Hey everyone, this is my first post, I am new to this site, so sorry in advance if I posted in the wrong area, or had a really long post (I just want to be descriptive). I wish it was to announce something cool I did to my truck, but it is sadly not. I have a 2001 F150 4.6l XLT ext cab, it is my first vehicle, and I love this truck! It has 126k miles. I have had it for over a year now, and I had plans on putting on a new Magnaflow exhaust system on it next weekend, but it rained...and since it never rains in Arizona, I decided to have some fun in the desert. The truck did fine and ran great the whole time, but on my way home my truck started to shake a little and my Check Engine light came on. So I went down to my local O'Riley shop (my truck began to shake more violently as I got closer) and ran a diagnostic when I got there, the error code I received was a PO308 (Cylinder 8 misfire)...crap. Anyway, I have not worked on engines myself that much, but I am wanting to get to learn more, and do some repairs myself. I did some online research on what to do to fix this problem and I have come down to a few ideas.

A) Replace my spark plugs (although I had them replaced about 8k miles ago)
B) Replace Ignition coil on cylinder 8
C) Replace Injector

or something really bad that I cannot do...I hope not

Symptoms:
-Truck shakes in Idol
-Truck shakes alot more between 1000rpms-1700rpms
-No smoke from what I could tell (alot of articles I saw that relate to this problem mentioned smoke from exhaust)
-Doesn't sound good (can hear a small pause between cylinders firing)
-happened after rain....i went through a couple of small puddles (nothing I haven't done before)

I unfortunately live 9 miles away from any Repair/Auto shop, and I want to try and avoid trips with my truck (if i need to go down there, i will use my dad's truck).

Please tell me if my long post was helpful, or annoying. If you have any suggestions on what I should do, please be very descriptive (again, I have not worked on engines very much, and I am wanting to learn!)
I want to try and keep costs down, but if it is worth spending the extra money on a certain part, I will.
If you think it is just worth it to take it to a mechanic, please say so.

Thanks in advance!

 

Remove the #8 coil and blow the water out of the plug well. #8 is the rear plug, driver's side. Reinstall the coil using a bit of dielectric grease in the boot.

 

Ok, thanks glc I will try that... unfortunately, that looks like the hardest one to get to.

 

Yep I just went through that after I degreased my engine only I had misfires on two and 4 so it really shook bad. I had water on the plugs , boots and coils. But yep 4 and 8 are hell to get at. You can try a Q-tip to get water out of the boots worked well for me. Good luck I know the feeling.

 

Ok, I had trouble with a stripped bolt, but I got the coil out now. It looked a little rusted on the inside of the coil, and it was a little wet. I dried out the coil, and sprayed the boot with some white Lithium Grease. I put it back in, started it, and it is perfect! Thanks for the help. Now I will hopefully be putting in my exhaust system soon.