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Discussion Starter #1
What is the source/cause?

Motor mounts. Check.
Belts. Check.
Pulleys. Check.
Crankshaft harmonic balancer. Check.
Engine. Check.
Transmission. Check.
Electricals. Check.
Blower motor. Check. (And doesn't matter if it's on or off.)
Suspension. Check.
Brakes. Check.

Ask away.

'99 2.0L 4dr AT.
 

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need to start isolating the vibration. Remove the drive belt and run it. Is it still there?
 

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Is it a low F# on a flute, or a high F# on a trombone?
Or a reedy F# on a bassoon?
 

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Anyone have it figured out before I reveal?
How can we figure it out when you do not tell us anything.

Motor mounts. Check.
Belts. Check.
Pulleys. Check.
Crankshaft harmonic balancer. Check
Engine. Check............
Transmission. Check.
Electricals. Check.
Blower motor. Check. (And doesn't matter if it's on or off.)
Suspension. Check.
Brakes. Check.

How did you test these things and what were the results? You don't tell us anything and you expect us to know the answers.
How about providing something useful like........My first suggestion. Is the noise there with the drive belt removed?
How about this..........Is the noise there with engine running in park or only when moving? If moving is it there at all times?
Give us something to work with.
 

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I see now this is an exercise in futility.
 

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So, a fairly high pitch
Does it matter if the engine is on?
Vacuum leak in the brake booster comes to mind.

p.s. I see there are several posts by one or both of the people I "ignore", so I can't see them.
I presume I'm not missing anything.
 

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Discussion Starter #10
So, a fairly high pitch
Does it matter if the engine is on?
Vacuum leak in the brake booster comes to mind.

p.s. I see there are several posts by one or both of the people I "ignore", so I can't see them.
I presume I'm not missing anything.
I like your thinking. You're heading in the right direction.

Actually, it wouldn't matter if the engine is on or not.

p.s. And, no, you're not missing anything.
 

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So it does this when the car is completely shut off?
Makes me wonder where the energy to make this happen comes from.
(My belief is that all activities in the world are driven by energy, fear, or money.)
So with the car off there are things that still get electrical energy, like radio, clock, engine computer etc.

Does this sound come and go randomly? How long does it last?
 

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Discussion Starter #14
You are rapidly approaching it. You are absolutely correct on the energy. The sound does not come and go randomly. Bear in mind, the frequency is always noticed when driving. Originally, it always occurred at 18 MPH and was sustained from there. It always begins with a crescendo. The F# begins, and its amplitude increases (briefly) and then steadies throughout further acceleration. The dash comes alive with the resonance. It's all across the dash. And, the resonance moves about the dash. The electricals have nothing to do with it. Neither do any of the other parts of the car that were tested and ruled out in the original post (#1). It lasts until just before the car comes to a stop, though it also can (and did) happen when stopped.
 

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Doesn't originate under the dash methinks.
Something rubbing...
Like a bow across a viola string?
Like a rusted, loose back-shield against a brake rotor?
OTOH, does this have the old style speedometer cable?
 

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Discussion Starter #17
You're sooooo close. (Yes, I had chased the brakes/shields/rotor and old style speedo also.)

The reveal:
There is a long thin string of silver tape sheathing that runs across the windshield's top moulding - covering a similarly sized metal strip. After 21+ years, the tape sheathing (and not the moulding) began separating from the strip, but remained tight against the strip. This enabled the string to vibrate as the car was driven as the aero worked up and over the hood and ran up the windshield directly to the string. Its frequency was the F#. As those waves entered the car (including via the ducting), they bounced off the long gray metal (pipe organ) tube that runs the entire length of the dash. This tube, coincidentally, is tuned at a B natural. The F# is the 2nd order harmonic of B natural. Anyway, the dash came alive with resonance. As the string began to loosen further, it still remained tight against the strip, and remained fastened at various places. As a result, a second frequency was generated along a different sub-string. A G# (above). And, the dash would sing F# and G# separately and together, with the dash resonating and vibrating all over the place and all the way across. Thus, it was not possible to pinpoint a singular location. The resonance moved about. When the car was stopped, it happened to be facing the strong winds that occurred earlier this week. The dash came alive with resonance and vibration - just sitting there.

The story on how I finally figured it out is one of those good ones. But, it takes 5 full minutes (or more) just to tell it. In the end, I was not in the car, but I was not out of the car either ... and had I not done that, I still would be chasing it …

Thanks for your interest. You headed down the right path from the get go. Nice work.

Here are the pics.

20200415_143502.jpg 20200415_143633.jpg 20200415_144202.jpg 20200415_144441.jpg 20200416_140516.jpg

Looks like the thumbnail pics are too small. Here is the string full image.

20200415_143633.jpg
 

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What stupidity.
 

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I can just imagine Peter Schickele in his heyday rolling this car on stage to use in a P.D.Q. Bach piece.
Now I must ask: what's your primary axe? Mine's tenor sax. (no rhyme intended) :cool:
 
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