My '07 had the check engine come in the other day, engine misfire. I took it to the dealer hoping it was a coil, which thanks to the 100,000 mi warranty from Ford I was hoping would be covered. Sadly, and of course, all coils tested fine, turns out 2 plugs were bad. They replaced all 8 plugs, plus a plug boot, to the tune of $600. Thankfully, not one plug broke (truck had 80k on it) so no extra cost there. So much more, but peace of mind that all the plugs are new one piece plugs is great. He recommended that they should be replaced every 60k to avoid any issues. Anybody heard this?
The plugs are still 2 piece but are stronger than the original design. Ford changed the heads in late 2008 and those are the only ones with a 1 piece plug. You can identify a 1 piece plug engine by brown coil boots.
I have my truck at a mechanics house now,well trusted guy IMO,he called me tonight said 3 plugs broke off,has to order a special tool now to get them out being a holiday weekend it will be wed. next week before it MIGHT be done,truck has 86K miles on it,and at $13.00 each plug REDICULOUS.......
I changed mine last winter, broke all 8. Replaced with Champion one piece. Truck runs perfectly as before with no difference. Won't have to deal with those piece of **** Motocraft plugs ever again. Why they never changed their design is a mystery, maybe job security for their dealers.