On the contrary. The ALDA is designed to make your diesel run better. It functions as an altitude compensator and can be adjusted lean or rich, depending on present elevation. From what I've learned, the turbo wastegate setting and its concomitant ALDA setting are calibrated on the conservative side as your diesel benz leaves the plant in Stuttgart. The turbo delivers a modest 7-9 lbs of boost, and the IP sends an appropriate amount of fuel to be burned.

With some careful tinkering, the wastegate and ALDA can be adjusted to yield more horsepower in the 617 (and other?) engines. I've done this on my '84 300D, and the results were pleasing; I get quicker turbo spin-up and a bit more pep off the line...all without fuel efficiency suffering.

If you attempt something like this, mind two important caveats: monitor the amount of boost from your turbo by tee-ing a gauge into the line that goes to the switchover valve, and be very careful when adjusting fuel enrichment on the ALDA; they can break without warning. Remember to turn CCW for rich adjustments...in 1/8 to 1/4 increments.

If done correctly, you will be amazed at the increased performance.

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Matt
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1995 E300 Diesel (Die Blau Frau)