What's An ALDA?

I've seen the acronym "ALDA" bandied about here and on the mbz.org mailing lists hundreds of times, but no one ever defines it or explaims what it is. I've been driving diesel
Mercedes for over six years now, and have owned four of them, and I still have no clue what this mysterious widget is or does.
I admit my ignorance and throw myself on the mercy of this 'ere fine forum. Please, I beg of you: WTF is an ALDA?
Geoff
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"'The meek shall inherit the earth?' Not on *my* watch!"
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Google was no help in finding a definition but did find a picture of one:
http://articles.mbz.org/engine/diesel/alda /
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Actually this was quite educational because I now know that Alan Alda is 70 years old which makes me feel very old.
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Geoff Miller wrote:

Maybe because they don`t know what it stands for?

ALDA = Atmosphaerische Ladedruckanpassung A tmosphaerische LaDedruckAnpassung
Roughly translated = atmospheric charging pressure adaption
I've also seen it being referred to as _Barometric Pressure-Charge Air Pressure Compensation _
Juergen
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It is a device attached to the injection pump that increases fuel delivery when turbo boost is generated from the turbo to make more power. If additional fuel is not added, additional power is not realized. It works by allowing two aneroid capsules to compress (collapse) under pressure allowing a spring loaded rod from the injection pump to extend, adding additional fuel.
These are sometimes adjusted to add additional fuel and thus create more power, however sometimes adjusting them will cause permanent damage. They are optimized from the factory with a good balance of fuel economy and power therefore I recommend not altering it. They should have a plastic seal with a metal band around the adjusting screw on top that is a seal applied when the pump is on a test bench, and it is on there to discourage adjustment. If yours has been removed then it has probably been adjusted previously. If your car is running properly then the power under full boost is not changed much if any at all.
Jeff

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Ditto, especially about NOT messing about with the ALDA for it can be broken and is NOT readily available as a repair part.
If you want to see the effect it has just test drive the car with the plastic lint to the back of the intake manifold disconnected (Pocket the hollow bolt and don't mind the hissing sound - its harmless).
Incidently the ALDA is at the top rear of the injection pump: square with a circle that hold the brass spheres.
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