My wife's 2005 Expedition with the 5.4L 3v engine seems to have blown #4 spark plug.

She was driving home the other day and hear a bang then what sounded like a serious exhaust leak. Reading the codes, we had a misfire on #4 and #5 spark plugs. So we change the coil on #5 (easiest to get to), and start working on #4. The coil comes off, but the boot is split in two lengthwise and in general looks in pretty bad shape. I forgot to take a picture of it, unfortunately.

Anyway, I take out what is left of the "plug".


Next to a new plug.


So I look down the plug well with an inspection mirror, and later take a few pictures with my digital camera. I can't tell if there is anything left in the hole, or if the threads got stripped out when the plug blew.







I guess what I'm asking is if anybody knows or can tell from these pictures if the electrode is "stuck" in the head or if the threads are even intact. Any help or advice would be appreciated.

Thanks,

Brian

 

from wikipedia so may not be totally accurate but the TSB is listed

Spark plug issues

2-valve 4.6 L, 5.4 L, and 6.8 L engines found in many 1997–2008 Ford, Lincoln, and Mercury vehicles have an issue with stripped or missing spark plug threads in the cylinder heads. Ford acknowledges this issue in TSB 07-21-2 as well as earlier TSB's. Ford's TSB does not state that this issue is caused by owner neglect. Ford's only authorized repair procedure for out-of-warranty vehicles is to use the LOCK-N-STITCH aluminum insert and tool kit. For vehicles under the New Vehicle Limited Warranty, Ford will only cover the replacement of the entire cylinder head; however, the Ford recommended spark plug service interval extends beyond the duration of the New Vehicle Limited Warranty.[50]

3-valve 5.4 L and 6.8 L engines built before 10/9/07 and 3-valve 4.6 Ls built before 11/30/07 found in many 2004–2008 Ford, Lincoln, and Mercury vehicles have an issue with difficult to remove spark plugs which can cause part of the spark plug to become seized in the cylinder head. The source of the problem is a unique plug design that is made with a 2-piece shell, which often separates, leaving the lower portion of the spark plug stuck deep in the engine. Ford acknowledges this issue in TSB 08-7-6 as well as earlier TSB's. Ford's TSB does not state that this issue is caused by owner neglect. The TSB provides a special procedure for spark plug removal on these engines. For situations where the spark plug has broken in the head, Ford distributes multiple special tools for removing the seized portion of the plug. The multiple procedures required for the different cases/situations of plugs seized in these engines are explained in the TSB. This repair is covered for vehicles under warranty; however, the Ford recommended spark plug service interval extends beyond the duration of the New Vehicle Limited Warranty.[51]

Federal-Mogul, parent company of Champion Spark Plug, and Brisk Silver Racing have introduced a 1-piece machined shell 3-valve spark plugs that addresses the OEM 2-piece spark plug's separation issues.[52][53]