I replaced the plugs successfully (no breakage) on my '04 5.4.
I had 48,000 miles on the truck.
The plugs were ALL carboned up, every one. Carbon up near the seat, and carbon in the middle of that lower shield.
The carbon was NOT extremely hard, it could be rubbed off (most of it anyway) with effort. If I knew how to take the pictures, I would show you all. If you take the 2 worst of Quintin's plugs, mine were all like that only add some caking up near the seat.
My opinion, for what it's worth, is to do it BEFORE 50,000 miles.

But I have a question. I bought everything and installed it before reading all your notes about plug numbers (assuming the Dealorship knew best).

I found PZT 2 FE plugs in the truck. (Not the PZT 2FE-F4's you are writing about)
They gave me PZT 2 F plugs (Not PZT 2F-F4's you are writing about)

Does the F4 part of the number refer to a 4x4 truck?
I have a plain ole 2 wheel drive.

And would that TSB saying replace the 2F's with 1F apply to my truck?
The build date is 6/2003.

I have not experienced any knocking or detonation (before this change over anyway!

Thanks for any help.
If I have to replace those plugs, at least it will be easy to do now!
KN

 

Wow. Nobody has any plug information? I guess they're scared to do it.

I don't have the info you need, the dealer did my plugs on the tsb and put the right ones in, according to them.

 

PZT-2 plugs are one heat range hotter than the suggested service plug, the PZT-1. In some '04 and '05 engines, Ford suggested replacing the factory PZT-2s with 1s because of knock/detonation problems. IMO, it doesn't matter on an average ordinary bolt on truck - I run PZT-2s in my truck with 87 octane unleaded bone stock with no problems. On a truck with tune/intake/exhaust and especially a supercharged truck, I think a colder range plug would matter a lot more, but for a stock or mostly stock truck, either one is fine.

 

Okay, I feel better about the 2's in there instead of the "recommended" 1's,
but what do all those letters after the plug mean?
Why did my old plugs say PZT2 FE and the new one has no "E"?
And neither the old nor the new had the "-F4" you have written in your plug numbers, like "PZT1F-F4"
What is that about?
Of Course, The dealership said they are the "right" plugs, but ??? how can we know. The one man just about had a fit when I turned his computer screen around to look at it myself.
Ha.
KN

 

There's a breakdown of what all the numbers and letters in a spark plug's part number mean, I'll try to find it tomorrow at work.

Also, for whatever it's worth, Ford changes part numbers on plugs several times a year. I mean, they can be the exact same plug, same heat range, thread, everything, but give it a few months, and it'll have a different part number.

 

Well that might explain the "FE" denotation on my original plugs.
Maybe in '03, they had a different number.
Maybe the "F4" is the newer version.
I was wondering if it meant some sort of change in design.
In the 2 days of 'new plugs' driving, I have noticed NO difference.
No pings, no stutters, no detonation. Just quiet motoring.
Thank you Quintin.
KN