Spark Plug Wire Resistance Values

[sethmorgan]

I'm tracking down a slight idle issue with my 2002 XLT 4.0L SOHC, and I'm in the process of narrowing down possible culprits. I was hesitant to check the wires since I replaced them less than 4,000 miles ago, but a resistance check yielded the following values (they are arranged from the point of view of standing in front of the truck):

[3] -- 17.09 KOhms [6] -- 10.87 KOhms
[2] -- 10.97 KOhms [5] -- 09.82 KOhms
[1] -- 08.05 KOhms [4] -- 04.80 KOhms

Coil Pack
[1][2][3]
[5][6][4]

Front of Vehicle

The wire going to cylinder 3 is the longest, and at 34" is about 6K Ohms/ft. These are Motorcraft Wire Set part #WR6096. I did find this post: http://www.explorerforum.com/forums/showthread.php?s=&threadid=95383, and my values are higher; one poster states over 7,000 Ohms is unacceptable. I've seen other data that states between 10,000 and 15,000 Ohms/ft is normal. So do y'all think these are acceptable? I couldn't find published acceptable ranges for this wireset.

 

[MrWizard]

Resistance Values

Resistance probably doesn't have anything to do with your idle problem.
The resistance values are all similar. It would be unlikely that all the wires are bad.
And if they were, you'd be getting an occasional misfire, which would likely cause a
Check Engine light condition. And if they are fairly new, it is unlikely they are cracked and arcing.

That said, I just happen to have measured the values of my plug wires a couple of years ago.
On the OEM wires, one bank were all around 3-4K Ohms, the other bank, with longer runs,
were in the 5-6K Ohm range. I'd guess there is nothing wrong with your plug wires.