Engine shutters and gets loud at low speeds?

2008 FORD F-150
200,000 MILES • 4.6L • V8 • 4WD • AUTOMATIC
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BBEAR41
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Particularly coasting up to a stop light or in reverse i can feel a shake and it wants to stall and is loud. I'll give it gas in neutral or with brake on and once it gets close to 2,000 RPMs it quiets down and idles. It will idol around 500 but used to be 900.
I ran liquid moly engine flush. Did an oil change with full synthetic and added engine oil saver. That helped about 50%.
My mileage is 210k kilometers. Not sure what miles it translates to.
Jul 18, 2023 at 11:17 AM
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JACOBANDNICKOLAS
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Hi,

Often times a rough idle is caused by an engine vacuum leak. Have you checked for any? If not, start with that.

Here is a link that explains how to find one:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, is it possible for you to record the noise you mentioned and upload it for me to hear? That has me a bit confused. Also, let me know if once you it is off idle if it runs normally or has a power loss.

Let me know,

Joe
Jul 18, 2023 at 9:28 PM
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BBEAR41
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Sorry for the late reply. Here's a video of noise.
Video (Click to enlarge)
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Sep 19, 2023 at 6:55 AM
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JACOBANDNICKOLAS
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Hi,

I certainly heard it. To me, it sounds like top end noise from lifters, camshafts, or something on top. Is the engine oil pressure light turning on when it makes this noise?

Take a look through this link:

https://www.2carpros.com/articles/engine-noises

Let me know about the oil pressure at idle.

Take care,

Joe
Sep 19, 2023 at 8:32 PM
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BBEAR41
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No. No light of any kind comes on.
Sep 19, 2023 at 9:01 PM
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JACOBANDNICKOLAS
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Hi,

It does sound like top end engine noise. Is it louder at the top of the engine near the valve covers? With it running, can you tell approximately where it is coming from on the engine?

Also, even though there is no light coming on, you may want to consider borrowing a mechanical oil pressure gauge from a parts store and check the pressure using it. It will screw into the same location as the electrical one does.

I attached the pressure specs below.

Let me know.

joe

see pic below.
Image (Click to enlarge)
Attached Media
Sep 19, 2023 at 10:03 PM