I’ll throw in my unwarranted & relatively ignorant 2c worth in here. Please bear in mind that I’m on the steep end of the learning curve regarding diesels – I’ve owned mine for less than a month.
From my understanding, the ALDA functions as an altitude compensation device. Technically, it would be referencing the deflection of the sealed chambers/bellows inside of the ALDA to determine actual atmospheric density. Knowing this, and after studying the images of the (internal) linkages on the service CD, it would seem logical that the ALDA will affect mixture throughout the RPM range. On a non turbo engine, it would be strictly for altitude & weather compensation. On the turbos it detects manifold pressure as an increase in atmospheric density, and enriches the mixture appropriately.
Once again, caveat emptor… Sometimes free advice is only worth what you pay for it.
At least if the advice comes from me!
There are others on these forums that really, REALLY *REALLY* know their stuff… (I’m trying not to name names, but they know who they are)
P.S. When you say that you “maxed out” your ALDA setting, how many turns did you move the screw? And what is the result of this? Are you now hiring out as a mosquito abatement contractor? Just kidding, but let us know.