cleaned IAB...now it has harmonics!?

[musiccitysho]

My 93 ATX had a start and stall condition,with no CE light or codes. It only happened twice though when it did it would continue to start and stall until I reset the memory. I narrowed it down to most likely the IAB being the culprit.
I pulled the IAC and cleaned it w/ carb cleaner, along with the nostrils in the intake.
Everything went ok until I started the car and reset idle speed. It now has a howling hum at idle which at first seemed to be coming from the aibox (I thought maybe a vacuum leak) but as I followed it to the source it is the IAB. It did not make the sound before.
Did I fry the IAB solenoid w/ the carb cleaner, it still seems to be functioning just w/ an annoying loud buzz/howl.
I did a search and only found posts about existing hums from the IAB none about it happening right after cleaning and reinstalling it.
Thanks for any insight
Steve M

 

[AutoSHO]

All SHOs have a loud hiss when cold from the IAB, is that all yours is, or does it make another unusual noise?

 

[musiccitysho]

No its a different sound, like when you blow over the opening of a bottle. It stops when the idle is just over 1000 rpms and resumes again at 900 rpms. It didnt do it before I pulled things apart.
Thanks for the quick response!
Steve

 

[musiccitysho]

Also I thought of it just being cold so I took it on I-65 and opened her up WOT and got the engine good and heated. When I got back off and at stopped at a light it still was howling at idle. When I got home I checked and the sound is deffinately resonating from the IAB unit.
Performance is great and idle is perfect just noisy!

 

[AutoSHO]

That is really weird. Try loosening the mounting bolts on the IAB and jsut repositioning it a bit. I have never heard of anything like this before!

 

[MotoArts]

My '94 ATX makes a similar noise to the one you describe also. Goes away when I turn on the heater. I haven't tried to chase it down yet.

 

[projectSHO89]

You have what is called "moosing" on a 2.5L Duratec used on the Contour and Cougar. The fix for those engines is not available for the SHO engine, however.

You can try adjusting the position of the IAC valve on the intake, however the only sure cure is to replace the IAC.

FWIW, my 5.4L Lincoln Navigator is just starting to exhibit intermittent moosing.....

Steve

 

[Off Road SHO]

Steve,

I think Chris is on to somthing there with the repositioning. IIRC there is a blind hole in one of the parts. May be that hole is now open to air flow and is getting that "blowing across the pop bottle" sound.

Tom

 

[musiccitysho]

Thanks everyone for the help. Turns out that it resolved itself. I started it up this morning and the "howling" was no longer present.
The only thing I can think of is that some of the carb cleaner hadnt fully evaporated before I put it back on and was making the piston resonate through the throttle body, or that when I cleaned the nostrils some carbon buildup temporarily blocked an airway.
Good news for me, Thanks again for your time and advice
Steve M

 

[twr]

I had a 93ATX do that to me after cleaning the IAB and EGR nostrils. Very weird noise and I could feel it. It was the IAB, because when I unplug the connector, the noise went a way. I cleaned it again and it went a way.

<small>[ February 18, 2004, 04:39 PM: Message edited by: twr ]</small>