I have a 2003 EB with the 5.4 and 4WD. After a stay at the dealership which included replacement of the #1 cylinder plug, coil, and injector, they found that the intermittant firing issue on the cylinder (which has good matching compression with all others) seems to be related to something upstream, namely the PCM power control module. They feel something is flaked out in the PCM and it will (and has after new parts) continue to be an issue. So next step is a replacement PCM - at thei quote of $800+ installed.
My question - I can acquire a refurb PCM on the aftermarket for a lot less, but other than the physical swap (which is quite simple considering it's location on the firewall) what else is required? I've not gotten a straight answer as to whether a re-flash or reprogramming is required, typically dealer-only due to required tool. Is the PCM plug and play? Or not (as in, after I plug it in the truck won't start due to vehicle theft security or some other issue)?
Some help or direction is greatly appreciated. This thing is nothing like my old Nissan race car...

 

There's nothing wrong with your PCM. If there were a problem with the PCM it would affect more than just one cylinder. They misdiagnosed which cylinder is misfiring, or the problem is with the wiring from the PCM to either the COP or the injector.

But if you insist...I'm fairly certain you can buy a used one and just swap it out with your's. The important thing is to make sure the numbers match between the two PCMs. You can usually find used Expedition PCMs on eBay for just under $200.

 

Swap the PCMs on your own and you'll have to tow the truck back to the Ford dealer to get the PCM reflashed (PATS)...

 

Better yet, swap it in their parking lot then walk inside and ask for the reflash.

 

If you check around I think you will find some parts stores will do a reflash for 50 to 75 dollars no mater where you buy PCM. At least around me they do.

 

Not necessarily true... the injectors are ground side driven by the PCM, if one driver is fried in the module it will affect only one cylinder as they are individually driven.

You should have power at each injector with key on engine off, test with a test light, the other terminal should glow very dimly if you test for ground with the light, when you fire it up (engine running) the ground side terminal will flash the test light very quickly, if it remains dim you have a driver problem in the PCM.