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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 10-16-2011, 01:19 PM
seemyad's Avatar
seemyad seemyad is offline
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Location: Seattle WA
 
Join Date: Jul 2011
Posts: 600
Mein Auto: 530i Sport Package
How To Check Your DISA - 5 (fairly) Simple Checks

- Blubee -

Can we get some volunteers to ohms check their new DISA solenoid "magnetic" switch so that be can add what the resistance should look like?

BTW, this check was made possible via Blubee's tenacity for understanding how things work coupled with team work from various BF members. BRAVO!!!


- ALL BIMMERFEST MEMBERS -

You can do two separate electrical checks with a DVM as well as two physical checks by hand (video below shows checks by hand).

1) POWER CHECK - (ENGINE OFF) Disconnect and check the pins on the plug that connects to the DISA. (ENGINE ON at idle) See if it has 12 VDC (or so) on it. If you do NOT have the 12 VDC (or so) then the DISA is NOT receiving the needed voltage to close the internal solenoid switch. Make sure your meter is on DC and not AC (I make this mistake too often).

- DETAILS VIA BLUBEE -

TEST: DISA 12 VOLT HARNESS SIGNAL TEST:
  1. With the engine off, remove the DISA harness connector

  2. Connect your voltmeter to the harness connector terminals

    • Place a red insulated wire in the positive terminal of the DISA harness connector

    • Place a black insulated wire in the negative terminal of the DISA harness connector

  3. Start the engine and idle; you should measure 12 volts DC

  4. (UNSURE ABOUT THIS) Have an assistant rev the engine to 4000 RPM; at 3,750 RPM you should see the voltage drop to zero volts DC
- END DETAILS VIA BLUBEE FOR CHECK 1 -



Checks continued -

2) OHMs CHECK - On the DISA unit itself ohms check the pins that the connector plugs into (engine off). The 12 VDC connector feeds a solenoid switch located inside the DISA. I BELIEVE this switch to be a coil. ALL coils should have a level of resistance through them. When coils go bad they either OPEN (infinite resistance/ohms) or SHORT (far less resistance/ohms than expected). If this is the case the internal switch won't work. My new DISA out of the box read 44.2 ohms both directions. My old DISA (still on engine and) read 55 ohms (the egine is still very hot so will recheck it later).

3) DIAPHRAGM CHECK - (1st video below). If the power to the switch is good AND the DISA switch itself works, the 3rd component is the diaphragm chamber. The DISA needs a vacuum which forces a diaphragm to close the flap. The switch could work but the diaphragm or housing could have a leak i.e. torn diaphragm or cracked housing. Try the test in the 1st video below for this.

4) FLAP CHECK - (2nd video below). The flap should NOT spin freely as it should be locked onto the yellow shaft. If all else works BUT the flap is not locked onto the shaft the flap will never close.

5) VISUAL INSPECTION - Check housing for cracks. Check the pin on top of the flap (is it securely in place?). In it's relaxed state does the flap open a full 90 degrees without you having to move it there? Does the yellow shaft look like it is one opening away from falling off? Are there any signs of corrosion on the terminals? Is the reddish/orange O-ring in good condition providing a good seal between the DISA and the manifold?


Removing DISA

http://www.bimmerfest.com/forums/att...4&d=1319066444

Note: May need to loosen MAF/Air intake hose for room to remove the DISA


Testing the Diaphragm Seal




Free spinning DISA flap. Video shows points of failure toward the middle.






Additional Links -

Strange results from a simple test of the M54 DISA valve today
http://www.bimmerfest.com/forums/sho...413&highlight=

Computer Diagnostic Screenshots
http://www.bimmerfest.com/forums/sho...558&highlight=




NOTE: This post will be modified upon receipt of any new information.

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Last edited by seemyad; 10-19-2011 at 04:23 PM. Reason: DISA, check, test, test DISA, check DISA
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  #2  
Old 10-16-2011, 03:36 PM
bluebee's Avatar
bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
 
Join Date: Mar 2008
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Mein Auto: 02 BMW 525i M54 auto 130K
I love working with the best of the best to figure out how things, such as the DISA, actually work.

Once we know how it works, the tests should just fall out from that.

Since I just removed my DISA last week, I'm not wanting to remove it now (and introduce vacuum leaks); but I can check the resistance in situ- and, there are over 100 people on the DISA group buy who can run the tests of the vehicle.

In addition, I'll see what makes sense to bring over from these threads:
- How to test DISA operation (0) (1) (2) (3) (4)

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  #3  
Old 06-23-2013, 03:09 PM
PatmanBMW PatmanBMW is offline
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Location: California
 
Join Date: Mar 2009
Posts: 19
Mein Auto: 2001 525iT
My 2001 525iT is "burping" some system lean messages on bank 2 and misfires that are not cylinder specific. In chasing down the problem, it has led me to reading what feels like 50 or so posts about the DISA.

The problem is intermittent and is reliably caused under high acceleration. In other words, the car seems to run fine and then doing something like hammering the throttle to pass causing the codes and the car then runs like crap (almost a high speed limp).

I have pulled the DISA and it doesn't look to bad. There is a little bit of oily crap. No cracks. The O-ring doesn't look healthy and could have a had a small leak.

The biggest question is to validate the picture Bluebee posting back in 2013. There are 2 holes that control air/vacuum flow. When covering the larger hole, the flap closes slightly and then holds. There is a noise in the diaphragm when the air is release. It is rubber moving as the air is released. The picture above indicates that when covering the small hole in the area of the flap, it should also hold the flap. Mine doesn't do that.

Could someone validate that covering the small pin sized hole should hold the flap closed?
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  #4  
Old 11-05-2013, 08:28 AM
bluedevils bluedevils is offline
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Location: USA
 
Join Date: Nov 2013
Posts: 16
Mein Auto: 2001 525i Touring
Dumb question but after reading dozens of threads about DISA and other lean code-related problems, I'm not sure of this. If removing the DISA to do a quick visual/physical check, one should install a new O-ring gasket when connecting the DISA back to the motor, correct?

185k miles on my 2001 525iAT, bought it @ 119k. Really want to get to the bottom of my car's numerous trouble codes. Haven't checked the DISA yet but suspect it needs new internals (considering the German Auto Solutions DISA repair kit) and my car probably needs new CCV system as well. Recently had shop replace spark plugs and pre-cat O2 sensors, not expecting it to resolve the trouble codes and oil consumption (approx 1 quart every 1000-1500 miles), and it didn't. Driveability and fuel economy still seem fine. Worried about catastrophic failure due to pin from DISA falling into the combustion chamber.
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  #5  
Old 11-05-2013, 01:53 PM
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bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
 
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Mein Auto: 02 BMW 525i M54 auto 130K
Quote:
Originally Posted by bluedevils View Post
one should install a new O-ring gasket when connecting the DISA back to the motor, correct?
Yes.


See:
- Where to get just the DISA valve o-ring (1)
__________________
Each repair should invariably add to our knowledge base by the process of inexorable incrementalism.
Your job, in return, is to read the suggested threads, where the best people will always add value to those threads, either by pictures or by descriptions, so the next person with the same problem stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need
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  #6  
Old 11-05-2013, 03:38 PM
bluedevils bluedevils is offline
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Location: USA
 
Join Date: Nov 2013
Posts: 16
Mein Auto: 2001 525i Touring
Quote:
Originally Posted by bluebee View Post
Yes.


See:
- Where to get just the DISA valve o-ring (1)
Thanks for all you and others have done to provide such great info on this site. I'm debating whether to order the DISA repair kit from G.A.S. before checking my DISA valve, or just ordering a couple O-rings first.
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  #7  
Old 11-12-2013, 06:43 PM
bluedevils bluedevils is offline
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Some people just aren't meant for DIY automotive work

(deleted)

Last edited by bluedevils; 11-12-2013 at 07:04 PM. Reason: I'm REALLY an idiot
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  #8  
Old 11-12-2013, 07:02 PM
bluedevils bluedevils is offline
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(deleted)
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  #9  
Old 04-13-2014, 04:11 AM
oz striker oz striker is offline
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Location: London, UK
 
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Posts: 25
Mein Auto: '00 330Ci, '07 350Z
Quote:
Originally Posted by bluebee View Post

Can someone confirm that covering up the hole shown in the picture should result in the flap NOT moving at all? When I cover up this hole, the flap immediately springs back.

The other test is to place the finger on the hole on the underside of the DISA (0.53 secs in video below) and even it results in the flap opening to 45 degrees.


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Last edited by oz striker; 04-13-2014 at 04:57 AM.
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  #10  
Old 08-14-2014, 06:31 PM
bluebee's Avatar
bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
 
Join Date: Mar 2008
Posts: 20,996
Mein Auto: 02 BMW 525i M54 auto 130K
See also:
- Where to get a proper DISA valve repair kit (1) & how some jury-rig 'repair' a rattling DISA unit (1) (2) (3) & how the DISA valve operates (0) (1) (2) (3) (4) & how to test DISA operation (0) (1) (2) (3) (4) & a simple DIY to install an M54 DISA (1) & a nice DISA autopsy (1) (2) & a great DISA group buy (1) & how the disa valve o-ring fails (1) (2) & how it can reputedly cause all sorts of cold-engine rough idle problems (1) (2) & where to get just the DISA valve o-ring (1) & why you want to check the DISA at 100K miles or whenever the airbox is removed (1) (2) & why 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) & a well documented example of how a broken DISA flap can ruin your engine (1) & yet another seemingly complex set of misfire codes reputedly traced to a broken DISA valve (1)
__________________
Each repair should invariably add to our knowledge base by the process of inexorable incrementalism.
Your job, in return, is to read the suggested threads, where the best people will always add value to those threads, either by pictures or by descriptions, so the next person with the same problem stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need
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