Wierd and annoying rattling noise

[NoHachi]

Try listening and finding out where the noise comes from. Usually a little attention and a long piece of hollow tube can help you out here. At the formula student team we used to have a sort of stethoscope for these things. I remember we bought it cheaply from an ordinary carparts store. Its just a hollow plastic tube with earplugs at the end. It really helps with listening to isolated parts of the engine like bearings and injectors etc.

It could always be a bearing letting go. These tend to rattle.