what is LDA unit? (1.6TD)

[slowbus]

On a recent camping trip, I was inspecting my engine one morning (as you do), and I noticed a hose sitting loose on top of the engine. I quickly fiund that it had come off the canister sitting behind the injection pump. I have since found out that this is called an LDA unit and it has something to do with the turbo. Now I was wondering, as I have no idea how long it had been off and I haven't noticed any difference with the running of the engine since I replaced it. What does it do
Thanks
John

[madjak]

This alters the amount of fuel the injection pump puts out as the revs rise through the middle and higher rev range. No idea why it would have been disconnected.

[slowbus]

Thanks madjak