hey i got a friend with a 99 ram 2500. when he presses the gas it make a loud sucking hissy noise from the intake. we just got done changing the TB gasket and it still does it. what could it be? also when he presses the gas and then lets off the motor is still reving for a few seconds like it would rev with the pedel pressed. we know its not normal because i also have a ram and mine doesnt do it and on top of all this he's getting 6 miles per gallon. any help would be great.

 

i am interested also my truck does the same thing. i thought the hissing is normal, but mine only does it when its cold. i also only get 9mpg and the plenum is good.

 

I would have to say it sounds like the IAC is not working. This will allow additional air to be let in to the intake. Hope this helps.

 

In your particular case, sk8ordie, I don't know if you have a problem at all. Does yours still rev, even after you let off the gas? If not, but you have the "sucking" noise, you're most likely A-OK.

A K&N CAI or some sort of open element intake will make a sucking air noise, its the sound of more air going into your engine. Perfectly normal.

 

a missing, or damage tb gasket will make a sucking sound,,,,( gasket between the stock box and the tb)

 

it is really easy to not get the stainless steel clamp lined up properly
to secure stock air box to the 4 inch flange on the throttle body
because there are 'tabs' that fit into notches
and unless aligned perfectly
there will be a leak that makes a sucking noise

shine a flashlight on the clamp
on both sides looking for a tell-tale crack
and it helps to use a nutdriver
rather than a screw driver
on the tightening bolt of the stainless steel clamp

 

ya that thing is a pain in the ***, i like the way the durango's goes on so much more. plus you could put the round air cleaner on it with no mods haha

 

i made sure we put the clamp back on correctly so thats not the problem. also there is a gasket between the air box and the TB. one thing i really dont understand is why he is only getting 6 mpg.

 

o2 sensor?

maybe check the vacuum lines

 

mine is doing the same thing what fixed it or are you still having the same problem