I am have installed a 2008 5.4L into my 2007 Expedition. The new Coil on plug boots are brown and the plugs themselves are different. Will the old style coil on plugs work if I change the boots to the correct color? Also is there a notice I need to place on the vehicle that it has a replacement engine?

 

what did you end up finding out. I am at this point now

 

Sorry to resurrect an old thread, but the information my help others later. I ran into this similar issue when I replaced my 5.4L 3V (black boot) in my 2007 F150. The engine matched up perfectly with wiring harness and connections in the F150's engine bay. I purchased a nearly complete rebuild from NAPA that included oil pan and valve covers.

After installing, it was started for the first time. The engine started with a bad ignition miss. Could not figure it out immediately so just shut it off. Next day, found out that I had the newer style plugs in the block, i.e. new brown boot heads. I researched part numbers on the COP and just decided to throw caution to the wind by purchasing the 2010 coil boots for the 2010 5.4L 3V. After replacing the each black boot with the half inch longer brown boots, the engine started and idled perfectly smooth. So honestly, unless someone shows a COP spec sheet with the exact difference between a black boot COP and brown boot COP, I believe it is only 1/2 inch of silicone. The brown boots are 1/2" longer than the black boots.

 

That 1/2" is a significant difference. Imagine the misfires if you left spark plug wire loose by a 1/2".

 

It misfires significantly but the wire inside is the relatively the same length, years of being installed on the previous engine causing some shrinkage. The 1/2", as it seems to me, is there to get the boot over the new style plug. The new style plug is no longer the long reach style, but looks more like the old standard plugs. As a consequence, the black boots barely touch the plugs. Maybe I am wrong and the COP is different as well, idk.

I just changed to the the black boots to the brown boots, and replaced the wire inside. The engine has operated happily the last 15 months with 20,000 miles since the replacement engine was installed.