# 1999 ford expedition 5.4L humming

**URL:** <https://community.cartalk.com/t/1999-ford-expedition-5-4l-humming/79387>\
**Category:** Maintenance/Repairs\
**Created:** [May 18, 2013, 6:26pm UTC](https://community.cartalk.com/t/1999-ford-expedition-5-4l-humming/79387 "2013-05-18T18:26:15Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![kparchment](https://avatars.discourse-cdn.com/v4/letter/k/ac8455/32.png) [@kparchment](https://community.cartalk.com/u/kparchment)\
**Post date:** [May 18, 2013, 6:26pm UTC](https://community.cartalk.com/t/1999-ford-expedition-5-4l-humming/79387/1 "2013-05-18T18:26:15Z")

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I have been hearing a loudish (I can hear it in the cab) humming noise coming from the engine bay. I don’t hear it when the truck is cold (1 to 5 minutes after starting), seems to get louder at it its peak (the more I drive). When i open the hood, the humming is coming from the intake. I am a pretty handy guy, just at my witts end right now…not sure, but I was thinking brake booster? HELP!!!

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [May 18, 2013, 7:15pm UTC](https://community.cartalk.com/t/1999-ford-expedition-5-4l-humming/79387/2 "2013-05-18T19:15:21Z")

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Does the humming occur only when the engine is idling? Or does it occur at all times?

Tester

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**Author:** ![asemaster](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@asemaster](https://community.cartalk.com/u/asemaster)\
**Post date:** [May 18, 2013, 9:56pm UTC](https://community.cartalk.com/t/1999-ford-expedition-5-4l-humming/79387/3 "2013-05-18T21:56:11Z")

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If the noise is only there at an idle, it could be a faulty Idle Air Control valve. Look online for a picture of one, then find it on your engine. Put your finger on it when you heat the noise, if you can “feel” the noise you’ve found the trouble.

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**Author:** ![kparchment](https://avatars.discourse-cdn.com/v4/letter/k/ac8455/32.png) [@kparchment](https://community.cartalk.com/u/kparchment)\
**Post date:** [May 24, 2013, 8:15pm UTC](https://community.cartalk.com/t/1999-ford-expedition-5-4l-humming/79387/4 "2013-05-24T20:15:05Z")

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I only hear it at idle but I am assuming it drowns out once the engine noise kicks in.

Its not the IAC Valve, I replaced that a month ago