Ignition problems have a way of starting small. The car still drives, but it feels slightly off in a way you cannot fully describe. Then one day the issue becomes obvious, and you’re stuck wondering how long it’s been building.
Spark plugs and ignition coils are common wear items. When they start to fail, they can cause misfires, rough running, and fuel economy issues. The good news is that the warning signs are usually pretty clear once you know what to look for.
What Spark Plugs And Coils Actually Do
Spark plugs ignite the air-fuel mixture in each cylinder. Ignition coils provide the high-voltage spark that ignites the combustion. In many modern engines, each cylinder has its own coil mounted right on top of the plug.
As plugs wear, the gap grows, and the spark becomes less consistent. Coils can weaken with heat and age. Either issue can cause incomplete combustion, which is why the symptoms often feel like hesitation, roughness, or lack of power.
1. Rough Idle That Comes And Goes
One of the earliest signs is an idle that feels uneven. The car may shake slightly at a stoplight, or the engine may feel like it is stumbling once in a while. It can be subtle at first, especially if it only happens when the engine is cold or when the AC is on.
A single weak plug or coil can cause a light misfire that you barely notice, then it gets worse as the component degrades. If the idle gets rougher over time or if it comes back repeatedly, it is worth having the ignition system checked.
2. Hesitation When You Press The Gas
When plugs or coils are weak, the engine can hesitate under load. You press the gas to merge or climb a hill, and the response feels delayed or uneven. Sometimes it feels like a brief stumble, then the car catches up.
This symptom often shows up during acceleration because cylinder pressure increases under load. A weak spark struggles more under those conditions. If the hesitation is consistent or if it is getting more frequent, ignition should be on the suspect list.
3. A Flashing Check Engine Light During A Misfire
A flashing check engine light is not something to ignore. It often means the engine is misfiring severely enough that it could damage the catalytic converter. Even if the flashing stops and the car feels better, the event matters.
Misfires can be caused by plugs, coils, fuel delivery issues, or air leaks. Still, plugs and coils are common culprits, especially if the vehicle is due for service or if the misfire happens under load. If the light is flashing, it is safer to ease off the throttle and schedule service as soon as possible.
4. Drop In Fuel Economy Without A Clear Reason
When combustion is inconsistent, the engine can burn fuel less efficiently. That can show up as a noticeable drop in miles per gallon, even when your driving habits have not changed. The car may feel like it needs more throttle to do the same work.
Fuel economy drops can also come from tire pressure, sensor issues, or mechanical drag. Still, if the drop pairs with rough idle or hesitation, ignition wear becomes more likely.
5. Hard Starts Or A Longer Crank Than Usual
Spark plugs that are worn or fouled can make starting harder. Coils that are weak can also struggle during start-up when the voltage demand is high. You may notice the engine cranks longer before it fires, especially after the car sits overnight.
If hard starting is paired with a rough idle right after it starts, that combination often points toward ignition issues. It is also a reminder that ignition problems do not always feel dramatic at speed. Sometimes the biggest clue is what happens in the first few seconds after startup.
Common Reasons Plugs And Coils Wear Faster
Normal age is the main reason, but certain conditions accelerate wear. Short trips can increase carbon buildup because the engine spends more time warming up. Oil leaks into plug wells can damage coils over time. Running overly lean or overly rich can also stress plugs.
If you have had a valve cover leak, for example, oil can seep into the coil area and create misfire problems that look like a bad coil when the root cause is the leak. That is why inspection matters before simply swapping parts.
When To Schedule Service Before It Gets Worse
If you are seeing a flashing check engine light, strong hesitation, or repeated misfires, schedule service quickly. If it is a mild rough idle or occasional stumble, it is still worth checking before it turns into a no-start day or catalyst damage.
A good diagnostic will confirm whether the issue is plugs, coils, or something else, like a fuel or air problem. Replacing parts without confirming the cause can get expensive fast.
Get Spark Plug And Ignition Coil Service in Plano, TX, with Davenport Motor Company
We can inspect your ignition system, identify which cylinders are misfiring, and confirm whether spark plugs, ignition coils, or related issues are causing the problem. We’ll recommend the right service interval for your vehicle and make sure the repair solves the symptom, not just masks it.
Call Davenport Motor Company in Plano, TX, to schedule ignition service and get dependable performance back.