Spark plug wire impedance...?

kergilman · 06-22-2008, 02:14 PM

So I am checking out my plugs and wires yesterday and looking @ my Haynes manual, it states that all 4 plug wires should ohm out to about 8k for impedance.
The plug wires I have for cylinders 1, 2, & 3 ohm out at about .5k and cylinder 4 @ 3.5k. I used another DMM and returned the exact same results. Do I need new plug wires already or am I missing something here...?

Anyone else have a reference...?

Defiant · 06-23-2008, 03:38 AM

If you aren't running poorly, I'd not worry about the wires' impedance. I've not meter-checked a wire for over twenty years. It's too cheap to just get a new set.

gsx951 · 06-23-2008, 04:36 AM

What you are measuring with your meter is DC resistance, which is different from impedance.

Either way, as long as there is continuity in the lead and there are no breaks in the insulating jacket, you are good. The output from your coil travels as an electro-magnetic pulse over the surface of the conductor, so the value of the measured resistance (or impedance) really doesn't effect the ability to spark.

Spark plug wires have fairly high resistance to suppress the emission of radio frequency noise. Some people believe that lower resistance wires are better because they will conduct more power to the plugs but since the transmission is skin-effect, there is no truth to that.