Cars won’t run forever. Eventually, even the best vehicle will feel a bit under the weather. While some car engine problems will be simply catastrophic, most will be minor, thankfully – including issues like bad or dirty spark plugs.
But how do you know if you need new spark plugs? Once you understand the usual signs of symptoms of a fouled spark plug in older vehicles, it’s much easier (and affordable!) to diagnose and fix the problem. Here are the 7 most common red flags telling you to check under the hood before those failing spark plugs fail completely.
7. Rough Idling
If you turn your car on and let it sit, do you feel the vehicle shaking or hear the engine sputtering? This can be caused by spark plugs forcing your engine’s cylinders to misfire (see sign #6 below). Rough idling can also be a symptom of dirty spark plugs that need to be cleaned, as well as recurring missed maintenance and oil changes.
6. Engine Misfires
A misfiring engine is a fairly common sign you need new spark plugs, though it’s not the only reason. For an engine to misfire, one of three basic problems exists:
- Your engine isn’t getting enough fuel
- Your engine isn’t getting enough oxygen to burn the fuel
- Your engine isn’t receiving a spark to ignite the oxygen to burn the fuel
The latter problem is often called a “spark misfire,” and it’s related to faulty spark plugs or bad spark plug wires interrupting the combustion process. It’s a good idea to have someone knowledgeable check the wiring and the gap (using a spark plug gap tool) to see if there are any issues.
Click here to listen to an example of an engine misfire.
5. Low MPGs
Although not always noticeable to the naked eye (or ear), poor fuel economy can be a symptom of failing spark plugs. In some cases, old or loose spark plugs may reduce your MPGs by anywhere from 15% to 30%.
In lots of instances, however, a cheap spark plug replacement is all that’s needed to get your car back on track. And if you’re trying to sell your vehicle, this will be a big selling point.
4. Black Exhaust Smoke
Work-out spark plugs can also be the catalyst for thick, black exhaust smoke and higher carbon emissions. When you notice this bad spark plug symptom, it may be time to visit a mechanic or your local auto service center, as it’s more than likely your problem is multi-layered (your catalytic converter could be involved, for instance).
3. Loss of Acceleration
An unresponsive accelerator and a lack of “get up and go” can be the result of dirty or weak spark plugs. Fouled spark plugs don’t catch a spark very efficiently, which can sometimes cause engine sluggishness, especially when gears shift.
2. Engine Won’t Start
When a car engine won’t turn over, there are a few potential culprits, including a bad ignition, broken alternator, dead battery, and defective spark plugs.
If a battery check shows that it’s got enough juice, and there is no corrosion on the terminals or battery cables, the next, most affordable solution is to check your spark plugs (alternators and ignitions are difficult to DIY diagnose). Head to a service center for a tune-up and inspection, and they’ll let you know if you need new spark plugs.
1. Engine “Knocking”
If you don’t address your broken spark plug symptoms in time, you may start hearing engine knocking, which is a very serious issue that will 100% lead to severe engine failure and mechanical damage of important components like piston heads, compression rings, valves, and the engine’s cylinders themselves.
Do not let it get this far! Bring your car into our service center near Kansas City (or any service center) for an inspection and repairs. It could be the difference between you driving home tomorrow and you buying a new car from our Overland Park dealership.
Contact McCarthy Chevrolet of Overland Park at 866-565-8106 to schedule an appointment or request a tow to our Overland Park service center. We’d be happy to provide you with an inspection and get to the bottom of your engine or spark plug problems.
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