I have a 2000 5.4 F-150 with 140,000 miles. Recently during a rainstorm I noticed my truck started to misfire and shake a lot. It rained the entire night so I waited until morning to check it out. I discovered that the hose that carries washer fluid to the wipers had fallen off and was leaking water over my coils. So in fact it wasn't rain water affecting my cylinder but it was windshield wiper fluid leaking into it, and since I only use wipers during the rain I initially thought it was rain.

Anyways, after the check engine light turned on, I hooked up the computer and it came up as misfiring on cylinder 3. I purchased a coil and boot on the spot and changed out number 3 but it still hasnt fixed the problem completely. The misfires are fewer than they were yesterday but it still has random misfires and still shakes.

I was getting very frustrated at the idea of having to possibly change out the sparkplugs, (not mechanically a wiz but I try) However, my mom told me in her expedition, (4.6) she had the exact same experience with the wiper fluid leaking over her coils! She told me after she changed the bad coil the truck still shook and took over a week to fully dry out and go back to normal which it did on its own. Someone else told me something along similar lines. This just seems hard to believe for me. Is it true? Is my work here possibly done? (fwi my check engine light cleared after I changed the coil and has remained off since I kept driving it) Thank you in advance.

 

It doesn't take much moisture to create a short especially around a coil. Washer fluid has other chemicals in it that take longer to dry than just water, so yea it could take a week. You can try spraying WD-40 on it. It will help disperse the moisture and speed up the drying process. This is actually what it was originally designed to do. Good luck

 

Thanks I appreciate it. So where should I spray it?

 

Sorry I was off line. Spray all around the coil you just replaced especially on the power connector. Spraying along the entire bank of coils on that side of the motor to insure all of the water is dispersed. Good luck

 

Did you replace the plug as well ? It may have fouled out meaning by changing the COP, you fixed 50% of the problem and the other 50% might be the plug. Good luck

 

Hey guys, I took it to my uncles shop. Its a hike away but it was worth it. All new plugs and all new coils (he said coils were all original) and now the truck runs fantastic.

 

@ 140K miles ...I was going to suggest a tune up...good to hear it's fixed.