My truck is a 03 Supercrew FX4 w/ a 4.6, and it appears to missfire after I go mudding with my friends.

Now bear in mind that my friends and I do more splashing around than serious "4WD only" type mudding.

I seems to pickup some mud/water down in the spark plug hole and it causes my truck to misfire. Most likely, blocking coil pack from properly sparking the spark plug.

It seems the COP rubber boot does a terrible job from stopping foreign matter from getting down there.

Granted, I did have the whole Spark Plug stripping threads issues a while back ago, but have sense had a professional heli-coil the plug in there. Reason I tell this, I still have not replaced the Coil Pack and it does not attach to the one bolt mounting spot and there for bounces around as far as the fuel rail allows it to. (I hope that made sense to ya'll, if you have had the spark plug thread issue it should have)

So my question is this; Is there any way, either aftermarket or 'custom', to prevent dirt, mud, and/or water from getting between the spark plug and coil pack and causing these damn missfires?

Thanks F150 Online in advance,
Chris

 

Good Question.

 

Yeah I got a FX4 Off Road, that doesn't like to off road. False advertising!

 

So I removed the COP and anything else that was in my way of seeing the sparkplug hole clearly (i.e. intake, power steering fluid reservoir, etc.) and found wet mud on the bottom of the COP (no surprise) then I tried to clean out the plug hole as best I could with a rag and my over sized hands. Then I pulled the spark plug (carefully as to not upset the easily angered plug threads) when I got the plug out it was covered in mud (again no surprise) I cleaned the COP and Plug to get all the wet mud off. But I knew the spark plug would just get dirty agian since the hole probaley had a bunch of mud in it. I needed something to absorb the mud and had a a way to control it in the spark plug hole. Then I got an idea (your gonna love this)! I went inside and stole on of my wife's tampons!?! LOL I knew it would suck up all the liquid mud still in the saprk plug hole and had a string on it that I could easily pull out.
So I put the cotton missle in the spark plug hole and used a socket extension to push it down and pulled the string to raise it up, I repeated this process a few times and then would rinse the "rag" out, and do it all over again, until it came out clean. Then I reasembled everything and fired the truck up. no more miss!
I can't believe the ideas I get!?!?

But this still leaves my original question, How to I stop mud/dirt from getting down there in the first place??

 

The boot should seal the hole. But it can only seal the hole if the COP is bolted in place. Find a way to secure it in its proper place.

 

True it should. But even back when I had it completly bolt down, it would start fouling everytime I tried to clean/wash the engine bay after mudding

 

i got a 4x2 2001 F150 XLT with the 5.4L. I've been in the mud a few times. But the next morning, my truck will idle at about 1500 rpm, it's usually at about 700-1000. I'll put it in to gear and it will take off quickly compared to usual. Anybody else have this problem?

 

What does a high idle have to do with a miss? Please don't hijack threads.

 

What was used to repair the stripped plug? Was it a Helicoil or a Timesert? If the Helicoil is coming loose it may be the cause of the miss. If the coil is not sitting properly on the plug it may be causing the miss. Was the boot and or coil replaced when the plug launched? It may have been cracked or the boot damaged and it only acts up when wet. It may have been that way all along even before the plug launch. Swap coils and see if the miss moves.