I'm having a little argument with my pap, He says I should take the fresh air intake (the Plastic) off from the air cleaner. My question to all of you is, is it worth it to take it off? Thanks! The Engine I have is the 250 i6
He Said that on all of his cars (he Has built cars from ground up for 50+ years) He removes them to get better air flow.
In the summer...no. In the winter...yes. This is why they put a Heated Air Intake System on the air cleaner. When the temp is hot air is drawn through the plastic inlet. When the temp is cold it is drawn through the heated air from the exhaust manifold. http://1bad6t.com/Maverick/repair/emission_controls_02.html
If you are connected to an inlet that gets air from outside the engine bay, leave it hooked up that way all of the pros outweigh the cons. If it is only drawing air from the engine bay, doesn't really matter much.