Misfire: Spark Plug Wires

[phils97bonn]

97 Bonn SE, 120K mi.
Symptom: Occasional misfire when cold.

So I've looked at a bunch of things to try to fix this: MAF sensor, IAC valve, temp sensors (IAT and ECT), and last but not
least the spark plug wires. I got to thinking about it, and I've never replaced them on this beast. I've owned this car for 12 years (I know, my bad). So yes, the plug wires should've been one of the first things to check. I did the 'ol resistance check on 'em last night and lo and behold! 2 of the 3 wires I checked were completely open circuit (infinite ohms). I couldn't believe the car could run as good as it does this way, so I measured them again about 3 more times - same reading. COOL! I thought to myself - this is the problem!

So I go down to Napa and purchase a set of Belden Premium wires and just for the heck of it, I measured the resistance on the new ones.
4 of these wires measured around 350 ohms, 1 @ 26,000 ohms, and 1 around 1000 ohms. Holy Crap! Not even close to the specs on 5 wires! (specs say around 5K - 25K depending on length of wire). I returned these and ordered some AC Delco online. What a quality control problem Napa has!

I don't know what problems if any this would cause, but I ain't puttin' these on my vehicle. I have definitely lost faith in most 3rd party auto parts after this.

Moral of the story: Check the ohms on your old or NEW plug wires!

[justdave]

From your results, i would suggest double-checking your V.A.R. Instrument (yeah, i know, everbody calls 'em a VOM, but the gadget doesn't "meter" anything), using known values of high-tolerance resistors. Get several, to check ALL the ranges of your instrument. i.e. - 5ohms, 1K ohms, 10k ohms, 1 Meg ohm. And of course, clean the surfaces you are connecting-to with some emery cloth or similar first. And be aware that if you are holding the probes of your instrument onto the wires or crimp-on connectors of the items you are checking...with your fingers...that your body DOES also conduct electrical current (everbody's through-body resistance differs), and can throw off your measurements

[phils97bonn]

Yes, I was very careful how I measured the wires using my DVOM pro quality Fluke meter (former Computer/Electronic Tech.). As for the results on the Belden wire set I couldn't believe it, that's why I measured them 3 times and got the same result 3 times. I have no idea if this is a common problem pervasive throughout Belden's wires or if its just a rare anomaly that I got a bad set. I somehow doubt it was just an isolated incident however.

Received the new AC Delco wires today and they spec'd out perfectly:

from 5k ohms on the shortest to 13.5K ohms on the longest wire - right in the middle of the range of the specs for this car.

My advice: got Belden? Check 'em!