New IAC CAUSED howling noise | Ford Explorer Forums - Serious Explorations

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New IAC CAUSED howling noise


Active Member
March 23, 2008
Reaction score
City, State
Atlanta, GA
Year, Model & Trim Level
Explorer Sport '99
I've seen a bunch of posts regarding old IAC's causing a howling noise, and cleaning/replacing made them better; however, I just installed a new IAC and now I have howling at idle when I didn't have it before.

I bought the cheapest one, duh,
at RockAuto. Has anyone else had this problem.

FYI I noticed that my replacement came with a gasket shown in the second picture in the link. My old one did not have a gasket on it. I installed it thinking that it should have been there in the first place. Could this be the cause? is this new IAC bad?



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Did the gasket look like this one? This is the one that your 99 SOHC should use.


Negative, but I've got the OHV and the gasket looked like this


Interesting, I just looked at Rock Auto for an IAC gasket and it showed this for the '99 V6 OHV:


Howling went away on its own. I guess something broke in.

Some air filters will cause this also. Ours howled, but went away with a new air filter. Seems to be a reed type action going on in there somewhere-I think it is the rubber seal inside the iac which actually vibrates.

That sounds pretty likely. I'm pretty sure I messed around in the airbox after noise and never made the connection that that was the fix.

new IAC

I have a 2000 Ford Explorer. It started howling on me as well. When it first started doing it I could unplug the MAS and it would stop. After a while that did not work anymore. I replaced the IAC from a new one that I bought on ebay and that made it worse. I put the old one back on it and that put it back to where it was befor. If I unplug the IAC while it is running the noise goes away and the idle drops considerably. I can rev the engine up in this state and still get no noise. I will try another IAC when I get one to see if maybe I bought a faulty IAC. Also the gasket you mentioned I tried with and without the gasket and it seemed to make no difference.