ALDA removal........OM603 - PeachParts Mercedes-Benz Forum

Brian Carlton · #1 08-26-2006, 05:48 PM

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.

sublettm · #2 08-26-2006, 05:58 PM

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.

Brian Carlton · #3 08-26-2006, 06:13 PM

Quote:

Originally Posted by sublettm

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.

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.

Cr from Texas · #4 02-24-2008, 01:55 AM

Quote:

Originally Posted by Brian Carlton

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.

Brian,
What did you plug the pressure line with (is it very high pressure)? Didn't this leave some type of fitting where it was removed that had to be filled with something? What.

Another thread is looking for a summary of all that can be removed:

http://www.peachparts.com/shopforum/showthread.php?t=214456

Maybe you'll join that thread also - please.

Charles

Cr from Texas · #5 02-24-2008, 02:02 AM

Sorry for the above post. Most of what I asked was on the next pages of the thread. Being a newbie, I saw the submit square (actually one at the bottom of every page) and thought I was at the end of the thread. I'll try to be more careful.

Charles

Cr from Texas · #6 02-24-2008, 05:18 AM

OK, I've now read the entire thread and I appreciate how often the regulars are writing the same responses. The only confusing part was trying to keep straight if the comments applied to all models, 123, 617, etc. Now I'll commit to some wrench and mightly vac time and see if I can't fix several related problems.
Thanks,
Charles

#7 08-26-2006, 06:18 PM

Quote:

Originally Posted by Brian Carlton

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.

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.

300SD81 · #8 08-26-2006, 06:37 PM

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

Brian Carlton · #9 08-26-2006, 06:48 PM

Quote:

Originally Posted by ForcedInduction

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.

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!!

#10 08-26-2006, 07:05 PM

Quote:

Originally Posted by Brian Carlton

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?

sublettm · #11 08-26-2006, 07:13 PM

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

Brian Carlton · #12 08-26-2006, 07:21 PM

Quote:

Originally Posted by Craig

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?

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.

Blevinsax · #13 08-26-2006, 07:29 PM

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......

#14 08-26-2006, 07:47 PM

Quote:

Originally Posted by Brian Carlton

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.

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.

Ian White · #15 10-21-2009, 04:34 PM

Quote:

Originally Posted by Brian Carlton

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.

I removed my ALDA then put it back on because I didnt know what to do with the gaping hole it left in the top of the IP without it there. Also what do I do with the rod the is sticking up, I believe this is the rack limiter rod, what should I do?