You start your car on a damp morning. The engine sounds like it’s struggling, and for the first moment or two, it acts like it’s low on power before returning to normal. Or, maybe you have a newer car and you’ve just gotten a diagnostic trouble code indicating a misfire. What happened here? In both cases, your ignition wires are a suspect for this kind of behavior.

What exactly is going on, though? Well, with older ignition wires, the constant heating and cooling with the engine ages the outer rubber insulating layer on the wires. Once this layer dries out and cracks, stray sparks will find the shortest path to close the circuit. Rather than making it all the way to the spark plugs, this often means the spark will ground itself out against the head or engine block, causing a momentary misfire, and the aforementioned stumbling condition. At any rate, the only cure in this situation is new ignition wires.

Quality of ignition wires can vary, as can different ignition systems’ reaction to aftermarket parts. Do your research here. However, most quality aftermarket ignition wiring will probably be a pretty safe bet. Once you’ve selected your new wires, it’s time to replace them.

Replacing ignition wires is a great job for the beginner do-it-yourselfer. There’s just a few simple things to keep in mind to make sure the job goes smoothly. First off, replace ignition wires with the car OFF. For added safety, you can disconnect the battery’s negative terminal, though this isn’t usually necessary. After that, don’t just tear into things. Look things over. If it isn’t painfully obvious, draw yourself a quick diagram showing ignition wire placement. These wires are routed in a particular order and mixing them up is a guaranteed recipe for a misfire.

Next, replace the ignition wires one by one. Don’t disconnect them all at once. Again, this is to avoid misrouting ignition wires. That’s pretty much all there is to it, but there are some other parts you should inspect and perhaps consider replacing at this time.

Chances are if your ignition wires are that badly aged, other parts may be in need of replacing, too. For older cars, this is a good time to inspect and possibly replace your distributor cap and rotor. For all cars, regardless of age, you should take a look at and replace your spark plugs if they’re at or past the manufacturer’s recommended replacement interval.

Remember that ignition wires, even though they appear stationary, are a wear and tear item like many other parts of your engine and do require periodic replacement. Thankfully, it’s an easy job and one that will make an immediate difference in your car’s behavior.