Adjusted the ALDA last night, it shifts soooo much smoother now.

To keep a long story short, it has been soft in the pedal until the boost kicks it around 2000rpm or so. Starting off slowly would give me a real kick in the seat 1-2 shift, and the 2-3 & 3-4 were a bit harsh also. In the rain the 1-2 shift would sometimes get me sideways, kind of embarrasing.

I checked the vacuum, no leaks no problems. Shifts fine above 1/2 throttle, except for the 1-2. I've changed ATF twice this year, hoping that synthetic would help, no change.

I have resisted turning the ALDA because I was afraid more power would be more thump, and I'd like to keep the transmission together. I also wanted to keep the car as original and stock as possible, it has lasted this long in near-perfect original condition and all, ...

I have considered adjusting the Bowden cable for short-shifts to keep the shifting out of the boost power, and adjusting the vacuum modulator to soften the shifts. The bowden-cable change would mess up my downshift, the modulator adjustment could cause flaring at higher throttle settings, plus it was currently adjusted correctly so these seemed more like "band-aids".

So finally, I decided to adjust the ALDA just to see if I can recover some part-throttle acceleration and reduce the 2000rpm afterburner effect, not knowing it would solve two problems at once.

Not enough room to swing wrenches on mine (602 turbo / 201 body). Using a couple of large-sharp screwdrivers I was able to pick away at the cover until it came off. Loosening the 10mm lock-nut was easy, ... but then what a *****. Fortunately after about 1/4 turn, I was able to turn the adjustment out the rest of the 1turn with my fingertips, ... without too much pain. Tightened the locknut and away I went.

No smoke, but the part-throttle acceleration is more like a healthy gasser now. Very little change as the boost comes on, a smoother transition. I could possibly go further with the ALDA for max. take-off power, but it drives perfect as-is so I'm leaving it alone.

The lesson that I believe I learned is that the transmission in these cars has no torque-sensing to adjust shifting behavior, it relies on the vacuum modulator being matched to the power curve of the engine. In the case of lean/weak off-boost performance, the pedal position (and therefore the vacuum modulator position) is telling the transmission that there is substantial power and to shift accordingly, where my foot was further down than it should be and the power was less than it should be.

So in conclusion, for those awake enough to endure this rambling, an ALDA adjust might be just the thing to help soften those 1-2 shifts, and bring the engine back into spec. / original operating parameters. Might even save that 2nd-gear band from an early grave.

So much for keeping the story short.

- Jeff
190DT and projects

.......exactly.

Umm sorry guys, but whats an ALDA?

Use the search function you should be up for the rest of the night. Good debate about removing or not removing the ALDA.

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1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

“Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss

Yes, please search. Many, many, many pages of information about it.

Alda in short, is on top of the injection pump, and is responsible mostly for the increase in fuel necessary for turbo boost. With it not adjusted properly, you will have less off-boost power, so the initial moments of acceleration can be very weak with the alda not allowing enough fuel flow.

It has been covered several times, much information on how to adjust it is available.

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Gone to the dark side

- Jeff

Well looks like that is another thing I need to look into........

I have a 201 with the om602 turbo as well and I can testify that it was a pita to loosen up that alda screw. Actually it was impossible. I ended up removing the alda, which is a pita by itself. No place to mess around with big wrenches, but finally I made it.

I have a 5sp manual , advantage of living in europe , so I have no problems with shifting. To tell the truth I didn't really noticed too much of an improvement, if any, on my car. It only smokes a lot when launching with full throttle. I've read that in first gear the turbo does not kick in to prevent the drive shaft from snapping, so first gear is all smoke and massive acceleration up to 40kph (around 4600rpm). In 2nd gear I'm already in "boost" region which comes at around 2600rpm, so no smoke there.

With the alda in my hands I tried rotating the screw with a small screwdriver until I broke the screwdriver . Obviously it wasn't going to give me an easy time. I poured just a bit of engine oil on it, let it settle for a couple of minutes and that did the trick. The screw was rotating freely and effortlessly with the fingers.

One question though. Do I have to rotate the screw cw or ccw? Because it was maxed out cw and all I could to was rotate it ccw (the screw was screwing inwards alda). Reinstalled alda, tried out, still no extra power, just smoke. I guess my pump is still in good condition and it doesn't need the "fix". When I say no extra power, it doesn't mean I don't have power to boot. An year or so ago I measured my 0-100kph (0-62.5mph) times and the average came at around 12.5 s, with 2 people inside (me and a buddy holding the stop watch), with 205/60 r15 tires, a lot of crap in the trunk and suffering for grip in first and second gear. 60-100kph in 3rd comes in 6.5 seconds.

In a few words, if the screw on the alda is difficult to rotate, drop some engine oil on it. Let it settle for a couple of minutes and I'm sure it will be very easy to rotate.

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1992 Mercedes 190D 2.5 turbo 5sp manual. EGT+boost gauges. Boost controller set to ~14.5 psi. 1 1/4 turns on full load adjustment. LPG injection. Next in the list is water injection.

i have been having the same issues as you described. slow until 2k rpm, then it takes off. But this is only when i have the vacuum line to the tranny disconnected....

if i connected it, then it flares really bad. every gear it feels like it drops to neutral, and the engine takes off.

I check the vacuum system and it is in good shape, holds vacuum well.

It is still slow when connected, but as soon as i get to the gear shift it flares. what should i check?

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Grey '91 350SDL 214k Dad's car
Beige '81 240D 4 Speed 254k SOLD
Blue '82 300D 225k SOLD
White '95 E300D 46k SOLD
Blue '87 190D 2.5 Turbo 315k SOLD
Brown '80 240D 4 Speed 716k SOLD
Beige '80 300D N/A 119k SOLD
Blue '85 300D Model 186k T-Boned

It sounds like you have full vacuum all the time. Make sure all the lines are routed to/from the vacuum control device on the top rear of the injection pump. If the lever is disconnected or the vent hose connected to vacuum/blocked, it will not adjust the vacuum pressure to the throttle setting.

well, i drove it with my mitty vac connected and had like 17" at idle, and when i gave it throttle, i would drop down to near zero. then pop back up once cruising. it seemed normal to me. i guess i have to do it again, and video it. At least right down the numbers.

also i am looking into the K1 & K2 spring upgrade kits, hope those would help the flaring. not sure though why it would have such low power until 2k rpm. i checked the throttle stop against the IP and it is about 1/8 inch away. so that could use some adjustment.

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Grey '91 350SDL 214k Dad's car
Beige '81 240D 4 Speed 254k SOLD
Blue '82 300D 225k SOLD
White '95 E300D 46k SOLD
Blue '87 190D 2.5 Turbo 315k SOLD
Brown '80 240D 4 Speed 716k SOLD
Beige '80 300D N/A 119k SOLD
Blue '85 300D Model 186k T-Boned

the shut-off valve on my '87TD went bad day before yesterday so it had to be replaced, which means removing the ALDA unit. thanks to several posts here it was an easy job both to remove the ALDA and then re/re the shut-off valve.

since i had the ALDA out on the bench, i turned the adjusting screw 1 1/4 turns CCW. i have never touched this adjustment before and the tamper seal was still there so it was at the as-built setting. the car has always driven great, at least i thought so.

once everything was back together, the difference in performance and shifting was a big surprise. i was prepared for a little more low rpm acceleration, which was there. i did not realize the ALDA adjustment was going to change how the transmission shifted, which it did and much to the better. shifts are smoother especially between 1 and 2.

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punkinfair