Plug Wire Resistance

Do a basic continuity test. They are spiral core wires & its very common for them to break internally. When they do they will still work for a while because the spark will jump the gap but after time they stop.

There are a few good threads around about how to go about rebuilding them. You must use the right (spiral) wire (rather than solid core). Your ignition system will not like you otherwise.

 

I just replaced my wires on a 328. They showed no continuity through an Ohm meter but apparently with the spark plugs i was using there was just enough with the engine running to get keep a current going through them. After replacing the wires, the car runs a good bit more smoothly (and i thought it was running smoothly before!).

 

Good strong spark plug wires should have a resistance of 5000 ohms or less. Over time the resistor wires will increase in resistance.

 

Off the top of my head I believe mine read 9k-13k ohm from cap terminal to plug side of wire extension. This was on new cap, wires and extenders.

 

The spiral wound wires used on a QV typically have between 300 to 700 ohms per foot of wire. t's not critical, but spiral wound wire should be used.

 

What is a reasonable life for wires on a QV?

17 years? Because that is how old mine are now.

 

I replace mine after 25 years because the car was developing a low RPM miss. Several measured "open" so they probably could have been replaced sooner. Best thing to do is to ohm them and if the measure open or infinite resistance, they have breaks in them and should be replaced.