Exactly the question that came to my mind and was the first question I asked the MB engineers, their contention was that since the boost is quite mild, compensation can be achieved by metering the IP precisely and therefore ALDA was not deemed to be necessary, the later Euro-II-IV versions also get an intercooler along with the ALDA so I guess the IP metering method became impossible for them.

Good information for new members.

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Simply turning this screw 3/4 to 1-1/4 turns is not the correct method of adjustment.

The correct way to adjust this device is to slowly back the screw out (CCW) until an increase in idle speed is detected.

As you meter more fuel into the engine, the idle speed will increase, but so will the noise of combustion.

The correct setting is when idle speed is increased slightly and the sound of the combustion process is as quiet as possible.

Camshaft and Injektor Pump Timing should be properly adjusted befoe making this adjustment.

Injektor Delivery Pressure should also be set to specification before making these changes.

I should also add that I generally set the wastegate to deliver about 12 to 14 psi of boost pressure on my personal engines, which also has a great affect on power output.

I hope this information is helpful...Bert

A couple of minor corrections:

1) Correct ALDA adjustment is not related to idle speed (although it *could* affect the idle). Turn it CCW until there is no more power gain off idle. If you're not sure, turn it back CW until you notice a power *loss*, then go CCW 1/8 turn or so. This should be about perfect. A slight puff of smoke leaving a stop is normal. Don't look for smoke at WOT, you'll probably never see any even with the ALDA 'maxed' out, since that is limited by the internal full load setting. Also ignore smoke in other car's headlights, that's normal too, look for smoke on bright sunny days.

2) If you boost pressure is below about 10psi, you may get a power gain (possibly a big gain) by turning it up to spec. The spec for OM617 engines is 0.75-0.85 bar (11-12psi), spec for 86-87 OM602/603 engines is 0.85-0.95 bar (12-14psi), and spec for 1990-up OM602/603 engines went back to 0.75-0.85 bar. If your car is making normal power at 10psi, you WILL NOT get more power by simply turning up the boost. I proved this on both my 617 and my 603. Turning up the boost will only increase intake air temps, exhaust backpressure, and EGT's. More power requires more fuel, which requires an intercooler, which requires a whole separate discussion. If your boost is below spec, definitely turn it up to spec! Measure boost a WOT in 3rd gear at 4000rpm. Measure boost at the ALDA... if it's very low or near zero, make sure all the tubing is clean between the manifold and the ALDA - this is often plugged with soot.

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In every instance, I have noticed an increase in idle speed. Even when the increase is slight, I have been able to measure it.

I might just experiment with your method on the next 617 I build...Bert

I thought the turbo injection pump was equipped with an idle governor. If that's the case, by adjusting the ALDA to the point where it affects the idle is defeating or limiting the governor?

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I just adjusted my ALDA too and found it was maxed out, probably by the previous owner. This may explain why I seemed to have a lot of smoke pulling away from a stop. So I turned it in a full turn in 1/4-turn increments until power dropped, then screwed it back out a 1/4 turn. So now it seems like I've got the same power I had before -- hopefully with less smoke and more mpg! Very simple procedure, though my neighbors probably wondered why I was driving around smoking up the 'hood!

Now to check my boost levels. I've got a boost gauge on the shelf I'm about to install for that.

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I've been reading about ALDA adjustment for the past few weeks now, and finally found time to do it, and I must say! What a difference it has made. I did it in my '83 300D w/ 240K miles, and also on my '85 300D w/ 193K miles, and the improvment is remarkable. The '83 always seemed quicker off the line of the two, being able to keep up with traffic with 1/2 to 3/4 throttle, but now I can keep up with 1/4 to 1/2 throttle. Can't wait to see if my fuel milage has improved. I'm very pleased, thanks to everyone for posting about ALDA adjustments on this website, it made it very easy to have the laptop right next to me while browsing this forum.


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'83 300D - 240K
'85 300D - 193K
'90 PowerRam 250 - 5.9L CTD - 200K
'01 Intrepid R/T - 40K

I adjusted the ALDA as instructed in the thread and noticed an immediate improvement in the idle-20 mph range of my '84 300 TDT. It ran like a cement mixer before the turbo kicked in; now it's smooth through the entire power range. Thanks for the advice.

It certainly makes a difference. I've tweaked my 82 300D back and forth a couple of times to try to find maximum low rpm power with an acceptable amount of smoke. It's easy to back it out too far and get more smoke with little or no additional power gain. I think I have it about where I want it now.

well i am new to cars and i have found my alda but i dont know where everyone is adjusting it. i have a black round plastic piece on the top of my alda, but that is it. where is the screw that i am supposed to turn CCW?

thanks

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Its under that black cap.
You have to take the plastic part off and remove the metal ring deal (generally speaking...rip it off).

Don't expect to put the cover back on. This is the crude way off course and makes the adjustment easy. There is probably a right way

I just used the good o'l dremel.... cap...didn't survive.

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Wow, I've never even seen one of those caps still intact, mine sure wasn't.

How far do you turn it CCW?

I'm at 5000' elevation and need every ounce of pep I gan get on a 240..

My alda has a little drop of yellow glue to show it has not been touch.. would that be from the factory ona 81? My car spent 98 of it's life at sea level till this past spring.

found a interesting article for you turbo guys..
http://www.serenitysys.com/MB/Service_Info/Turbo_Tweak/tweaking_the_mercedes_617_turbo_.htm