My (long-winded) experience with the ALDA on om617a
My (long-winded) experience with the ALDA on om617a
I know for some reason the function and value of the ALDA is a heated topic on most of the MB forums. For the sake of people searching, I thought I would explain what my experience with the ALDA on my om617.952 engine was. Just as a baseline, here is where the car sits as of now.
Condition of engine: My engine starts right up, idle is steady, no smoke at idle, medium blow by, compression in the 350 range. New fuel filters, injectors, IP timing set, EGR delete, valves adjusted, new glow plugs etc etc. I would say the engine is a solid B+ condition. I have small vacuum leak that I haven't addressed yet, but everything is working, and the vacuum pump output was tested and in spec. No boost gauge so I don't know the condition of the turbo, but it looks and sounds good.
Transmission: I have not yet adjusted the modulator, but I have adjusted the bowden cable. Drives reasonably well. B- perhaps, but fix the engine shutoff switch vacuum leak and adjust better and I'm sure it will operate properly, it feels pretty healthy.
With that out of the way, I have heard the ALDA is about boost control, fuel control, drivability, emissions control, altitude compensation and possibly even gives a good reach-around. I've heard people comment, "Don't touch it, do you think you're as smart as a Mercedes engineer?", "Back the screw out a few turns CCW till you see smoke", and others just say "Just take the damn thing out"
My understanding based on the FSM, and just looking at the thing, I think it's pretty clear what this thing was for. It is a fairly crude mechanical/analog fuel controller meant to provide emissions control, over boost protection, and altitude compensation. A modern computer controlled car can manage things a lot better than the ALDA can. Frankly, I think an enthusiast with a good butt dyno, or a boost gauge, boost controller, and EGT gauge can manage better than the ALDA was ever going to. I took it apart (Pics tomorrow, sorry!) and the mechanism is a joke in there, not to mention what 25 years of running had done to it. Maybe somebody out there has one that is still operating in spec, but I suspect just like the EGR valve, most everyone's is next to useless by now anyway. The only control it has over your engine is just to limit fuel output, plain and simple. The shaft it connects to that goes into the IP cuts the fuel out when it is pressed down and a spring returns it back up restoring normal running. It does not "Add fuel" when the boost arrives, it simply holds back the fuel you asked for with the gas pedal until the boost gets there, then lets you have it back. Pushing the shaft down with my finger, the idle drops pretty low, in fact, pulling the linkage to have the engine running at WOT the engine probably didn't go above 2k rpm until I let go of the ALDA shaft at which point it revved as normal. I didn't realize it had that level of control, but when it wants to cut fuel, it can cut it quite a bit.
Impression of it's effect on drivability: My ALDA had already been tinkered with, but without touching it from there, the car drove pretty inconsistently. Sometimes it would struggle get up my driveway, other times it would really get off the line pretty well. No black smoke ever. Even when the car was behaving itself, it drove pretty much just like a 300D I had a few years ago. It feels like you have to push the throttle down quite a ways, wait for the boost rush, and then bring your foot off the gas to try to get consistent acceleration while also trying to manage when the auto transmission was going to shift. So driving it has quite a different 'feel' to it when compared to a 'normal' car. I then loosened the lock nut, cranked the adjusting nut all the way CCW to stop, locked it down, and tried driving it again for a few days. No change.
Needless to say, one afternoon after it felt like I was towing a boat anchor around town, I took it off and capped the boost line running to it to see if it was causing my problem. Wow, what a difference. Not only did it fix the inconsistent throttle response, but it drives much more 'normally'. I don't have to push the throttle down, wait for the rush, back off, hope it doesn't shift and adjust from there. I press 1/2 way down, and I get about 1/2 the power it's going to give me. No drama. For my efforts I'm rewarded with a small puff of black smoke when I stomp it down, but otherwise no smoke at idle or when normally driving. It feels more powerful, more often, and frankly is easier to drive.
Conclusion: If you want my advice, just rip it off. Enjoy the gas pedal actually controlling the IP directly instead of having the ALDA decide when and how much fuel to let you have. Vice-grips on the big nut on the bottom, a quick tap on the top with a mallet and a cold chisel to loosen it (Or a 24mm wrench on the small flange cast into the ALDA itself on the underside, but I found it pretty well seized up) and just unscrew it. Make sure to cap off the boost line at the intake manifold and you can remove the switchover valve if you want, it won't do anything now. I didn't damage it doing this, but after 30 seconds behind the wheel it was clear it's never going back on. People say it has a seal so no need to address the shaft sticking out, but I'm going to be off roading with my G wagen, so I'm going to seal it shut.
This post is IMHO, YMMV, just my 2¢ and all that.
Sorry in advance, this post got crazy long. If anyone out there reading this is anything like me, I hope at least one person appreciates that I tried to demystify something that isn't that complicated so they can make a more informed decision for themselves based on common sense and actual experience as opposed to hypothetical conjuring and hearsay.
I know for some reason the function and value of the ALDA is a heated topic on most of the MB forums. For the sake of people searching, I thought I would explain what my experience with the ALDA on my om617.952 engine was. Just as a baseline, here is where the car sits as of now.
Condition of engine: My engine starts right up, idle is steady, no smoke at idle, medium blow by, compression in the 350 range. New fuel filters, injectors, IP timing set, EGR delete, valves adjusted, new glow plugs etc etc. I would say the engine is a solid B+ condition. I have small vacuum leak that I haven't addressed yet, but everything is working, and the vacuum pump output was tested and in spec. No boost gauge so I don't know the condition of the turbo, but it looks and sounds good.
Transmission: I have not yet adjusted the modulator, but I have adjusted the bowden cable. Drives reasonably well. B- perhaps, but fix the engine shutoff switch vacuum leak and adjust better and I'm sure it will operate properly, it feels pretty healthy.
With that out of the way, I have heard the ALDA is about boost control, fuel control, drivability, emissions control, altitude compensation and possibly even gives a good reach-around. I've heard people comment, "Don't touch it, do you think you're as smart as a Mercedes engineer?", "Back the screw out a few turns CCW till you see smoke", and others just say "Just take the damn thing out"
My understanding based on the FSM, and just looking at the thing, I think it's pretty clear what this thing was for. It is a fairly crude mechanical/analog fuel controller meant to provide emissions control, over boost protection, and altitude compensation. A modern computer controlled car can manage things a lot better than the ALDA can. Frankly, I think an enthusiast with a good butt dyno, or a boost gauge, boost controller, and EGT gauge can manage better than the ALDA was ever going to. I took it apart (Pics tomorrow, sorry!) and the mechanism is a joke in there, not to mention what 25 years of running had done to it. Maybe somebody out there has one that is still operating in spec, but I suspect just like the EGR valve, most everyone's is next to useless by now anyway. The only control it has over your engine is just to limit fuel output, plain and simple. The shaft it connects to that goes into the IP cuts the fuel out when it is pressed down and a spring returns it back up restoring normal running. It does not "Add fuel" when the boost arrives, it simply holds back the fuel you asked for with the gas pedal until the boost gets there, then lets you have it back. Pushing the shaft down with my finger, the idle drops pretty low, in fact, pulling the linkage to have the engine running at WOT the engine probably didn't go above 2k rpm until I let go of the ALDA shaft at which point it revved as normal. I didn't realize it had that level of control, but when it wants to cut fuel, it can cut it quite a bit.
Impression of it's effect on drivability: My ALDA had already been tinkered with, but without touching it from there, the car drove pretty inconsistently. Sometimes it would struggle get up my driveway, other times it would really get off the line pretty well. No black smoke ever. Even when the car was behaving itself, it drove pretty much just like a 300D I had a few years ago. It feels like you have to push the throttle down quite a ways, wait for the boost rush, and then bring your foot off the gas to try to get consistent acceleration while also trying to manage when the auto transmission was going to shift. So driving it has quite a different 'feel' to it when compared to a 'normal' car. I then loosened the lock nut, cranked the adjusting nut all the way CCW to stop, locked it down, and tried driving it again for a few days. No change.
Needless to say, one afternoon after it felt like I was towing a boat anchor around town, I took it off and capped the boost line running to it to see if it was causing my problem. Wow, what a difference. Not only did it fix the inconsistent throttle response, but it drives much more 'normally'. I don't have to push the throttle down, wait for the rush, back off, hope it doesn't shift and adjust from there. I press 1/2 way down, and I get about 1/2 the power it's going to give me. No drama. For my efforts I'm rewarded with a small puff of black smoke when I stomp it down, but otherwise no smoke at idle or when normally driving. It feels more powerful, more often, and frankly is easier to drive.
Conclusion: If you want my advice, just rip it off. Enjoy the gas pedal actually controlling the IP directly instead of having the ALDA decide when and how much fuel to let you have. Vice-grips on the big nut on the bottom, a quick tap on the top with a mallet and a cold chisel to loosen it (Or a 24mm wrench on the small flange cast into the ALDA itself on the underside, but I found it pretty well seized up) and just unscrew it. Make sure to cap off the boost line at the intake manifold and you can remove the switchover valve if you want, it won't do anything now. I didn't damage it doing this, but after 30 seconds behind the wheel it was clear it's never going back on. People say it has a seal so no need to address the shaft sticking out, but I'm going to be off roading with my G wagen, so I'm going to seal it shut.
This post is IMHO, YMMV, just my 2¢ and all that.
(07-05-2012, 06:51 AM)bryant.cw Conclusion: If you want my advice, just rip it off. Enjoy the gas pedal actually controlling the IP directly instead of having the ALDA decide when and how much fuel to let you have.
Yup! If you're paranoid about overboosting, use the manifold switch to run a dummy light.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
07-05-2012, 08:25 AM #3(07-05-2012, 06:51 AM)bryant.cw Conclusion: If you want my advice, just rip it off. Enjoy the gas pedal actually controlling the IP directly instead of having the ALDA decide when and how much fuel to let you have.
Yup! If you're paranoid about overboosting, use the manifold switch to run a dummy light.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
I think most people running this engine don't have unlimited funds, so I thought I should share my experience.
To be clear I don't feel the ALDA is useless, merely a fairly crude type of fuel control, that at this age, is probably is not working well enough to justify keeping it. I think how much smoke you get will be a function of tightness of engine/amount of blow by, clean valve seats, valve adjustment, condition of injectors, fuel quality, IP timing, and condition of IP. Without a full rebuild of everything, most people will probably get different results, but a good tune up and removing the ALDA will probably yield positive results.
I think most people running this engine don't have unlimited funds, so I thought I should share my experience.
(07-06-2012, 03:40 AM)bryant.cw ....a good tune up and removing the ALDA will probably yield positive results.
I think most people running this engine don't have unlimited funds, so I thought I should share my experience.
That's a great way to sum it up. If you had a brand new engine & ALDA, you would probably outperform an old one with no ALDA.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
07-06-2012, 08:43 AM #6(07-06-2012, 03:40 AM)bryant.cw ....a good tune up and removing the ALDA will probably yield positive results.
I think most people running this engine don't have unlimited funds, so I thought I should share my experience.
That's a great way to sum it up. If you had a brand new engine & ALDA, you would probably outperform an old one with no ALDA.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
Captain America
07-10-2012, 02:50 AM #7I just like the fact that I can now brake boost and do a burnout
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
im wondering , if i remove the alda , do i need to worry about any springs popping ofrf inside the pump?
on thread relative , some body mentioned losing a spring ? and in this thread it say just pop it off and block the hole ?
any body have pics of a removal ?
ok , sorry to double post. i couldnt get my alda off
diddnt have the right size wrenches and when i did get it to turn ccw with a little love and some vice grips , the corner of the unit was hitting the trans switch valve . so i did the unmentionable.... i adjusted the screw on top :0 . but with that said , im the first . i backed it all the way ccw after removing the lock nut , gently till it stopped . it was about 5 full turns . a noticeable difference was had . i could fell it in the but dyno 
backing out of my drive broke the tires , on dirt< but it wouldn't do that before . pick up was better and the transition into boost was smother and a little quicker . but putting down the road going 40-50, in 4th gear . there was actually good acceleration till boost . no overall differences after that , but it def feels better .
awesome write up , i was messing with my car this morning . i disconected the boost line to the alda and at idle tried adding pressure to see if i got any drop in or raise in idle nothing . applied pressure and vacume nothing . ran up and down the street , with the lines jumped , no switch. and not much diff in drive, plugged both lines , and ran it , it would stay in 2nd gear longer , no real diff in boost, maybe less. so im going to remove it and let you know .
im wondering , if i remove the alda , do i need to worry about any springs popping ofrf inside the pump?
on thread relative , some body mentioned losing a spring ? and in this thread it say just pop it off and block the hole ?
any body have pics of a removal ?
ok , sorry to double post. i couldnt get my alda off
diddnt have the right size wrenches and when i did get it to turn ccw with a little love and some vice grips , the corner of the unit was hitting the trans switch valve . so i did the unmentionable.... i adjusted the screw on top :0 . but with that said , im the first . i backed it all the way ccw after removing the lock nut , gently till it stopped . it was about 5 full turns . a noticeable difference was had . i could fell it in the but dyno backing out of my drive broke the tires , on dirt< but it wouldn't do that before . pick up was better and the transition into boost was smother and a little quicker . but putting down the road going 40-50, in 4th gear . there was actually good acceleration till boost . no overall differences after that , but it def feels better .
1984 Mercedes-Benz 300TD Turbo - 260k miles - Daily driver
1982 Yamaha XV920RJ - 9k miles - Currently in pieces
I have valve wrenches and timing tools for rent! PM for details!
Secondaries
10-05-2012, 05:27 PM #9Quick question. Does the ALDA do anything with the adjustment screw backed all the way out? To ask another way: is there a difference performance wise between full CCW adjustment and ALDA removal?
1984 Mercedes-Benz 300TD Turbo - 260k miles - Daily driver
1982 Yamaha XV920RJ - 9k miles - Currently in pieces
I have valve wrenches and timing tools for rent! PM for details!
(10-05-2012, 05:27 PM)Secondaries Quick question. Does the ALDA do anything with the adjustment screw backed all the way out? To ask another way: is there a difference performance wise between full CCW adjustment and ALDA removal?
yes there is..if ALDA is not functioning properly
removal will take care of that....
.
(07-05-2012, 08:25 AM)Simpler=Better Yup! If you're paranoid about overboosting, use the manifold switch to run a dummy light.
one paranoid over here
details details please 
.
500SEC euro gen II powered by OM617a stolen from 84 300SD .... with 280se transmission now
----------------------------------------------------------
.
(10-05-2012, 05:27 PM)Secondaries Quick question. Does the ALDA do anything with the adjustment screw backed all the way out? To ask another way: is there a difference performance wise between full CCW adjustment and ALDA removal?
yes there is..if ALDA is not functioning properly
removal will take care of that....
.
(07-05-2012, 08:25 AM)Simpler=Better Yup! If you're paranoid about overboosting, use the manifold switch to run a dummy light.
one paranoid over here
details details please .
500SEC euro gen II powered by OM617a stolen from 84 300SD .... with 280se transmission now
----------------------------------------------------------
.
(10-08-2012, 07:06 AM)cho(07-05-2012, 08:25 AM)Simpler=Better Yup! If you're paranoid about overboosting, use the manifold switch to run a dummy light.one paranoid over here
.
The overboost switch grounds out to the manifold at something like 1.5 bar (I think). When it does that , it triggers the overboost solenoid which restricts fuel to the ALDA. All you would need to do is piggyback a light from the overboost switch. Wire the warning light's ground to the overboost's output, and the warning light's hot to a fused ignition circuit. If you see 1.5bar or more the light should turn on.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
10-08-2012, 09:05 AM #11(10-08-2012, 07:06 AM)cho(07-05-2012, 08:25 AM)Simpler=Better Yup! If you're paranoid about overboosting, use the manifold switch to run a dummy light.one paranoid over here
.
The overboost switch grounds out to the manifold at something like 1.5 bar (I think). When it does that , it triggers the overboost solenoid which restricts fuel to the ALDA. All you would need to do is piggyback a light from the overboost switch. Wire the warning light's ground to the overboost's output, and the warning light's hot to a fused ignition circuit. If you see 1.5bar or more the light should turn on.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
(10-08-2012, 09:05 AM)Simpler=Better(10-08-2012, 07:06 AM)cho(07-05-2012, 08:25 AM)Simpler=Better Yup! If you're paranoid about overboosting, use the manifold switch to run a dummy light.one paranoid over here
.
The overboost switch grounds out to the manifold at something like 1.5 bar (I think). When it does that , it triggers the overboost solenoid which restricts fuel to the ALDA. All you would need to do is piggyback a light from the overboost switch. Wire the warning light's ground to the overboost's output, and the warning light's hot to a fused ignition circuit. If you see 1.5bar or more the light should turn on.
thanks mate,
I dont have OB solenoid (or wires that comes with) ,only OB switch is present...but you gave me idea I can work with
.
500SEC euro gen II powered by OM617a stolen from 84 300SD .... with 280se transmission now
----------------------------------------------------------
.
(10-08-2012, 09:05 AM)Simpler=Better(10-08-2012, 07:06 AM)cho(07-05-2012, 08:25 AM)Simpler=Better Yup! If you're paranoid about overboosting, use the manifold switch to run a dummy light.one paranoid over here
.
The overboost switch grounds out to the manifold at something like 1.5 bar (I think). When it does that , it triggers the overboost solenoid which restricts fuel to the ALDA. All you would need to do is piggyback a light from the overboost switch. Wire the warning light's ground to the overboost's output, and the warning light's hot to a fused ignition circuit. If you see 1.5bar or more the light should turn on.
thanks mate,
I dont have OB solenoid (or wires that comes with) ,only OB switch is present...but you gave me idea I can work with
.
500SEC euro gen II powered by OM617a stolen from 84 300SD .... with 280se transmission now
----------------------------------------------------------
.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
10-09-2012, 07:38 AM #13I scrapped mine ( A boost gauge took it's place) but that setup really is a good foolproofer for people who don't watch their gauges
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
1 Guest(s)
1 Guest(s)