MK1 MR2, Funny noise at 3400rpm. Any ideas?

[cooper_ed]

My car has started to make a noise like a piece of metal scraping along the road whenever it goes through 3400rpm (approx). If i sit at 3400rpm, it doesn't make it constantly, and it doesn't make the noise when not under load. Its not a mechanical crunch type sound, more if a higher frequency scrape?? And it only lasts a second at the most, anyone got any ideas,
ps. I have checked under the car for anything dangling.
Cheers, Ed.

[trooper1212]

Sounds like it could be the exhaust resonant frequecy so it rattles on the body at that point.

Techincal solution is to get it on a lift, give the exhaust a bang with a big stick and use a crowbar to reshape it wherever it hits the body.

[Munter]

Have you checked the exhaust manifold heat sheild is still attached firmly?

[cooper_ed]

I have had a look, and found a couple of small stones lodged in the back of the clip on style tailpipes that the stock exhaust system has {I promise they were on the car when I got it and they are not bolt on boy burberry-tastic add-ons!}. Anyway, I have now removed them, but have now had a chance to test fully. A quick drive around the block would indicate problem solved. Cheers lads.