Howling noise

[MD Ever]

So I finished up all the work on my car (60k, rod bearings, etc) and I started it up. Everything sounded beautiful! Then it got warm and at idle it was making this howling sound. If you bring the idle up just slightly the noise is gone. I wasn't sure where it was coming from at first but the TB hose and air box seemed to be vibrating when I put my hand on it. I opened up the air box and the noise was real loud. Its coming from the intake. If anyone is familiar with the hooting noise that the 4.6l made from the IAC back in the late 90's/early 00's, it sounds like that only constant at idle. If the A/C kicks on or you turn the wheel the noise goes away. That's how little the rpms have to be raise to get rid of the noise. So what did I screw up?

 

[cmz829]

wow i am having the exact same problem i am also wondering what the problem could be i suspect that the problem is a chip in my cold air intake from a accident my car was in i can also feel the vibration to touch on the airbox

 

[MD Ever]

It's the IAC. I just figured it out this morning. If I disconnect the IAC and bring the rpm up to normal idle the noise is gone. I tried repositioning the valve and it kinda worked. It just moved the howl to a slightly different rpm. I guess I'll just get a new one. I tried cleaning it and I think that is what caused the noise in the first place. It will be a while (ran out of money) but I'll let you know how it goes.

 

[cmz829]

i also have a occasional CEL that will come on for a minute or so and when this happens my idol goes to about 1600 in park i wonder if this is what is causing it

 

[SHObill]

Clean the IAB(IAC) & all ports in the intake & TB.

 

[93rev2sev]

Are you sure thats the howling? Is the timing belt too tight?

 

[MD Ever]

Clean the IAB(IAC) & all ports in the intake & TB.

If you were talking to me I already did that. My intake is spotless, including the nostriles and I cleaned the IAC. I think that's what caused it to start making noise.

Are you sure thats the howling? Is the timing belt too tight?

It's an atx. Besides, when you remove the top of the airbox the noise gets hideously loud.
I'll get a new IAC in a week or so and let y'all know how it goes.

 

[cmz829]

did you get a chance to get the IAC yet? please update when you do thanks

 

[MD Ever]

Well, funny thing. The noise is gone. I've put a couple hundred miles on it now and it isn't doing it anymore. Maybe something got stuck in it when I cleaned it and it worked itself loose. Not sure. It's one of the only parts I didn't replace during this rebuild though so if it comes back I'll do it then. Sorry I couldn't be more help but if the noise seems to be coming from the throttle body area like mine was try what SHObill recommended and clean it first. Good luck!