Hello,

I’d like to test my spark plug wires for problems. I’ve inspected the wires and see no physical problems. I don’t have a dark place that I can park the car with no lights to inspect for arcing from the wires.

Can checking the resistance of the spark plug wire indicate their condition? Wires 1 -3 have a resistance of 14k -17k ohms and wires 4 -6 are at 7k – 9k ohms.

Thanks

 

Try it as dark as you can get in practical terms. Then spray down the wires with water from a windex bottle. Your eyesight compensates for darkness to a remarkable degree and the water spray makes the arcing stronger. So it might be dark enough??

OK, here's the long boring story... There's two completely different ways for the wires to fail.

One way is for the resistance to be incorrect. I don't know what the allowable values are offhand, but I bet someone will post before long with that information.

Second way is breakdown of the insulation. That's what you're checking when you look for arcing. There's a company called Megger (megger dot com) that makes test equipment for that. Normal mortals can't afford that stuff so we have to settle for looking for arcing in the dark.

When you set your multi-meter to read OHMS it's really applying a couple volts across the leads & measuring what current results from that. Try that across the insulation of your wires & you'll get zero current (infinite resistance or "open circuit"). A megger sorta does the same thing with thousands of volts applied for a small fraction of a second. Insulation can look good for 20v or 50v but it might break down with 15,000 volts.

 

The maximum for a wire is 25 kohm.

 

Hello,

I was able to take the car into a very dark area to inspect for arching plug wires. I did not see any type blue colored light even when I sprayed with water. Today I was working on the car and notice that on the number 6 cable and the coil (center) cable have a gap between the cable boot at the distributor cap and the cable. Is this normal?

Thanks