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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 03-14-2011, 07:20 AM
VitaminXX VitaminXX is offline
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DISA Activation Fail

Went to a garge for a regular maintanence today. I asked in what situation the DISA is replaced. The mechanic used an oil-pen and marked a white point on the DISA valve, like the picture below. He told me normally when I start the engine up and step on the gas to let the RPM up to around 3000, the white mark should move to right accodingly since the DISA is regulating the air flow. However, as I step on the gas, the white point did not move to right. The mechanic unplug the DISA terminal, nothing happened. The mechanic applied an external 12V power source to activiate the valve, the white mark did not move also. He told me my DISA is bad.

http://i1202.photobucket.com/albums/...immer/DISA.jpg
When I got home, I used my GT1 to activate the DISA valve, it seems the white mark did not move either.

Does this mean that my DISA is bad?
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  #2  
Old 03-14-2011, 07:52 AM
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16valex 16valex is offline
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I thought it was 4000 RPM is when it start to move.
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  #3  
Old 03-14-2011, 08:21 AM
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bluebee bluebee is offline
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Quote:
Originally Posted by 16valex View Post
I thought it was 4000 RPM is when it start to move.
I didn't know about the 'white point' trick; but we have reasonably well characterized how the DISA operates over in these threads:

- DISA VALVE FLAP BREAKS: the DIfferenzierte SAuganlage ("Differential Air Intake") valve flap breaks (1), sometimes with parts sucked into the intake manifold (1) (2) (3) (4) (5) (6) (7) (8) or the disa valve o-ring fails (1) (2) & where to get just the DISA valve o-ring (1) & how the DISA valve operates (1) (2) (3) & an example of how a broken DISA valve can ruin your engine (1) & how to test DISA operation (1) or temporarily repair your DISA valve for free (1)

Without re-reading those threads, I 'thought' all the motion was internal (i.e., the valve spins inside the intake manifold); but I point the OP to those threads to ascertain why the external white dot didn't move.

NOTE: I reproduce the photobucket picture here, at 640x480 pixels, for convenience & posterity:
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Old 03-14-2011, 08:32 AM
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bluebee bluebee is offline
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OK, so I couldn't resist looking myself!

On Feb 02, 2011, I had opened a thread on how to test the DISA valve in operation:
- I'm confused how to properly test for DISA valve proper operation on the BMW E39

I don't think we really got definitive answers. Certainly we didn't get this moving-white-dot trick.

As for the RPM changes, in another thread, RDL kindly notes from pages 42 to 44 of this document (m54x5[1].pdf), the following:
  • below ~ 4000 RPM closed
  • above ~ 4000 RPM open
  • rest position, i.e. when removed - flap open
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Old 03-14-2011, 08:36 AM
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bluebee bluebee is offline
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Digging more (I should have delegated this to the OP!) ... in order to test something, you need to understand how it works ... so here is how the DISA works based on RDL's information.

This is cut and pasted from here:
- When does the intake manifold adjustor (DISA Valve) close?

Quote:
Originally Posted by bluebee View Post
Hi RDL,
Thank you very much for proactive providing the technical information for DISA operation! This is an absolutely astoundingly nice source of learning material!

For convenience of the reader, I've extracted the DISA portion below, verbatim:










In addition, this video should help us understand DISA operation a bit more:
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Old 03-14-2011, 10:32 AM
VitaminXX VitaminXX is offline
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Thanks Bluebee.
From the doc. above, my understanding is the flap in the DISA is normal open when the car is off, and it is close as the engine is start up since the rpm is lower than 3750. The functiopn of DISA is to regulate the air intake path to make a long path for air to increase torqe when low rpm.
The white mark is on the rod which was pulled by a motors(??) and then pulls the flap to close the DISA when low RPM. As I started up the engine, I thought the white mark should be moved to right which means the rod pulls the flap to close. This is my understanding. But, no matter what I did, step on the gas to make the RPM up to 3000, I remember the RPM was over 4000 when testing, or unplug the terminal or applied an external power, 12V, to the DISA. Nothing was changed. Is my DISA really bad? I am not sure.
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Old 03-14-2011, 11:37 AM
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Scottji Scottji is offline
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Quote:
Originally Posted by VitaminXX View Post
Thanks Bluebee.
From the doc. above, my understanding is the flap in the DISA is normal open when the car is off, and it is close as the engine is start up since the rpm is lower than 3750. The functiopn of DISA is to regulate the air intake path to make a long path for air to increase torqe when low rpm.
The white mark is on the rod which was pulled by a motors(??) and then pulls the flap to close the DISA when low RPM. As I started up the engine, I thought the white mark should be moved to right which means the rod pulls the flap to close. This is my understanding. But, no matter what I did, step on the gas to make the RPM up to 3000, I remember the RPM was over 4000 when testing, or unplug the terminal or applied an external power, 12V, to the DISA. Nothing was changed. Is my DISA really bad? I am not sure.
I think the DISA is all internal moving parts. Any driving symptoms? When my DISA went bad, it was apparent something was wrong -- rough idle, whistling/chirping noise, SES light, many symptoms similar to an intake leak. If you aren't experiencing any problems, I think it's probably okay, and my vote is to leave it alone.

If you are experiencing some problems, I'd inspect it by simply removing the DISA and *gently* checking the butterfly valve for play. It shouldn't take long, have some sensor-safe hi-temp RTV handy in-case the gasket on your DISA is bad and you want to re-install it. While it's out, clean it with some carb cleaner, and gently inspect it -- on mine, the center pin in the butterfly valve was completely broken loose -- the valve just flopped around.

By the way, I talked to a dealer mechanic who said the DISA valves typically have a 100k mile lifespan -- that's about where mine went. It's an easy DIY, although at $200+, the part is a little spendy.
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  #8  
Old 09-29-2011, 01:10 PM
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bluebee bluebee is offline
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Quote:
Originally Posted by VitaminXX View Post
Is my DISA really bad? I am not sure.
I'm trying to put all the DISA diagnostic test procedures in one place:
- How to properly test for DISA valve operation on the BMW

So ...

It would be nice to get a report from VitaminXX as to what the final solution was.
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