I did the same this weekend. Only I could never get the back passenger side plug out, impossible! Got the other 7, but had to resort to duct taping the socket to the extension so the whole thing would pull back out once the plug was loosenend and free.
Good luck, any thoughts on the back passenger side plug?
ED

 

I'm beginning to realize why there's "Sparkplug Blowout" issues with these motors

 

yeh.. theres a reason ford didnt have a recall on it.. cause all of the problem that occured happend after the uneducated owner changed out spark plugs..instaled them incorrectly. and they blew out.. ive got the 4-5 thread heads.. 145K miles and its been throuh 3 sets of plugs.. and the 4.6 runs higher compression than the 5.4 does! so the plugs are put under much more stress.. and mine arent bowing out.. this whole spark plug blow out issue is not fords problem! its just improper change out

ps u can put a dot of green locktite on the compression ring of the plug if your paranoid that it will come out. but dont put it on the threads!. and dont use red.. tear stuff up when trying to remove.. green isnt as strong but still holds

 

I can see that now lol, starting in on one these motors for the first time, with intentions towards doin a simple plug change. One could easily get sloppy towards the end trying to hurry up - other things to do..I bet that happens quite a bit.
When I change em , I freakin hate chit in my way , so I take off everything off down to the lower intake lol .
No compression rings on my plugs - not sure about others - anti-sieze holds mine down fine. Locktite would work for the worriers, hell, I read in here once that someone used JB weld lol - AWESOME!!

 

theres a washer/ring on top that compresses down to seal.

 

If your talking about that compression washer that's positioned above the SP threads on some, uhmm, NA - these plugs are tappered - never used them for plugs on this truck- didn't come with the motorcrafts I used - plug body then threads, that's it man...Hey did you hit your head or something or are you just makin conversation? lol ( :

https://www.f150online.com/galleries...388&anum=10943

 

i use NGK iridiums.. they use the compression washers like most still do. its a good way to keep from pullin the threads. the tapered fit makes it hard to determine when the plug is snug.. but yes lol making conversation gotta keep the post count up!

 

You have a good point. NGK in my opinion has always been the #1 plug from way back...When it was basically Champion & NGK. I can't think of one application that a Champion plug would out preform the NGK but they survived and I use them in small engines except for the honda motors - Nothing but NGK will do.
I not sure how the Motorcrafts(Autolite's) tapered design could be as effective as NGK's compression washer with the expansion and contraction of metals. I can see the benefit of the compression washer here - I can't see how the tapered fit would be an effective seal. It must somehow - Glad I use anti-sieze - helps a little.
The tapered fit could also strengthen theories of blowout. I haven't heard one bad thing about NGK - speaks for itself..
I purchased my plugs at Carquest which has been my favorite auto parts store forever. I inquired about NGK's, they don't stock them. They insist that the autolites are the best, My truck wouldn't run right on Autolites - they are suppose to be the same as Motorcrafts. Looking and comparing they look identical. I'm puzzled why the Autolites wouldn't work in my motor , I had two cylinders misfire after install and went back to Motorcraft brand.
NGK will be my next plug.

Just makin conversation here lol