I hear the sound of air moving (kind of a whoosh sound) coming from under the dash on the passenger side. It seems to get a little quieter as the truck warms up.
Maybe a vacuum leak or just the sound coming from under the hood?
It is a 2001, 4x4, 4.0, Auto, Super Cab with a K&N intake and Magnaflow exhaust.

Has anybody ever heard of this?

 

I have no idea what might be causing it, but vacuum leaks are almost always accompanied by a CEL light because it causes the engine to run lean.

 

well if it was a vacuum leak it would have something like a high idle or along the lines with that i dont think it would be a vacuum leak

 

Yeah, I wasn't sure about the vacuum leak. I don't get any CEL codes. What should the idle speed be?

 

its the underpants gnomes again

 

i THINK IT SHOULD BE AROUND 750 800?

Sorry about the caps haha

 

850 to 900 and if your moving around 1000 to 1100, mine is old and acts a lil funny but keeps to those numbers most of the time

 

Mine is usually around 1100 - 1200

I need to double check it just in case the needle is off.

 

Additional info:

I can hear the sound when it's cold. When I put it in gear it gets much louder. It is quieter when in park or neutral. Once it warms up it is gone.

When the hood is open the K&N intake sounds pretty loud cold or hot. I don't know if it has anything to do with it, just thought I should mention that.

 

Intake or exhaust leak.

 

I guess it's you IAC acting up.

If I'm not mistaken it uses PWM and if the piston to bore clearance is out of spec you can get those noises.

Rich

 

Injectors use PWM (Pulse Width Modulation), I'm not sure about the IAC. DC to DC voltage regulators also use PWM.

 

On another forum (yes there are others) someone said to remove the connector to test the IAC.
when I pull the connector off, the motor wants to die until I put it back on.

Is this any way to test the IAC?

 

Anybody know how to test the IAC? I don't want to buy a new one if I don't need it.

 

Sounds like your IAC is working. It still could be making noise though.

 

yea its definately not the iac

 

Looks like my tach is off. The tach says 1100-1200 but is actually 700