Not sure which catch can you have, mine is designed to work just fine with the cover in place.
I’ve got the Full Race catch can. I actually installed it today… however, ran into an issue as one of the AN fittings on the passenger side would not catch the thread when attempting to attach to catch can. After repeated attempts it ended up stripping out. I’ll go get some pics.
For now I’ll bypass the catch can, and reconnect the PCV connectors until I get this issue resolved. Because I didn’t have time no attempts were made to alter the engine cover to fit. Looking at the pics below will explain why the cover can’t be used unless modded for fit. I specifically mounted the can a little higher on the firewall to allow clearance for the cover. If you look at how this mounts onto the F-150 you will notice it sits almost directly on top of the intake, thus making it impossible to mount the cover. Another thing you might not realize is the F-150’s have the mounting points for Full Race’s two styles of catch cans from the factory. Since our Expedition’s don’t have that luxury I used rivet nuts in the firewall as my mounting points. Just wish I could’ve found black washers to match the bolts. I’ll continue my search. Maybe I’ll just paint them. Below I attached a pic with one installed, and the passenger side painted after drilling, and ready for installation of a rivet nut.
I’ve already got a plan for it once I get back on it. I’ll post completed pics. Not before I cleanup/ coverup those hose clamps with maybe some of those factory style squeeze style clamps. Or, at least smaller ones all the way around. Not a fan of that look. There are more there than I’d like because of the crankcase flow sensor Ford put on the ‘16 Expedition. It needs to remain in the picture during the install for obvious reasons (also states it in Full Race’s instructions; small blurb listed as a “Note”). Funny thing is I’ve never seen that sensor during any of the installs I’ve watched on YouTube. Nor do any of the instructions I’ve read actually show it. Take a look at pic #4, towards the driver side by the oil fill cap, and you’ll see the sensor that monitors flow. For now here are these pics…