cold temps equal rough idle and loud whistling nouse
01-02-2013, 11:28 PM
#1
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cold temps equal rough idle and loud whistling nouse
On cold MN mornings (under 20 degrees), my 2001 4.6L F150 does 2 things: 1. It won't idle when first started, and 2. It has a loud and annoying harmonic whistling noise when rev'd to around 1500RPM... are they linked? What could be the cause(s)?
1. The idle issue only occurs when the outside temp dips. After starting the truck, I have to keep my foot (lightly) on the gas pedal for several seconds up to a few minutes or it will die. Then, something kicks in and it instantly revs up on its own to normal idle speed and I can take my foot off the pedal. The colder the temp, the longer I have to wait before the idle speed kicks in. I've read that the IAC may be the fault, but I've had it cleaned at the Express Lube shop (during a fuel system cleaning). How can I further test it? Or should I look elsewhere?
2. Also, when cold, their is a loud whistle/howl coming from under the hood. The colder the temp, the worse it is. Also, it only happens right around 1500RPM, regardless of whether the truck is in motion. A guy on YouTube posted a video of exactly the same whistling sound mine:
Only difference is that mine does it for a longer period of time, and higher (usually) RPM. If it's REALLY cold (at or below zero), it will whistle at 1400RPM +/_ 200RPM.
Both issues have occurred for the 3 years I've owned the truck. I took it from 104K miles to 135K miles in that time.
Are these issues somehow related? I appreciate any troubleshooting tips you may have to offer. Thanks. -Brent
1. The idle issue only occurs when the outside temp dips. After starting the truck, I have to keep my foot (lightly) on the gas pedal for several seconds up to a few minutes or it will die. Then, something kicks in and it instantly revs up on its own to normal idle speed and I can take my foot off the pedal. The colder the temp, the longer I have to wait before the idle speed kicks in. I've read that the IAC may be the fault, but I've had it cleaned at the Express Lube shop (during a fuel system cleaning). How can I further test it? Or should I look elsewhere?
2. Also, when cold, their is a loud whistle/howl coming from under the hood. The colder the temp, the worse it is. Also, it only happens right around 1500RPM, regardless of whether the truck is in motion. A guy on YouTube posted a video of exactly the same whistling sound mine:
Both issues have occurred for the 3 years I've owned the truck. I took it from 104K miles to 135K miles in that time.
Are these issues somehow related? I appreciate any troubleshooting tips you may have to offer. Thanks. -Brent
Last edited by GetMeBrent; 01-02-2013 at 11:33 PM. Reason: clarification on the issue#2
01-03-2013, 01:25 AM
#2
Senior Member
On cold MN mornings (under 20 degrees), my 2001 4.6L F150 does 2 things: 1. It won't idle when first started, and 2. It has a loud and annoying harmonic whistling noise when rev'd to around 1500RPM... are they linked? What could be the cause(s)?
1. The idle issue only occurs when the outside temp dips. After starting the truck, I have to keep my foot (lightly) on the gas pedal for several seconds up to a few minutes or it will die. Then, something kicks in and it instantly revs up on its own to normal idle speed and I can take my foot off the pedal. The colder the temp, the longer I have to wait before the idle speed kicks in. I've read that the IAC may be the fault, but I've had it cleaned at the Express Lube shop (during a fuel system cleaning). How can I further test it? Or should I look elsewhere?
2. Also, when cold, their is a loud whistle/howl coming from under the hood. The colder the temp, the worse it is. Also, it only happens right around 1500RPM, regardless of whether the truck is in motion. A guy on YouTube posted a video of exactly the same whistling sound mine: http://www.youtube.com/watch?v=JPuw4COf1eU
Only difference is that mine does it for a longer period of time, and higher (usually) RPM. If it's REALLY cold (at or below zero), it will whistle at 1400RPM +/_ 200RPM.
Both issues have occurred for the 3 years I've owned the truck. I took it from 104K miles to 135K miles in that time.
Are these issues somehow related? I appreciate any troubleshooting tips you may have to offer. Thanks. -Brent
1. The idle issue only occurs when the outside temp dips. After starting the truck, I have to keep my foot (lightly) on the gas pedal for several seconds up to a few minutes or it will die. Then, something kicks in and it instantly revs up on its own to normal idle speed and I can take my foot off the pedal. The colder the temp, the longer I have to wait before the idle speed kicks in. I've read that the IAC may be the fault, but I've had it cleaned at the Express Lube shop (during a fuel system cleaning). How can I further test it? Or should I look elsewhere?
2. Also, when cold, their is a loud whistle/howl coming from under the hood. The colder the temp, the worse it is. Also, it only happens right around 1500RPM, regardless of whether the truck is in motion. A guy on YouTube posted a video of exactly the same whistling sound mine: http://www.youtube.com/watch?v=JPuw4COf1eU
Only difference is that mine does it for a longer period of time, and higher (usually) RPM. If it's REALLY cold (at or below zero), it will whistle at 1400RPM +/_ 200RPM.
Both issues have occurred for the 3 years I've owned the truck. I took it from 104K miles to 135K miles in that time.
Are these issues somehow related? I appreciate any troubleshooting tips you may have to offer. Thanks. -Brent
Take the belt off, and see which item makes noise when you turn it. It should be easy to find. Good luck
01-03-2013, 01:26 AM
#3
Senior Member
Check the IAC and clean it for the idle when cold. That usually fixes the idle. Has for a few of the guys lately with the colder weather. Again, good luck.