Our beloved 02 Focus (I say that sarcastically) has had issue's starting with after it rained it didn't want to start. Lately it's been all the time but once it's warmed up it's fine. It had been getting a misfire code on the 3rd cylinder but I assumed it was ignition related since it had prior coil issues. I tried swapping in a older coil to see if the behavior was the same which it was. Tested the spark plug wires with the multimeter and they tested ok, also tried changing the CPS since it was giving some odd readings but I think the how-to I was reading was incorrect. Finally said the heck with it let's change the plug.. The plug wasn't damaged and looked the same as all the others. But my wife has drove it all week without any issues even after it rained.
I find it odd as I haven't had a bad plug for over twenty years and that was on a Briggs. Disclaimer though I did have to replace the head last year. Possibly something occurred during that time but couldn't say what, it was stored inside and not dropped. She claimed it did the same thing even before the valve seat went out for lunch but can't say 100%. A older plug I saved from the last change is in there now, the new Motorcraft SP504 only had 12k on it. Had two rounds of with a brand new fan clutch being bad but spark plugs...
I find it odd as I haven't had a bad plug for over twenty years and that was on a Briggs. Disclaimer though I did have to replace the head last year. Possibly something occurred during that time but couldn't say what, it was stored inside and not dropped. She claimed it did the same thing even before the valve seat went out for lunch but can't say 100%. A older plug I saved from the last change is in there now, the new Motorcraft SP504 only had 12k on it. Had two rounds of with a brand new fan clutch being bad but spark plugs...