WOW! ALDA adjustment makes night and day difference - Page 2 - PeachParts Mercedes-Benz Forum

wolf_walker · #16 06-20-2004, 01:13 AM

Has it occured to anyone else that perhaps were compensating for something else being worn or out of spec by adjusting the ALDA? I know on my 300D, it just could not have been that much of a dog off the line when new, not for that kinda money..
Makes one wonder..

SoyDriver Matt · #17 06-20-2004, 12:03 PM

Well, I've heard that the alda gradually leans out the mixture over the years due to the spring slowly getting less "springy". And on mine (just did it to my nice SD after testing on the beater) they would both go well once the turbo was boosting,and I did adjust the valves, checked the timing, cleaned the banjo bolt on the boost line, disconnected the boost line to see if the turbo was boosting, changed the fuel filters, cleaned the tank filter, and none of it made a noticable difference, but adjusting the alda, WOW, immediate change in the off-the-line performance. Now I'm not scared to pull out into traffic anymore!

wolf_walker · #18 06-20-2004, 12:09 PM

Quote:

Originally posted by SoyDriver Matt
Well, I've heard that the alda gradually leans out the mixture over the years due to the spring slowly getting less "springy". And on mine (just did it to my nice SD after testing on the beater) they would both go well once the turbo was boosting,and I did adjust the valves, checked the timing, cleaned the banjo bolt on the boost line, disconnected the boost line to see if the turbo was boosting, changed the fuel filters, cleaned the tank filter, and none of it made a noticable difference, but adjusting the alda, WOW, immediate change in the off-the-line performance. Now I'm not scared to pull out into traffic anymore!

I know the feeling and I had the same experence. I just wonder.
I know I've driven one 85 SD with a pretty fresh engine, 100K miles or so, and with no alda adjustment it was darn spirited, even in an SD. Who knows..

gsxr · #19 06-21-2004, 02:16 PM

You can turn up the ALDA all you want without fear of engine meltdown - the IP has a separate, internal full-load fuel limit. That is the adjustment you need an EGT for. You will never need to buy a new IP from adjusting (or even breaking!) the ALDA. If you force the screw past it's limit, you will break the sealed aneroid capsule, and need a new (used) ALDA. They're commonly available from junkyards pretty cheap, but a new one from Bosch is something like $100-$200. You can test if the seal is leaking with a MityVac pressure pump, it should pump up to 15psi and hold that pressure. If it leaks down, or leaks as fast as you can pump, the shaft seal is toast and you are losing part-throttle power. A new seal is ~$5-10 and takes an hour or so to replace. Photos here:

http://www.meimann.com/images/mercedes/OM603_injection/

BoostnBenz · #20 06-21-2004, 11:56 PM

you talked me into it.

My 84 was so peppy, whether the road was wet or dry it'd do a nice little burnout anytime you wanted to. The 83 has a different rearend in it but just feels so much slower. I wish I had a pressure gauge to check it with, don't care to spend the money on one at the moment and the one in my talon is a "permanent" install.

#21 11-26-2004, 04:35 AM

I just did my ALDA too and I have it maxed out with still no more visible smoke than I started out with but a CRAPLOAD more power..
If I snap the throttle I get pretty good smoke but under load its light...which is a good fuel/air ratio
Now I just wonder how worn out that spring inside and how much more could be offered by the screw if it were more springy?
Any ideas?
Dad is a diesel mechanic with plenty of IP tinkering years under his belt so don't hesistate with the scary ideas! hehe
Could the fuel screw inside the IP that people talk about (that SCARY ADJUSTMENT) be adjusted to compensate for this problem or would that be a nono?
My guess is that since I have light smoke at idle I have plenty of "no boost" fuel which means don't play with the IP...your problems are all in the ALDA and 'under boost" conditions
Seem good?
Anyone have a ALDA that is low miles? Anyone ever taken one apart?
Thanks!

Brandon

Breckman99 · #22 11-26-2004, 05:06 AM

Speaking of the internal adjustment....
Anybody try this one yet?

P.E.Haiges · #23 11-26-2004, 09:06 AM

Does adjusting the ALDA for more power decrease the fuel mileage?

P E H

WANT '71 280SEL · #24 11-26-2004, 09:20 AM

P.E. yes I've heard it does reduce mileage by a couple mpg's maybe? The ALDA on my car still has the cap, so I asssume it's never been done before. I might try it sometime, but I'm pretty satified as is since I average 18mpg 75% city.
Thanks
David

gsxr · #25 11-26-2004, 10:35 AM

When the ALDA is properly adjusted you lose zero MPG. If you adjust it too far (too rich), you will reduce MPG. Don't look for smoke at WOT - you may never see any! The ALDA is still limited by the internal full-load delivery screw. Adjust the ALDA richer until there is no more power gain *off idle*, then go back (leaner) a little bit - that should be about the perfect setting. If you're getting more than a slight puff of smoke leaving stop signs, it's probably too rich.

Adjusting the internal full-load screw increases delivery quantity across the whole RPM range. That means if you turn up the full-load setting, you probably will have to turn the ALDA leaner to compensate, as it will probably be too rich off-idle. It may also increase the idle speed, requiring adjustment to the idle stop setscrew on the throttle linkage.

Yes we have taken an ALDA apart. I did this to replace the shaft seal, which was leaking, and robbing part-throttle power. There's not much inside to look at. No need for a "low-miles" unit, if yours holds pressure it's fine, if not replace the shaft seal and it's as good as new. Photos are here.

About the internal adjustment - I'm about to try this myself, along with another diesel nut (Casey), on our OM603's. The danger is increasing EGT's too much. Casey got a pyrometer and plans to do some baseline testing in stock form before turning up the full-load setting, then turn it up and see what happens to EGT's with the extra power. That's Stage 1. Next up is water injection OR intercooling (Stage 2), and Stage 3 would be both IC and WI. (Stage 4 and beyond requires massive modifications which we're not interested in at the moment - although the Finns are at about Stage 11 by now...!) Full details on that, including a link to the Finns forum (the Diesel Gods who got 400+hp from OM603's), is here.

#26 11-26-2004, 04:46 PM

Quote:

Originally Posted by gsxr

Adjusting the internal full-load screw increases delivery quantity across the whole RPM range. That means if you turn up the full-load setting, you probably will have to turn the ALDA leaner to compensate, as it will probably be too rich off-idle. It may also increase the idle speed, requiring adjustment to the idle stop setscrew on the throttle linkage.

About the internal adjustment - I'm about to try this myself, along with another diesel nut (Casey), on our OM603's. The danger is increasing EGT's too much. Casey got a pyrometer and plans to do some baseline testing in stock form before turning up the full-load setting, then turn it up and see what happens to EGT's with the extra power.

Alright cool that perfectly answered my question.
Keep us updated on the full-load adjustments...I would be very curious and a apt experimenter to do this on my 617 as compared to your 603's...(differences for forum members)
Drop me a email sometime if you guys get going on that...very interested.

Brandon

DslBnz · #27 11-26-2004, 07:30 PM

An interesting perspective into this is that we can feasably get 400 + hp out of these machines and still have mechanical durabiity as well as reliability.

While MB keeps making more and more powerful diesel MB's, they are constantly trying to find ways to eliminate the excessive NOx emissions that a diesel puts out. Even suggesting the radical urea canisters as a future soot-trap, lol. Meanwhile, we, with our 30 year old diesel engines, can pump out power similar to E55 kompressor models if necessary to keep up with the traffic of tomorrow.

Let's not forget the fact that even though these cars would be putting out pretty good power, they will not have an over-abundance of check-engine-electronics triggering sensory.

#28 11-26-2004, 10:37 PM

Quote:

Originally Posted by DslBnz

Let's not forget the fact that even though these cars would be putting out pretty good power, they will not have an over-abundance of check-engine-electronics triggering sensory.

Well put...requires the drivers to know a bit more than "right pedal is go and left is stop"....
I am in tune with all the little noises, clanks, clunks, clatters, etc. that this machine makes (as are most of us!). Defintely not your 'run of the mill" drivers

Gurkha · #29 11-26-2004, 11:10 PM

While on the subject of ALDA here is my take, on my turbo Om 616 Euro-I spec engine, there is no ALDA but on later Euro-II to Euro-IV spec, the ALDA has been incorporated along with other electronic IP controls, having driven both versions, I find the Euro-I non ALDA engine to have a much better throttle response although at a cost of little knock at certain RPM, the ALDA version is quieter but the response isn't that good.

#30 11-27-2004, 03:34 AM

Quote:

Originally Posted by Gurkha

While on the subject of ALDA here is my take, on my turbo Om 616 Euro-I spec engine, there is no ALDA but on later Euro-II to Euro-IV spec, the ALDA has been incorporated along with other electronic IP controls, having driven both versions, I find the Euro-I non ALDA engine to have a much better throttle response although at a cost of little knock at certain RPM, the ALDA version is quieter but the response isn't that good.

How does that version adjust for enrichment while under boost?
*curious*