Is this what the ALDA is contributing to?

[Silber Adler]

As I am gently accelerating I get the boost up to 1psi then 2 and then as it goes to 3, it jumps up to 5 or 6.

I understand how the turbo works, is based on the exhaust output. More fuel and more rpm the the more boost.

I am not expecting a linear pressure to boost but once it at the 5-6 it is very linear to get it to the max of 9.

I know the ALDA is meant to cut fueling (hence boost too) until it gets to a certain point. Is the jump in boost, the point where the ALDA is letting off the restriction?

I have it turned out about 3/4 of a turn (The screw is at the outer limit as it won't turn out any more) which should remove some of the restriction.

At no time does my engine put out any smoke.

I believe that I have read most of the ALDA threads.

[vstech]

take it off, see if that makes any change.

[Diesel911]

You might try bypassing the Over Pressure Relay Switch that is between the Intake Manifold Boost Line and the ALDA.

While they all work together I would say the Boost Pressure has the lead and the ALDA responds to that and then more Fuel, more Exhaust Pressure and Volume.

It the Waste Gate is not operating properly it can do odd things. Try disconnecting and plugging both ends of the Waste Gate Hose and see if your smoothes out your Boost.

Even if your ALDA was disconnect and the Hose plugged as the Engine rpms go up I would expect the Turbo Boost to also go up.

See if there is a DIY on testint the ALDA for leaks.

Maybe there is some issue with the Turbocharger.

I think I mentione Manifold leaks in another thread of yours. When I removed My Manifolds I found that the Exhaust Manifold was warped. I think the Intake was also but not nearly as bad.

[Zacharias]

Stu Ritter, who was a former Mercedes dealer tech who once co-moderated a discussion group, used to say that:

- The ALDA is properly adjusted when you can just see smoke in the rearview mirror on HARD acceleration in daylight,

- Many turbodiesels came from the factory with the ADLA way out of adjustment (well under spec), and

- About 1 in 10 ALDAs break as soon as the adjustment screw is turned (BTDT).

If your car never smokes it suggests the ALDA is broken.

[Silber Adler]

thanks for the interesting comments.

911: Yes I recall you mentioning a warp in the manifold. I have not really investigated that. Except to say that I am not seeing a load of black crud which I would expect to see on the exhaust side and possibly on the intake side, well before I blocked the leaking egr. The ALDA pressure relay is on the firewall nearly behind the brake booster?

vstech: unbolt it from the IP. Do I need to put a cover plate on the IP to cover the hole.

Maybe the ALDA is broken. I see some at startup but once rolling I never see any in the mirror.

The car is running better than it was.

I am pretty sure that the waste gate is working as It will go up to 9 as soon as I give it enough fuel (say 3/4ths throttle) to get to 26-2700 or more. It never goes above that.

[Brian Carlton]

Originally Posted by Silber Adler

As I am gently accelerating...........

Those five words tell the entire story.

When you're using a fraction of the available horsepower, the turbo might not put out much boost pressure at all. In fact, if the Bowden cable is setup properly, the engine will shift at about 1800-2000 rpm...........well out of the capability of the turbo to provide much of anything.

Without some boost, the ALDA won't provide fuel, and doesn't need to provide fuel because the driver isn't demanding the horsepower.

If you want to test the ALDA, confirm that it sees 12 psi at 3000 rpm in third gear with the pedal on the floor. If it does not..........and it likely will not...........you need to do a wastegate adjustment.

[Doktor Bert]

Originally Posted by Brian Carlton

If you want to test the ALDA, confirm that it sees 12 psi at 3000 rpm in third gear with the pedal on the floor. If it does not..........and it likely will not...........you need to do a wastegate adjustment.

Agreed....

I am running my ALDA screw all the way out CCW with a full 3.0mm of shims under it. IIRC, 1.0mm of shims is equal to about 1 turn of the adjustment screw. So, I backed my screw out 3 full turns and gave the ALDA another 3 turns (in theory) with shims...

[Silber Adler]

Interesting. You raising the ALDA off of the IP with the shims. I would say the the 6mm thread is about a 1mm so your measurements sound about right.

At what point does it become fairly non functional.

Originally Posted by Doktor Bert

Agreed....

I am running my ALDA screw all the way out CCW with a full 3.0mm of shims under it. IIRC, 1.0mm of shims is equal to about 1 turn of the adjustment screw. So, I backed my screw out 3 full turns and gave the ALDA another 3 turns (in theory) with shims...

[Doktor Bert]

Not sure...

I know I get a pretty good stream of black smoke at WOT where I am now and if I go further, the smoke is really bad. Right now it is a fairly good balance of power to smoke...

[Silber Adler]

Brian, My question is why the big S curve in response. 0, 1, 2, then shooting to---->6 with nearly constant pressure on the foot feed. It will go from 5-6 to 9 in another second if go to say half throttle. Is that what your car does? I wouldn't think the the max pressure that the waste gate kicks in would have much to do with the lag.

Yesterday I was on the divided highway cruising at 1-2 psi at 60 mph on a flat road running 2600 rpm. I was driving for economy. If I was at 1psi I could keep it below 2psi without trouble. Once I got it over 2 it would cut in and go to 5-6. As sudden and as non linear the pressure goes to 6 it feels like the fueling system is being held back by what I presume to be the ALDA. Perhaps it is wear. At no time could I hold the throttle to 3 or 4psi.

What brought this up was that this trip was the first time that I have been driving for economy. My first three fills have been averaging 28 mpg running 65 mph with definite testing bursts.

Originally Posted by Brian Carlton

Those five words tell the entire story.

When you're using a fraction of the available horsepower, the turbo might not put out much boost pressure at all. In fact, if the Bowden cable is setup properly, the engine will shift at about 1800-2000 rpm...........well out of the capability of the turbo to provide much of anything.

Without some boost, the ALDA won't provide fuel, and doesn't need to provide fuel because the driver isn't demanding the horsepower.

If you want to test the ALDA, confirm that it sees 12 psi at 3000 rpm in third gear with the pedal on the floor. If it does not..........and it likely will not...........you need to do a wastegate adjustment.

[Diesel911]

Originally Posted by Silber Adler

thanks for the interesting comments.

911: Yes I recall you mentioning a warp in the manifold. I have not really investigated that. Except to say that I am not seeing a load of black crud which I would expect to see on the exhaust side and possibly on the intake side, well before I blocked the leaking egr. The ALDA pressure relay is on the firewall nearly behind the brake booster?

vstech: unbolt it from the IP. Do I need to put a cover plate on the IP to cover the hole.

Maybe the ALDA is broken. I see some at startup but once rolling I never see any in the mirror.

The car is running better than it was.

I am pretty sure that the waste gate is working as It will go up to 9 as soon as I give it enough fuel (say 3/4ths throttle) to get to 26-2700 or more. It never goes above that.

I only mentioned it after someone else did as a sort as to why people wrap the Manifold.

I don't think there is any room to do such a thing on a Mercedes and I doubt if it would help much as the Manifold is fairly short.
That sort of stuff was typically done on V-8s where the Hot Rodder had the Headers/Exhaust Manifolds made of Tubing and due to the length of the Tubing to connect both Cylinder Banks to one Tubo I guess it was possible to lose a lot of exhaust gas heat and therefore pressure and volume.
I think they also have wraps for the Turbocharger Exhaust Housing.

Wrapping the Exhaust Manifolds in the above case helps to keep the heat in the exhaust gas and preserve the velocity of the gas.

Your are more likely to see the Exhaust Wrap as a protection from a fire or burns on Boats.

If you don't cover the Hole after the ALDA is removed I would suspect there is going to be a mess of Oil because the Governor Weights are going the fling a lot of Oil around.

Things that could go into the hole could mess up the Governor if they are large enough and the Crankcase if they are small enough.
Also if your Engine has Blow-by that will come out of the Hole also.

[oldsinner111]

my ALDA at the landfill,I like smoke

[Diesel911]

Originally Posted by Silber Adler

Brian, My question is why the big S curve in response. 0, 1, 2, then shooting to---->6 with nearly constant pressure on the foot feed. It will go from 5-6 to 9 in another second if go to say half throttle. Is that what your car does? I wouldn't think the the max pressure that the waste gate kicks in would have much to do with the lag.

Yesterday I was on the divided highway cruising at 1-2 psi at 60 mph on a flat road running 2600 rpm. I was driving for economy. If I was at 1psi I could keep it below 2psi without trouble. Once I got it over 2 it would cut in and go to 5-6. As sudden and as non linear the pressure goes to 6 it feels like the fueling system is being held back by what I presume to be the ALDA. Perhaps it is wear. At no time could I hold the throttle to 3 or 4psi.

What brought this up was that this trip was the first time that I have been driving for economy. My first three fills have been averaging 28 mpg running 65 mph with definite testing bursts.

This post explains it better to Me.

Somewhere above 2 psi the ALDA is suddenly alowing a enough Fuel that it suddely making the Boot jump up quickly.
I have never checked mine so I don' know if that is the normal way it works.

But, you would think that if the above is the case decreasing the amount of Fuel that the ALDA allows would also decrease the Boost from jumping like it does.
Another issue could be that the ALDA is simply old and stiff causing it not to expand smoothly.

Somewhere in the IP there is a Spring that the ALDA is working against. Perhaps that Spring is old and weak.

[Brian Carlton]

Originally Posted by Silber Adler

Brian, My question is why the big S curve in response. 0, 1, 2, then shooting to---->6 with nearly constant pressure on the foot feed. It will go from 5-6 to 9 in another second if go to say half throttle. Is that what your car does? I wouldn't think the the max pressure that the waste gate kicks in would have much to do with the lag.

This is quite typical of a turbo's response. You get very little response at lower rpm's and then, in a very short period of time, the rpm's climb into the area where the turbo can spool and the boost climbs accordingly.

You're correct about the wastegate.

[Silber Adler]

I have researched this and have come up with a new theory for the sudden jump in boost. The Air Recirculating Valve. It is shown in this picture with the blue vacuum line going to it.


The ARV allows the turbo to wind up some by dumping air across the compressor side of the turbo. When the valve closes the turbo is already wound up causing a big increase (4-6psi) in boost quite suddenly.

I read that they added the ARV to 85s because they have a taller axle ratio and could use a bit of jump in turbo boost. I plan on blocking the line to ARV to test my theory to see if it steadies the boost change.