It's an acronym for a long German term (or terms). I don't recall offhand what that is. I know the non-turbo models have an ADA (no "L") which compensates fuel delivery based on altitude only. The ALDA adjusts for both altitude and boost pressure.

Is anything dragging like a caliper or the parking break? These cars are sensitive to that.

When I got my TD it wouldn't go over 50. It had been sitting for two years. After about a week of "Italian Tuneups" it started getting better. I think the turbo was not spooling up after sitting for so long. Large amounts of smoke on acceleration. Sprayed WD40 on every bolt and in every nook and cranney by the turbo expecting to have to take it off. But it just kept getting better.

However, in the last 20,000 miles (8months) is has run great. I have not used diesel purge yet but will shortly. I still get a few erratic shifts from time to time but I think ehere are a few vacuum leaks, like in the pods under the air cleaner.

Hope you find your problem. These cars are great when the run correctly!

Joe

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www.jerseyplanning.com
1987 300TD 440K - My car
2005 Jeep Grand Cherokee Laredo 107K - Tim's car
2000 - CLK320 100K - Deb's car
1994 C230 150K - Josh's Car

"Hmmm. Will it rev to 5000rpm in park? Floor the pedal and listen, it should scream away (don't worry, it's governed, just don't hold it up there for more than a couple of seconds.)"

This reminds me of a funny story. I was 17 at the time and worked at a dealership as a car jockey. I had to move a shiney new Avanti and noted the tach says something like 6000 RPM. So, in neutral, i floored it peddle to the metal and held it and watched the pegged needle. after a short period, I heard a loud bang and everything came to s stop. I called the mechanic and told him the engine stopped (I didn't tell him what I did though).

He later asked what the hell did you do all the belts came off? I said with a stupid grinn: "nothing"

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

bear with me because I will probably ramble in this reply.

Purchased my first MB diesel last october, with no prior knowledge of such cars. I drove it home and thought to my self "this car is slow and the trans mission shifts funny, but I guess its an old diesel so oh well"

Then I got on here and started reading about the 1987 300D's and the ability to hit 60 in the 10 second range, I was closer to 30 so I started pokin around.

I thought maybe it was a power issue so one day after reading a bunch on here and realizing that my trapox had been replaced I started to play around.
* I made sure the turbo spun freely and had no play.
* I replaced my fuel filters
* I did some reading and tracing and found that someone had already disabled the EGR and done it somewhat propperly.
* Cleaned boost lines to overboost protection solenoid and ALDA.
* Checked vaccum all over the place with my guage on my Mity-Vac.

Everything looked great and the car started better that newer diesel trucks I've owned and idled absolutely smooth and so quiet.

after a few adventures I was unable to find any power and still had long hard shifts.

I let a friend that is a diesel truck mechanic look at it and drive it around, he said he thought the car ran great for 300K miles and that he thought if we adjusted the throttle valve cable up tighter it would rectify some of the shifting issues and would kick down earlier and make it feel more powerful. I didn't let him touch anything because on advice from this board and some of its members in sidebars I thought the car should run better.

Frustrated, I dug the boost guage out of my Cummins powered truck and rigged it up to a T in the line going to the overboost solenoid.
I was seeing maybe 2lbs of boost at max load going up the road in 2nd and 3rd gear. OBVIOUSLY THERE WAS A PROBLEM.

Confered with some other board members and decided it could be a clogged cat and that I would lose only the time taking it off to check it out. Took the down pipe off and just left the exhaust exiting the turbo. The boost guage instantly hit 12+ psi when we left the driveway with my foot on the floor and every issue with power and shifting went away. The car accelerates like a 603 with un-molested ALDA should and shifts better than any other automatic car I've ever owned.

I'm not sure if my shifting troubles were the same as yours but you may want to check the cat. Boost and power expected by the tranny due to the vacuum signal it is receiving obviously affects how it shifts.

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87 300D Turbo (still wondering about #14 head)
98 Buick Regal GS (one quick grocery gettr)
07 Honda CBR1000RR
04 Dodge Ram Laramie 4x4 CTD (heaven)
95 Dodge Ram 3500 CTD. Need snow plowed?

Muleers,

Did you ever check boost pressure?

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1990 300d 2.5 new to me.