Ok, I'm bad, go ahead and flame me, I deserve it. 5.4 in the truck has 139K on it and still on the original plugs as far as I know, I got the truck with 32K on it. 2 days ago in 95 deg. heat and 90% humidity I was running the AC on max on the freeway for about 40 minutes bringing my mother in law over to our house, engine was running fine. Truck sat for about 45 minutes in the driveway and when we went to go out again, the engine was missing...badly as in one totally dead cylinder. The CEL started flashing for a minute or so then stayed on. Still bad on the way home 3 hours later. It was somewhat better the next day but still missed.

Spent all last last night on here reading up on plug changes and bad COPS. Went to AutoZone today and they read one single code "Misfire Detected on Cylinder 5", which I'm told is the drivers side front cylinder.

But a funny thing happened on the way to AZ...it started and ran just fine, the miss is totally gone, great power again.

So my plan is as follows:

A. Run a can of Seafoam in with the fuel. After I burn that,
B. Clean out the plug holes with shop vac and PB Blaster
C. Change the plugs with the OE Motorcraft SP 479's using no anti-seize and the engine dead cold. Torque to 13 ft-lb where torque wrench is usable and snug + 1/4 turn (give or take) elsewhere.
D. Order a set of COPS from eBay and put them in at the same time, using dielectric grease.

I've got lots of 1/4 & 3/8 standard and wobbly extensions and both standard 5/8 spark plug and universal 5/8 spark plug sockets, as well as a plain deep well 5/8" socket, plus the 7 & 8mm 1/4 drives. Also the 3/8" hose for plug installation.

Questions I have...
1. Did I capture the essence of the general consensus on here?
2. Am I going to be OK after I do this?
3. Any other suggestions or comments (other than the flames)?
4. Broken plugs aren't an issue with Y2K 2V engines, just the '04+ 3V's, right?
5. Does anyone think this had anything to to with either the weather or the AC on max?
6. The way it cleared up seems an awful lot like a moisture shorting issue, but isn't #5 well away from where condensation from the AC might affect it?
7. Or was the heat, humidity, extra engine load from the AC, and freeway running just enough to stress an old ignition system to the point where it says fix me before I quit on you all together?

Thanks to all on this forum, this place is awesome! Oh yeah, and I should plan on beer at the rate of about one per cylinder, right??? Damn, I knew I forgot something at the store!

 

I don't know about the seafoam but changing the plugs can't hurt. I used compressed air to clean out the plug holes before taking out the plugs. I had oil in a couple of mine. After the first few it gets faster until you hit the ones at the back of the firewall.

Another tip I thought was good was letting some air out of the front tires to help get over the engine. Use a rubber tube that fits over the end of the spark plug to help get the new one started without cross threading.

Good luck.

 

Good Job! , you'll be fine..

Time will tell

The full plug changeout , I remove the front tires and drop down on blocks if it's a 4x4. Once a tire has been flattened - the steel belts are never the same..

When greasing up the boots , be liberal with the stuff and don't worry about getting grease on the spring when reinstalling the boots.

After COP install - grease the void between the boot and cylinder head to keep water and debri out of the chamber. #10 O-RINGS work better for this if you desire the extra preventative step.

Correct.

Nah, not in this case. Just an age thing..It's been a good runner for a long time

You had a blinker (Malfunction Indicator Lamp (MIL) and the a solid light as a follow up. When scanned , you reported a reading of PO305. If there was no leane codes present , that solid MIL would indicate primary failure on 5.
Plug failure is my guess seeing how it resesitated itself. Usually 5 doesn't have moisture problems.

Sounds like you and your truck have a good relationship..



X2 for #4 and 8 ...

 

All's well with my truck again after my plug & COP install. I've got about 5K on them now and she purrrrrs like a kitten. Since then I've also cleaned my IAC and MAF and replaced a faulty thermostat. Kinda like fallin' in love all over again.

Two suggestions for others...(1) leave the fuel rail alone and get a 7mm socket with an integral universal to get at COP #7. I think it was like $7 at Sears...cheap peace of mind to keep from needing to pull the fuel rails. And (2) Harbor Freight had an extended (like 5" long) 5/8" spark plug socket I got. With it you can use the plug socket to install the plugs and not worry about getting your plug socket stuck in a hole somewhere, it sticks out the plug hole about a half inch. It was just under the diameter of the plug holes so if the plug goes into the socket even halfway square, you can't cross thread the plugs on installation.

Actually the job was a lot easier than I thought it would be after reading some of the posts on here.

Oh, and I was able to use the torque wrench without a universal joint for 7 of the 8 holes without fuss. I think #4 was the only one where I didn't get the torque wrench in w/o a universal, and even then the angle wasn't very big, so I just gave her a little extra tug after the wrench clicked.

You guys are awesome!

 

change the coil on that plug to that should take care of it