Testing spark plug wires issue
I'm currently troubleshooting a vibration at idle issue with my 03 focus (turned out to be a collapsed pcv hose but that's a different post).
While testing spark, I used my timing light w/ tach and noticed something strange on the #1 wire. (I adjusted for wasted spark). On #2, #3, and #4 at warm idle, the tach showed ~460rpm. On #1 it showed ~900. Weird. So I ran the test again near the coil and all cylinders show ~460. Except, when I run the pickup down the #1 wire, about halfway it jumps to 700 and at the end jumps to 900.
Am I looking at a defective wire? Or could something else be going on?