Mine did happen when the car was cold and between 2,000-2,500 RPM. I have an '04 with about 83,000 miles on it. Adjusting the heat shield did fix the rattle problem. Under hard acceleration I would always hear it, and I've gone 2 days now without hearing it at all.

You can kind of tell that it's the heat shield making the noise because it sounds like a metallic rattle just at a real fast pace. Sort of like fast pinging noise of metal on metal.

 

Just an update:

The noise hasn't come back and I've been back under the car to repair the stripped bolt. While under there I realized that you shouldn't really have to remove the exhaust to get at the heat shield nut that you need to tighten down. If anyone else tries this repair I would suggest trying to to position the heat shield against the bolt/nut that is most easily visible and just tighten that nut down. It should fix the problem without having to pull apart anything else.

 

I have this same problem. It buzzes/rattles when I accelerate. Very annoying. I can also hear a buzzing when I kick the front passenger tire while the car is parked and the engine is off. Sounds like something is loose. Hopefully it's just the heat shield.

 

why is that im suddenly having this same problem? For me it also occurs even if the engine is just idling, much worse when accelerating between 1500 - 2500 rpm.

 

It must be the heat. It was 90 in Minneapolis today and my car made the noise at idle. I'm really getting fed up with all the quirks this car has.

 

i can confirm that it is the intermidiate heat shaft bearing cover it was loose got it tightened and noise is gone.