2000 E430 ticking above 2k rpm, under load?

[smjfreeman]

Hi all!

The car: 2000 E430 Estate, 130k miles, runs lovely. Everything works

What wrong: About a week ago, I noticed a ticking noise with the following characteristics:

1. It sounds like its behind the drivers side vent (right hand drive!)
2. It only appears under moderate to hard accelleration
3. It only appears above 2000 RPM, and tends to go away at higher RPMs (although the latter is intermittent).
4. At full throttle/rpm it doesnt seem to be there at all
5. It is not temperature dependant whatsoever.
6. It IS dependant on throttle opening, suggesting intake/exhaust leak - but I've had that checked, theres no apparent leak.
7 Despite 6, the ticking sounds like one cylinder
8. Power is completely unaffected.

Thats as much as I can remember. Has anyone got any ideas on this?

Kind regards,

Mike F
Devon UK