Booming noise when pressing the accelerator

[wombat]

I have only had my A2 for 2 weeks. I only noticed this noise when I turned the radio off because it sounds like a single bass beat. It doesn't start happening until the engine is warmed up and only happens when I touch the accelerator. I've never had a car with a diesel engine before so don't know if its normal. But if its a fault I want to get it sorted within the 4 months warranty I got.
The trouble is, its the sort of thing that the garage will probably never hear because its intermittent and only happens when the car has been running for about 15 minutes, and they will probably think I'm just being neurotic
Has anyone else had the same thing?

[spike]

Hi wombat, welcome to the A2oc
The sound is probably caused by the EGR valve - see attached link for more details.
http://www.a2oc.net/forum/showthread.php?t=3871&highlight=mooing

Cheers Spike

[wombat]

Thanks Spike
I thought I'd searched all the forums first and not found anything. Sure I must have been the only one. Everyone is describing the exact thing. Is it just an annoying fault? or will it damage the engine?
I'll show the garage some of the replies when I go in tomorrow to collect the car - theyve had it for 2 days to get the alloy wheel sorted after I discovered it had a large crack on the inner rim
I can't believe such useful information is so easily to hand.
Thanks again