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So I have a 2002 Honda Civic LX automatic transmission. Whenever the rpms get to EXACTLY 2500rpms there is a very distinct rattle/vibration noise. It is ONLY at 2500 whether accelerating or decelerating. I have checked every heat shield, every nut/bolt, I have a new manifold/cat converter and it is still there and still at the same rpms.

I am almost positive it is not engine or tranny. I read about one guy who said he found that the exhaust pipe has a inner pipe inside? And that it can get rusty and make the rattle/vibration noise. This is making me pull my hair out, it is so annoying . This guy that said about the pipe inside the pipe, said he ran a screw in different parts of the exhaust pipe and it stopped, but I really don't know if there even is a pipe inside of it, and where to put the screws.

Has anyone else had this issue and fixed it? Or any other suggestions? Also, if I were to have new pipes installed, what kind of price am I looking at for something like that? Thanks everyone

 
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post a video of it with sound,

does it make the same noise if you rev it up while parked/standing still?

 
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It makes the noise regardless of parked, neutral, driving. Here is a video. It is not my car, or year, but it is the EXACT same noise. I would post my car, but I am out of state for a few days. It would be identical to this video though. It will only do it at 2500 rpms on the dot.

** The noise is at 11 seconds in this video**

 
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i dont have an answer, but that doesnt sound like the exhaust to me,

to me it sounds like its caused by engine vibration

 
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sounds like maybe an exhaust shield or something. Try having someone operate the car at 2500rpms and then press on stuff (probably with a stick or something) and see if you can pin point where it comes from.

On the street bike I used to have the frame sliders (which are bolted on so it's metal on metal) would start vibrating around 7,000RPM and would immediately die at 8,000RPM. Would happen no matter if you were accelerating or decelerating. But I could put my foot on it and the noise would go away. So somehow the engine/frame vibrate just right to resonate with the frame slider. So maybe it's something similar.

 
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A pipe within a pipe? It's like the Inception of exhaust systems.

I'd do what was already suggested--have someone rev the car while you're under it and start pressing stuff.

You say you've checked everything already, but don't be surprised if the noise is still coming from the heat shield (I think that's what it's called. The one that's by O2 sensor). I thought I fixed my shield several times but the noise kept coming back. It was always finding some new place to make a rattle until I just removed the whole ****ing thing. Noise stopped.

 
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When I get home in a few days ill have to look around again. I previously took off all the heat shields that I could so I don't know. Hopefully find something.

 
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Definitely exhaust in the video.

Doesn't really sound like heat shield, but may be.
Probably the resonator came apart inside, OR a double-wall pipe came apart inside.

Go under with a rubber mallet and bang on the exhaust (should be easy to get it to rattle like that), see where the rattles are loudest.