic oxygen sensors, and even clogged fuel injectors.

Second Sign ”“ Sudden Increase in Fuel Consumption.

During the combustion cycle, spark plug helps in burning fuel if it's in a fully functioning condition. This means you are supposed to enjoy better than average fuel economy. Sometimes the gap between spark plug gets too close or far apart. As a result, it leads to improper functioning.

In such circumstances, experts get the plug out and fix this problematic gap. They bring it to factory settings if a replacement is not necessary. So, if you are witnessing a high fuel consumption with the vehicle, there can be a problem with spark plug. And it can cause misfiring if you don't take the signs seriously instantly.

Third Sign – Irregular Stumbling & Crackling Noise.

Another common signal is facing irregular stumbling with your vehicle. It can also show a cracking noise. Since the misfire happens mostly because of ignition system faultiness, there's a high chance of sensor malfunction.

And it could be because of a damaged wire in a spark plug. If you’re noticing the weird stumbling and noise, it's probably a huge sign to not ignore. It can lead to increased exhaust emissions. And that will result in decreasing engine power. As a result, fuel economy will also drop dramatically.

Fourth Sign ”“ Wavering Engine.

Have you noticed a weird hesitation of the engine while trying to accelerate? If that's the scenario then engine is not answering to user in a correct way. The surge in power starts to be evident and this leads to slowing down.

The engine is probably gasping more air than required for combustion process. And this is causing a delay in the delivery of power. This joint hesitation and surging can be a huge sign that there's a problem with the spark plug.

Fifth Sign ”“ Rough Sound When Inactive.

When you leave the vehicle idle it could react by making a rough sound as an indication. Due to the encompassing and jittery sort of sound, you'll notice a vibration in your vehicle as well. This is a great signal that the spark plug needs proper handling. Usually, it's the case of cylinder misfiring noticeable while in idle.

Sixth Sign ”“ Problematic Starting.

Do you notice an improper behavior when trying to start the vehicle? This is a clear sign of worn-out spark plug usually. The multiple components of an engine's ignition system maybe not working cohesively.

And due to this, there can be a problem resulting in improper function. Once you start to notice that your car, truck or SUV is showing weird reaction when starting, contact a certified mechanic quickly. It could be also due to other reasons than just a damaged spark plug. The professional should be able to tell you after an inspection.

A Scan Tool Can Tell!

JEGS 8977 OBD II Scan Tool Works w/Most 1996 & Newer VehiclesIf you own a vehicle that uses the OBD II Scan Tool 1996 or newer version, then a scan tell can be helpful for detecting misfire. This system can identify a misfire that exceeds the normal limit. Once it figures out the condition, check engine light illuminates and a P-code is set.

This corresponds to the cylinder's misfiring. By referring to the final number of P0300 series code, you can tell which cylinder is facing misfire. For example, cylinder number 4 has a misfiring incident of you witness the code P0304. If there's a problem due to bad injector, then the scan tool should work with P0200 series code.

The P0300 code refers that the misfire is randomly moving around from one cylinder to another. This could be due to an upsetting air and fuel mixture. For example, leaky EGR valve or a vacuum leak. Only an expert can tell you in detail about the underlying cause, however.

Ending Note

And that's how to tell if a spark plug is misfiring in your vehicle. Now, once you figure out the signals, don't drive for any long distances. With a catalytic converter, the emission may be reduced. However, there's a chance of damaging other sensors. Just bring the car to a nearby mechanic workshop to fix it. You should try to put as least as possible load on the engine.

About Jeremy

Hello! My name is Jeremy Bloomberg. I have been passionate about carpentry and DIY. Over the years, my passion slowly turned into expertise and wider knowledge about electronics. I’ve been involved in numerous projects, both professional and personal. I want to share all I have learned with you. Welcome!

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