SYMPTOMS OF BAD SPARK PLUGS
PURPOSE
The purpose of spark plugs is in the name. Spark plugs create a spark inside the combustion chamber to ignite the air/fuel ratio.
LOCATION
Spark plugs will be threaded into the engine underneath the ignition coils in a coil-on-plug ignition system. If you have a four-cylinder engine they will typically be located at the top as shown in the image attached. If you have a 6 or 8-cylinder engine, they could be located on each side of the engine (left/right or front/back).
symptoms
engine light
The first symptom of bad spark plugs is having a check engine light on. More specifically you can have a blinking engine light when there is a misfire occurring. If any of these misfire codes pop up P0300 - P0312, your vehicle could have bad spark plugs.
Ensure you can access your car's diagnostic codes by acquiring an OBD2 scanner here.
It’s important to remember that you can still have faulty spark plugs without the check engine light on. So keep reading this article to learn more symptoms of bad spark plugs.
ROUGH IDLE
The second symptom of malfunctioned spark plugs is a rough idle. If you feel your car shaking or vibrating while stationary with the engine running, it could be caused by bad spark plugs.
poor Gas mileage
The third symptom of bad spark plugs is poor gas mileage. Faulty spark plugs won’t be able to produce a perfect spark. As a result, the MPG (miles per gallon) in your car will drop, leading to you going to the gas station more often and spending more money.
lack of acceleration
The fourth symptom of faulty spark plugs is a lack of acceleration. If you’re trying to increase speed but notice the vehicle doesn’t move as fast as it used to, it could be caused by worn spark plugs. For example, if your vehicle has 8 spark plugs, and 4 of them fail, you won’t have as much power to accelerate. Imagine, 8 people trying to lift a heavy piece of equipment, and then you lose 4, your manpower will decrease by half and your guys will get much more tired. This is exactly what happens to the engine with defective spark plugs and why you may notice a loss of power.
slow crank but no start
The fifth symptom of worn spark plugs is your car slow cranking with no start. This symptom is not so common but it’s still possible. If 3 out of 4 spark plugs don’t create a spark to ignite the air/fuel ratio, your vehicle is going to have a hard time turning over the engine. In order for your car to start, all spark plugs need to be functioning properly to start combustion and turn the engine.
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