Anyone have any ideas? Rain...Misfire....
 

Been having a problem for a few months. Thought I had it licked then it happened again last night.

I have been having a problem with misfires. My truck is a 2002 F-150 5.4 V8 with 130k miles. When ever this has happened in the past I would pull the code to see which cylinder then take the COP off and the plug out clean it and re-install. This normally fixes the problem. Well last week I had 2 plugs misfiring, so I decided to do a full tune up. After, the truck ran great. I mean really great. Interesting note, the 2 plugs that were misfiring has fluid in the spark plug well. I did the following:

Sea foam engine treatment
Injector cleaning treatment
Oil and oil filter change
Fuel filter
Air filter (K&N)
New plugs with thread anti sieze and a dap of dielectric greese
PVC valve

Well last night on my way home it started to rain. And as soon as it did, it started misfiring again..........And now that I think of it, last year when this happened it started during a rain storm.

Does this happen to anyone else?

Anyone have any ideas?

How much rain, and is water getting into the plug hole between the COP and plug? I had this happen muddin, and fried some plugs. Sometimes the boot on the COP wears our/rips/etc. and water gets in there. Also are there any holes/tears anywhere along the intake line from the filter, to the manifold?

Definately need to check the boots for tears that desq27 mentioned. If you are saying that you are getting misfire codes, and if the codes are for the front, easier access cyl's., you may be able to run it in a garage with the lights out or outside when dark and may be able to see some arcing. Don't be afraid to use more than a " dap " of dielectric grease. Hope this helps

130,000 miles - Time for a COP changeout, the best thing for your ignition probs - theres more going on there than your aware of. The #1 tuneup for these modular motors. COP motors are a high tech design and keeping your ignitions integrity is important to your engines performance.

To cut to the chase - Kevins store "Global Automotive" sells eight COP's for these motors for $96 (that's for all eight!!) .. Many people on this site purchases COP's from Kevin..

Change them all at the same time to make a very noticable difference in the way she runs.. -

http://cgi.ebay.com/ebaymotors/NEW-I...mZ160098818320

https://www.f150online.com/galleries...940-186164.jpg

When you swap them out , use plenty of dielectric grease and follow Matts instructions if you need help -

https://www.f150online.com/forums/li...parkplugs.html

https://www.f150online.com/galleries...940-185977.jpg https://www.f150online.com/galleries...939-182931.jpg

Matt's instructions do not mention dielectric grease. How much is enough?
I have already switched out 3 COPs on this motor in the last year.

Yup and you still have weak ones , the motors under duress. What happens is that you'll keep replacing one at a time rather quickly for rest of the trucks life and during this time / never having the truck run to it's full potential.

Replacing all at once wakes the motor back up and equalizes your ignition pulses.

I know these ignitions and threw trial and error , I have determined these findings in the field..

Use your own due-diligence it's your ride, I'm just sharing what I have learned.. :thumbsup:


If you need an explanation on the grease procedure , just ask - I'm not sure if your asking at this point..

here's a link to a thread I started, it has some of the same pics as in this thread but explains a lot better. hope it helps :beers:

https://www.f150online.com/forums/sh...d.php?t=278351

Thanx BSL , I don't have to explain the grease part again :lol:

That's cool :beers:

You can replace all the COPs and plugs with fresh ones and still run into the problem the next time you have a good rain. I replaced all my plugs and COPs a couple months ago but I figured water is getting to my plugs/COPs somehow.

I shut the hood and shot water at my windshield to simulate rain. Popped the hood and sure enough I could see exactly how water was finding itself past the bad weather seals and onto the COPs (only 86K miles on my truck). I used some silicone sealant on where water was leaking, then everywhere else for good measure and now it's water tight under the hood.