Disa removal / delete?
 

Hi guys. Narrowed down rattle noise to the disa unit. It would rattle under load during mid-range acceleration and on start up. Unplugging the electrical connector stopped the rattle whilst driving immediately.
So will be getting it out this week.
I have had an m57n diesel with swirl flaps and from my understanding it's virtually the same flap system.

I followed a guide where a guy cut the swirl flap spindle with a dremel tool and he plugged the hole left behind with a screw and some thread locking compound. So in effect leaving the housing of the swirlflaps in the manifold but just removing the moving part. I did this on my previous car with success and not having to shell out £50 for blanking plates.

I would like to know if this is something I could do with the disa unit? Has anyone tried it? I've done a search and most results are people completely deleting the disa and hoses etc.



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The result would be that you are permanently using the runners that correspond with higher-rpm operations and would lose the resonance at low rpms that boost torque.

In other words you wouldn't like it very much.

Currently I'm running it with the electrical connector unit unplugged so it's not functioning at the moment and tbh I haven't felt the slightest difference in how it drives.

Leading me to believe the unit is dead. I do plan to eventually replace it but for the time being I'd like to remove the moving part as it's rattling and I'm worried it will end up inside the combustion chamber.


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As Crowz said, removing the "flap" will kill low end torque. As you have it now (flap in place but disabled) you are only loosing high end power - something you may not notice in everyday driving.

There's a reason why blanking plates are popular on the M57 engines, rather than just pulling the flap out. ;) (Note: although the swirl flaps in the M57 engines seems similar and produce a similar result they work very differently from a DISA flap.)

And thank goodness the M57/M57N in the E53 seems to have avoided getting the dreaded swirl flaps. :thumbup:

You should rebuild the DISA with a repair kit that will permanently stop the rattle and prevent any parts from entering the air intake manifold.

Here is one example from German Auto Solutions.
https://www.germanautosolutions.com/...sa_kit_diy.php

There are also kits available from other suppliers on ebay or amazon. Make sure you get the proper kit for your vehicle/engine.

I recommend rebuilding the DISA with a kit that includes an aluminum flap and a full length screw/shaft that eliminates the chance of the pin that currently holds the flap breaking loose and falling into your intake. Very bad for your valves. Easy way to test if your DISA is working is to pull it, manually close the flap and put your thumb over the small intake port at the vacuum diaphragm. If it stays closed or close to it, it is working. If not, it needs a new diaphragm. There are rebuild kits out there that include this diaphragm. This shows how to test the DISA on an E46: https://www.youtube.com/watch?v=pg6Jb3qEYvM It's essentially the same valve as the E53. Function is the same. Test demo starts at 1:46.

As mentioned several times, with the DISA valve flap removed engine performance is compromised since you lose low end torque and high end horsepower. Losing torque and horsepower will also negatively impact mileage. Since you have to remove it to remove the flap, I would rebuild or replace it, no exception. When the flap is rattling it should be addressed ASAP. Currently it is a small low cost problem but could become a huge cost issue at any time. It is likely the reason you didn't notice a lose of performance when you removed the flap on your diesel was because it may not have been sealing for some time. IMO you should fix it right rather do a shade tree work around.

While DISA valves and swirl flaps look similar, they work rather differently. The swirl flaps (multiple) in the diesels do not contribute much to power gain - they are more about engine efficiency. Almost no one has ever noticed the removal of the swirl flaps in the BMW diesels, even if removed when working properly.

But while they work differently, they fail in a similar way, with similar results! :yikes:

Lots of info. here: -

BMW diesel engine SWIRL FLAPS - all you ever need to know

It's an interesting read, even if you don't own a diesel. ;)

And since I've gone and hi-jacked Shel's thread, I'll mention that Shel is dealing with the DISA flap on a 3.0i (or at least Shel's previous questions have been about a 3.0i so I'm assuming this question relates to the same car...).

BTW, I always wondered what DISA stands for... Turns out DISA stands for the German “Differenzierte Sauganlage” which basically means Differentiated Intake.

Who knew...? :rolleyes: