I decided to take apart the air intake system to decoke and hopefully improve idling etc.

I knew there was a butterfly flap between the air filter and the EGR valve but I also discovered two more , one underneath the cross over and another where the crossover meets the intake manifold. The one under the cross over was completely stuck and would not move until I cleaned it.

Can anyone explain to me what these three butterfly flaps are supposed to do and in what circumstances do they open

I also noticed that the large one just before the EGR seems to be slightly open by default - is this correct?

I took some pics for reference if this helps:
http://photos.wanadoo.co.uk/album/1414673

thanks in advance
Keith

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Keith

1995 E300D auto Wagon