Moonshine

Lol syn...one would assume that you wouldn't spray directly into the air filter!

If you have to spray engine...spray it with it running. I wouldn't recommend spraying the engine though. Just get a few cans of engine brite and a bag of Terry towels and go to town!

ModMe

clothes steamers work good for engine cleaning. Keep away from the spark plug boots and any sensors and you really shouldn't have any problems.

Sxynerd

What a paradox it would be if the OP really had a 5.4 and not a 4.6.

Ron505

I just cleaned my engine bay yesterday. On a cold motor, I wet it down with the finest mist setting on the power washer at about 3-4 feet away, just wet it. then spray a degreaser (purple power) on everything. Let it set for about 2-3 minutes, and spray again far away from the motor, and just enough to get the detergent off. Then coat most of it with WD40, especially the coils, wires and electronics. Then use a air hose to blow out any remaining water/WD40. Wipe, and she looks like new.

I've used this method with about the last 6-8 cars that I've had, never had an issue.