Thanks to the groundwork laid down by Forced Induction, I decided to remove the ALDA from the '86 SDL. It's always been a dog off idle and it was time for some adjustments. Turns out that the ALDA is virgin. Never been tampered with.

So, with Lance's info, I plugged the pressure line from the overboost solenoid and took it for a spin.

Lo and behold, the vehicle is transformed. Just 1/4 pedal will move it out relatively smartly and 1/2 pedal will outperform the city traffic.

But, the most important issue is the smoke.

There was no smoke at any operating point provided the rack was not more than 2/3 open.

I was able to get a bit of smoke if I mashed the pedal below 2500 rpm. But, if you drive the vehicle with any sense of reserve, you'll never get it to smoke.

Now, the best part of the story:

Two 0-60 runs on the same roadway........in opposite directions.......using the G-Tech Pro:

9.79 seconds

10.32 seconds

This vehicle is faster than hell without that ALDA installed.

So, all you 603 fans, my strong advice is to simply get rid of the ALDA and all the associated plumbing. You clearly don't need it.

And, my thanks to Lance for the groundwork that generated this thread. The general consensus for the need of an ALDA to control excess fuel is clearly far too conservative.

Brian,
Did you acutally remove it, or simply disable everything going to it? I am still tyring to get a little more performace out of mine and would like to know exactly how to go about this.

__________________
Mike

'80 300D
'84 300D
'85 300D
'87 300D

Yep........gone.......it's sitting on a shelf in the garage.

You need a 25mm wrench and a set of channel locks. The wrench goes on the large nut and the channel locks hold the ALDA on the smaller nut directly below the ALDA.

Turn the ALDA counterclockwise and the big nut clockwise to break the lock between the two. Unthread the big nut and remove the ALDA. Plug the pressure line and you're done.

That W124 will be the proverbial rocketship when you get the ALDA removed. You won't believe it.

I'm NOWHERE near those low 0-60 times. Good ol' 617. 13.3 is my best so far.

Marshall Booth was so convinced that it's some magical device that keeps a precise A/F ratio. Now, including me, this is 3 that have reported great results from removing the ALDA.

I'll say it again, the ALDA is only an emissions device to prevent the output of black smoke under low boost conditions and adjust for high altitude operation. Anyone that watches how they drive can do very well without one. If they are the type that just puts the foot down to go every time, they might wanna keep the alda.

What exactly is the ALDA? I'd like to find some more info about adjusting it...

Well, the 603 definitely packs a better punch than the 617. The SD makes the run in 12.70 seconds.

Marshall is definitely mistaken on this one. The ALDA is definitely not required if you drive the vehicle with just a touch of intelligence.

Exactly. Thanks, again!!

I don't know Brian, maybe there's a difference between IPs. With the new IP on my 617, I have to keep it turned at least half way down or I get LOTS of smoke, even at 1/4 throttle. I assume that removing it is "richer" than turning it all the way up? If so, there's no way I could remove mine. Is it possible that older IPs are worn enough that they are beyond the range of the ALDA adjustment?

I might have to pull mine off tomorrow and give it a shot.

__________________
Mike

'80 300D
'84 300D
'85 300D
'87 300D

Could definitely be the case that a 20 year old IP is providing less fuel than a brand new one. Accordingly, you'll definitely need an ALDA and the older engine can easily be run without one.

Removing it gives no control over the rack other than your right foot. You get maximum fuel when you mash the pedal, whether the engine can use the fuel, or not.

This is all REALLY interesting - would this work on my '91 350SD?!?!?

I'm removing the EGR and plugging the ARV this week - perhaps the ALDA is next in line......

Whether it will work without smoke is the question. You'll need to try it and report back.

How about this combination:

No EGR, plugged ARV, no ALDA + 100% heated WVO (GreaseCar)

There's already so little smoke with WVO, maybe it would work...

I'll see if I can work it out when I am having the other stuff done.

By the way - a couple questions...

What does ALDA stand for?
Where is it and what does it look like???

I suspect so, my new IP is much more sensitive to small ALDA adjustments than the old one. I've been back and forth a half dozen times to find the "sweet spot" of good power without too much smoke.

This is interesting enough to try on my 617. I probably will wait until I have a boost gauge installed so I can see what the numbers are with and without ALDA. Thanks, Brian!

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

So how do you test this? Just plug the vac line off the ALDA and take it for a spin?


I would probably install and egt guage before getting rid of mine. Running it to 5k rpm in a few gears may produce some pretty high temps from all that fuel.


Now Brian add a bit more boost and see if you can get it consistantly below 10 seconds.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200