2003 with the 4.7
When the truck is cold and is started it sounds like it is sucking a lot of air. When the engine comes up to temp that sound goes away and it get low and throuty. That is not happening now. It sounds like a stuck choke but it does not have a carburator. I reset the computer by disconnecting the battery and while it was learning idle it did better but now the sound is back.

 

Rad fan?

 

Just replaced the fan clutch. Not because of this problem. I had to change a water pump so I changes the fan clutch and thermostat while I had every thing apart. when the truck is cold is sound like a lot of air is getting moved around or bypassed. When the engine comes up to temp that usually goes away but it does not know. It does go away at low idle but when you step on the gas it sounds like it strugles and looses some power but the rpms are fine. Just sounds like it is sucking crazy amounts of air.

 

breather hose on the airbox maybe.
i left it off once and it did that.
i'd check all vacum hoses too, if u havn't.

somone smarter shoud chime in.

 

Take off the clutch fan and get back to us.

 

if its a roar, its the fan clutch.

if its truly an air sucking sound, you have a vacuum leak. Check hoses for cuts, bends, loose etc.

 

Could your throttle body butterfly be sticking open a bit?

 

Thanks for the help. It was the new fan clutch I had just put on that was bad out of the box.

 

You're welcome .

 

You don't really need your clutch fan, so if it's bad, you can take it off and leave it. Plus you will free up a couple hp, and might gain a mpg...