Resonating Noise at 3000rpm

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I have a reciprocating/resonating wavy bass sort of noise at 3000rpm and above. rav4 2003 2.0L. No vibrations, no ticking noise. The noise isn't that loud, but consistent. Checked engine mounts all good. Checked for any loose heat shields all good. Right when I let go of the gas it goes away, even at 2900rpm. It sounds related to intake or exhaust.
 
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5,005
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the canyons
I'd check the entire exhaust system routing. I'd place strong odds on the exhaust system having rotted out somewhere along it's length, and the pipe is now resting against something and resonating.
 
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Originally Posted by gathermewool
Irrespective of vehicle speed?
While holding the throttle open at 3000 rpm or above, it starts. I let go of the gas/throttle a little and it stops.
 
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Originally Posted by 02SE
I'd check the entire exhaust system routing. I'd place strong odds on the exhaust system having rotted out somewhere along it's length, and the pipe is now resting against something and resonating.
Thanks, good idea.
 
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A baffle in a muffler can be loose as well as the inner guts of a cat converter. Idler/ belt tensioner may be worn (accessory or timing belt). Loosen/remove accessory belt and bring it up to the RPM that the vibration is happening. Some vehicles are engineered such that the torque converter can be separated from the flex plate so that can be eliminated as a source for the vibration. Sometimes vibrations are tough to isolate....
 
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217
Location
Toronto
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Originally Posted by 02SE
I'd check the entire exhaust system routing. I'd place strong odds on the exhaust system having rotted out somewhere along it's length, and the pipe is now resting against something and resonating.
Thanks, good idea.
Originally Posted by PontiacHO
A baffle in a muffler can be loose as well as the inner guts of a cat converter. Idler/ belt tensioner may be worn (accessory or timing belt). Loosen/remove accessory belt and bring it up to the RPM that the vibration is happening. Some vehicles are engineered such that the torque converter can be separated from the flex plate so that can be eliminated as a source for the vibration. Sometimes vibrations are tough to isolate....
Good idea with the belt/tensioner pulley. The vehicle does make a squeaking noise when started up but eventually goes away. I traced the squeaking to the belt/tensioner pulley, which I will come around to replacing. But I don't really know if this noise is related.
 
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217
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Toronto
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Originally Posted by Olas
your description first made me think exhaust drone - second place I went to was a wheel bearing noise. does it make the noise in every gear?
Definitely not wheel bearing noise. I did replace the front wheel bearings. This noise was pretty much there since I bought the vehicle.
 
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Toronto
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Originally Posted by Olas
your description first made me think exhaust drone - second place I went to was a wheel bearing noise. does it make the noise in every gear?
Drone noise from exhaust could be it.
 
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Thanks for all the ideas, I will look into them I don't know why but the noise kind of sounds like it's coming from around the throttle body area, but I checked and don't see anything wrong there. No vacuum leaks or anything.
 
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Is this noise, drone, or vibration detectable at the RPM noted while sitting still or does the car have to be moving? Does it have an electric cooling fan or mechanical fan (fan clutch)??
 
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New England
Originally Posted by tookien
I don't know why but the noise kind of sounds like it's coming from around the throttle body area, but I checked and don't see anything wrong there. No vacuum leaks or anything.
is your intake stock, including any resonator? A popular mod with the Subaru community (at least with older Subarus), is/was to remove the intake resonator, affectionately called the snorkus. It was supposed to make the intake sound more pronounced. After removing the snorkus in my previous STI I found that it resulted in a deep womping at certain engine loads, along with another unusual suction sound when I first got on the throttle, but before the turbo spooled. The air box in most Subarus is pretty easy to get at.
 
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Has the air filter been replaced lately? An ST air filter at Walmart would be a good choice for $11. Made a big difference when I replaced it in a car similar to yours. The old Fram had about 40k on it but didn't look too bad. Glad I changed it.
 
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