Hello to all. My car has developed yet another fault. The best way I can describe it is an intermittent popping sound that occurs only at idle at about 2 second intervals. It sounds as though some sort of valve gets stuck and the sound is a result of the valve coming free. Oddly enough a friend of mine who is a mechanic says the same about a valve, probably somewhere in the airbox. Could any of you clarify what the sound is? I also thought it might have something to do with the variable length rails in the intake. I'll see if I can record the sound it makes. Thank you all for your help.