I've been reading about various air intake systems on the web. I have an '04 F150 5.4l (new style). Rather than investing in an intake system, why not just remove the breather tube that connects the air box to the fender well where the intake hole is? Sure, you will have clean your air filter more often but that's cheap and it may not be as efficient as the aftermarket items but doing this is free (except for buying the truck of course!). I experimented with this and experienced significant increases in engine response and power as more air was allowed into the engine. Don't know about mileage yet. Have other members here done this? Any inputs-thoughts?

 

It is not somthing I would do because the ACT sensor will sense the hotter air from the engine bay and react by changing the computer running conditions in the wrong direction (less power). This is why the factory put cool air inlet systems on the truck.
For every 10 degrees increase in inlet temp you lose close to 1 hp.
The difference between the outside temp and the engine bay could be as much as 50 degrees depending on the outside temp. This example would mean about 5 hp loss at least, just based on temp difference then add what the computer does with it.
Doing what you did could possibly improve fuel milage but you can't have both better fuel milage and more power the way these trucks are driven.
How you arrive at better performance is a ?????

 

I bought my '97 150 6 cyl from a two vehical Ford owner (the truck and a mustang) I noticed the intake hose was off on the 150 and asked him about it. He said that it increased performance because more air could reach the engine. I asked him why Ford engineers would build the truck to have a restricted air intake and he said he thought it was mainly to cut down on engine noise.

I drove the truck for 6 weeks and loved it. Good response and reasonable gas mileage all during that time.

My best friend at work also has a 97 150 (except his is an 8 cyl) and he loaned me his breather tube so I could do an experiment. After three weeks I pulled the joker off. It was very noticeable to me that the truck didn't have as much power and that I was having to give it more gas just to get the same performance I was used to. In my opinion, you CAN have your cake and eat it too in the form of better performance and better gas mileage.

When I gave him his hose back I told him to leave it off. I don't know if he did, I'll ask him. I also don't know if his results would be any different from mine owing to the fact he has an 8 cyl. If he has anything interesting to say, I'll post it here.

One note to all who might be thinking of trying this: Your check engine light may come on after removing the hose. (Mine did.) I waited for the computer to "recalibrate" or whatever and to turn the light back off, but it never did. After a week of having the check engine light on, I disconnected the negative battery terminal cable for about 5 minutes. Once reconnected, the light didn't come back on. That was last Saturday, 6 days ago and I'm motoring around just fine and have no plans to ever put a breather tube on my truck

 

After driving this all weekend this way, there is a faily slight improvement in mileage - about .5 MPG. As I really only drove a couple hundred miles, not a true average over a few tanks.
Speaking of opening the air breather, remember the old big blocks/ carb setups with the big round filters? People used to yank the cover off those so the entire filter would be exposed to the air instead of all the air coming through a 3 inch hole. THey stiill do this - just look at the hot rods. at car shows. I realize there is a difference between carb - fuel injection. But the engines still run on the air - the gas just explodes driving the pistons.