If you’ve noticed that your engine doesn’t sound like normal, chances are that your spark plugs are damaged. If your spark plugs don’t function properly, there’s no way for the fuel and air mixture to get ignited in the combustion chamber. For years, spark plugs have been critical to the way your engine functions. Spark plugs use the electrical signal sent from the ignition coil to create a spark and this ignites the air fuel mixture inside the combustion chamber. Spark plugs come in different shapes and sizes and in each vehicle requires a different type of spark plug. Spark plugs have a good correlation with your fuel being burned so if you have good spark plugs, you’ll have a better fuel economy.
In order for your spark plugs to function correctly, they need routine service and maintenance so that your engine is kept strong. Its recommended that your spark plugs get changed every 30,000 to 50,000 miles. Depending on the type of vehicle you have, you may not need to get your spark plugs serviced or replaced. For example, vehicles like trucks, SUVs and some newer cars have an advanced ignition system that makes spark plug replacement obsolete. Regardless of if you’ve been servicing your car properly or not, there are some situations where you’ll see signs of a bad of worn out spark plugs. If you notice any of the common signs below, you need to head to the mechanic and get your spark plugs replaced as soon as possible.
Slow Acceleration
The first and most prevalent symptom of a bad spark plug Is the slow acceleration. Any time you notice that your vehicle isn’t accelerating as fast as it was, you should blame your spark plugs first. There are multiple sensors that tell the PCM when to send electrical signals to the spark plugs so they can ignite the air fuel mixture. If your sensors are failing, this could also make it look like it’s the spark plugs that are doing it. The spark plugs are made so that they can produce a hot enough spark to ignite the air-fuel mixture. If the materials of the spark plugs are worn down, the spark plug will no longer be as effective. This loss in performance will show in the acceleration of your vehicle.
When pressing the throttle, if you notice that your car isn’t pushing as much as it used to, or the acceleration is slower than before, chances are you have a bad spark plug in your hand. If this is the case, you should go to your nearest workshop and get a mechanic to get your spark plugs checked out and potentially replaced.
Engine Misfire
Another symptom of bad spark plug is an engine misfire. If you experience a misfire, chances are you experience it due to a bad spark plug. If the spark plugs aren’t producing a hot enough spark to ignite the air-fuel mixture in the chambers, this can cause a misfire. A misfire is when the cylinders in the chambers aren’t firing correctly, therefore, you’ll feel a loss of performance in your engine and it could lead to long term damage of your engine. If 1 of the 4 cylinders failed to fire correctly in the chambers, your vehicle will lose 25% of it’s power. This goes back to the slow acceleration – engine misfires are a cause of slow acceleration and bad spark plugs. Usually when your engine misfires, you’ll feel a jerk within your car. Another way to tell if your engine is misfiring is if the engine runs rough at idle.
Poor Fuel Economy
If your spark plugs are healthy and functioning correctly, then fuel should be burned efficiently in the combustion chambers. When this happens, it means that sensors are providing the right signals to the PCM therefore the correct air-fuel ratio is made and ignited. This will give your vehicle a good fuel economy. If your spark plugs are failing, chances are the gap between the spark plug and electrodes are too close or too far apart. If your spark plugs ever get examined, the first thing the mechanic will do is check how close the spark plug is to the electrode – what happens in most cases is that the gap between the two is adjusted rather than the spark plugs getting replaced. If more fuel is being ignited by your spark plug, chances are they’re worn out.
Check Engine Light
If the check engine red or yellow light illuminate on your dashboard, it could be attributed to the spark plugs. Your car has a computer that checks other systems like the emissions control system. If it sees that the system isn’t able to regulate or maintain a problem in the vehicle without any assistance, the check engine light will come on. If the spark plugs aren’t performing as they should, the PCM will recognize this and cause the check engine light to come on. If you want to diagnose why the check engine light came on, you can use an OBD2 scanner (View on Amazon) to diagnose the error codes the vehicles computer is giving you. If you see that the error code is related to the spark plugs, then you’ll need to get them checked out in your local workshop.
Engine Hesitating
If you try and accelerate and you notice that the engine is hesitating, it could be down to your spark plugs. If the engine isn’t responding how you want it, it could be a sign that your engine has lost a lot of power. If more air is being used in the air-fuel mixture in the combustion chamber, this will cause a delay in the power that’s delivered to the engine. If you notice that your car doesn’t respond when you try and accelerate, you should get your spark plugs checked out.
Rough Idle
The O2 sensors are a set of sensors that regulate how much air the vehicles receiving for the air-fuel mixture. If bad spark plugs cause the engine to misfire, unburnt fuel can trick the O2 sensors into making a lean mixture. This can make your engine sound rough when idling. Your vehicle may start to vibrate, or you may here a jittery sound. If you can feel the engine misfiring when the vehicles idle, then it could indicate a problem with your spark plugs.
Hard to Start
If your vehicle is hard to start, it could be a sign that your spark plugs are worn. Your engines ignition system has a lot of components that must work flawlessly together for the engine to have a good start. If one of these components are not working properly, for example the spark plugs, then it can disrupt the process and cause the engine to have a bad start. If you notice that your car has trouble starting, it could be due to the ignition of the air fuel mixture being poor. If the mixture can’t be ignited properly, this can lead to bad starts.
Engine Knocking
If your engine is misfiring, knocking is an extreme case of this. If you notice your engine knocking severely, chances are its due to bad spark plugs. The knocking sound is a classic sign that your spark plugs are in trouble so if you hear this, you should narrow it down to the spark plugs. If symptoms become audible, you should be working because the risk of damage within the engine increases.
There are a few components that could be damaged just by the engine knocking. The piston heads are the first components that could be affected badly by the engine knocking. If the knocking is intense, it could damage the piston head. Another thing it could damage is the piston compression rings – they are subdued to a lot of damage when the engine is knocking although they’re not as bad as broken piston head. The cylinder head along with the cylinder head valve could become damaged when the engine is knocking. The cylinder head valves could melt due to the high temperature that’s caused by the increased pressure in the engine.
Increase Emissions
If the spark plugs are working properly, then you should expect bad emissions along with the car. Bad emissions occur when the car is burning off more fuel than it needs to – this can lead to you failing emissions tests and this can put you in trouble. If you notice any thick white or blue colored smoke coming from the engine, this could be a sign that your car is burning off more fuel that it needs to. This fuel excess fuel that’s being burnt can also leak into the oil pan and a loss in oil quality can cause further problems with your car.
Gas Smell from Exhaust
If you can smell extra gas in your exhaust pipe, this can be an indicator that there’s unburnt fuel leaking out the combustion chamber. This could end up with fuel leaking out of the exhaust system also known as a backfire. If the spark plugs aren’t able to ignite the fuel properly, this can lead to excess fuel coming out of the exhaust chamber. In this case, you’ll need to get your spark plugs looked at or replaced.
How to Fix Bad Spark Plugs
If your spark plugs aren’t functioning properly, it means that the combustion process in the engine is going to be affected. Making sure that the spark plugs are maintained will stop them from going bad and it’ll allow the combustion process to start working properly again. If the spark plugs are bad, this can affect the engine negatively and this can cause it to blow in the long term. The last thing you want to experience is a blown engine because the cost to fix it is very expensive.
If you want to avoid spark plug problems or other issues and save $100s of dollars that you’ll spend at the auto repair shop, you’ll need to service your vehicle often – you can use our mechanic-rated Auto Maintenance and Repair Manual to do this. It’s basically what mechanics use to go through your vehicle to check if there are any problems that need fixing. As soon as they notice the most minor problem, they’ll ask you to fork out some money even though it’s a problem you can fix yourself in minutes – the manual will teach you how to maintain your vehicle every few thousand miles and it’ll teach you how to fix minor problems that mechanics will ask you to pay for; saving you money in the long run.
A lot of our readers have the Auto Maintenance and Repair Manual printed on their garage wall and 92% of them haven’t visited the auto repair shop in the last year because they know what to do to avoid problems. All it takes is giving your vehicle a little attention every few thousand miles and you’ll never spend money at the workshop again.
What Do Bad Spark Plugs Look Like?
If you’ve received some symptoms, but you want to be sure that your spark plugs are failing, you can visually inspect them. With bad spark plugs, you’ll notice a few things and they look a lot better than functioning spark plugs.
Wet or Dry Oily deposits – if you touch the spark plugs and feel a wet or oily texture, it could be caused by a leaking head gasket. It could also be cause by the piston rings leaking oil onto the spark plugs. This usually happens when the fuel injector is injecting too much fuel into the air-fuel mixture. If you notice that there’s a wet or oily substances on the spark plugs, you should get them checked out.
Dark in Color – if the spark plugs are dark in color and covered in wet or dry deposits, chances are that the engine is using too much fuel – there shouldn’t be any dark, wet or dry deposits on the spark plug unless this can be an indicator that fuel has leaked onto the spark plugs. The spark plugs may not be able to ignite the fuel in the air-fuel mixture properly, therefore, the excess fuel leaks onto the spark plugs. This can also be caused by a vacuum leak or low cylinder compression.
Glazed Electrode Tip – if you notice that the electrode tip is glazed, this can be caused by a spark plug that’s continuously over heated – this could be due to a lean air-fuel mixture. It can also happen when the spark plug is loose within the engine.
What to do If You Have Bad Spark Plugs
If you’ve experience symptoms of a bad spark plug, inspected them, and it’s pretty obvious they’re failing or damaged, there are a few more thing you can do. It’s pretty clear that your spark plugs are bad, but you can narrow it down or get it checked out.
OBD2 Scanner
The first thing you can do is to inspect the spark plugs with an OBD2 scanner. When there’s a problem with your spark plugs, it will send off error codes when scanned with an OBD2 scanner. A professional OBD2 scanner tool (View on Amazon) will allow you to look up the error code on the scanner, whilst a standard OBD2 scanner tool will force you to look up the error codes meaning in your car’s manual.
You need to connect the scanner to the connector under the setting wheel. This is where most connectors are located and where you’re likely to find the connector. Once connected, you need to switch on your car’s ignition and make sure that the devices are connected, e.g. the radio. Then, press the red button on the OBD2 scanner so that it can start to scan your engine’s control unit for any problems. If you have a professional OBD2 scanner, you’ll be able to check if the error codes relate to bad spark plugs are not. If you have a standard one, you’ll have to write down the error codes and check what they mean using your service manual or searching it up on the web.
Replace all the Spark Plugs or Get them Inspected
If you know for sure at this point that there’s a problem with your spark plugs, you can go to the mechanic and get your spark plugs replaced. It’s not advisable that they’re completely replaced – sometimes they just need adjusting. But, if you’ve had your car for some time and it’s causing a lot of problems, the mechanic might have to replace them. The replacement isn’t too expensive, but you’ll be paying for an inspection, the actual spark plugs themselves, and the replacement of them which call all come up to about $300 depending on the vehicle you have.