Loud intake noise suddenly

[BigCars4Ever]

About a month ago car started to have idle problems. It was bad when cold and got better when the car was closed loop but still rough. I replaced the IAC solenoid and that made it better but not fixed. I figured the car needed time to learn. Drove today to get gas and the woman at the pump kept looking at my car with a puzzled look. I turned the radio off I I could hear a lot of intake noise like a small trumpet was stuck in my intake. Idle was good. I think I may have gotten a bad IAC but is there anything else that could cause this? Car had 140k on it. This is the first thing I have replaced on the intake. Still original EGR, checked the PCV valve and it was clean and free. Not sure what else to try.

[SilverPhoenix]

I can't recall what this part is called, but it gave me problems similar to yours and then after a couple weeks my car wouldn't start at all. Might not be what your issue is, but maybe something else in that area...

[RubberCtyRauder]

Any codes,CEL ? Whistling could be vac leak, air intake leak. Whistling can also be a pulley,idler. Kinda sounds like a centri unit. Does sound pitch change with throttle?

[BigCars4Ever]

No codes, No cracked or broken hoses. I did a live data scan and I see that the IAC is in learn mode which makes sense but it is at 50% activation which I think is normal. The only issue I see in the data stream is one of my O2 sensors is going bad. I may buy another IAC and this time go for the Motorcraft part and see if that fixes it. Bought an aftermarket last time.

[justbob]

Check the vacuum lines under the throttle body.


Sent from my iPhone using Tapatalk Pro

[BigCars4Ever]

I did some searches and the Mach 1 boards all agree that all of the aftermarket IAC's trumpet. I dropped the money on a Motorcraft replacement. Will update once installed.

[BigCars4Ever]

Got the Motorcraft IAC today and swapped out the no name aftermarket and presto...noise gone and idle is smooth.