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I'm confused how to properly test for DISA valve proper operation on the BMW E39

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89K views 35 replies 14 participants last post by  crazy4trains  
#1 ·
I'm confused how to properly test the DISA valve on the E39.

Today, after seeing ForcedFirebird's pictures of the inside of a bent exhaust and pitted intake valves in the #3 cylinder due to the DISA (DIfferenzierte SAuganlage - "Differential Air Intake") flap failing ... and then moments later, reading of Ågent99's smog-test saga where the DISA valve seemed to have been the culprit ... and then seeing cambrian123456 post where in the process of cleaning the ICV, he notices his DISA valve is filthy ...

And, earlier this week, DominguesE30 asked the similar question of how to test the DISA valve (without much response).

I got to wondering how to "really" TEST the DISA valve in the BMW E39.

Doing the obligatory searching ... I find a confusing jumble of tests:
- These pictures show varnish buildup (presumably that's a visual test)
- This picture shows the flap missing (another visual test)
- Poolman gave a noise/performance DISA test here
- ventsyv added a DISA rattle test here (another noise test)
- Ågent99 alluded to a "smoke test" here (a visual test for vacuum leaks)
- szee1 alludes to the "resistance" of the DISA flap here
- dakarm also alludes to the "resistance" of the DISA flap here
- Lbert says to check the condition of the o-ring DISA gasket here
- uncmozo mentions specific codes thrown here that implicated the DISA valve
- This rebuild DISA article says codes will be your first sign of malfunctioning
- This related DISA article says you'll get a misfire if the o-ring leaks

But I see no real diagnostic tree for the DISA valve.

Maybe it's time to start one?

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#2 ·
Bluebee- I too was plagued by this scenario... I had been battling a pretty bad idle stumble, and I inspected my DISA to the best I understood and had ruled it out-and moved on. When I finally gave up and brought the car in to the mechanic (I thought it was a vacuum leak that I couldn't find) it turned out to be the DISA. The mechanic "bench tested" it somehow. The car is back in the shop today for some unrelated stuff but when I pick it up I'll try to ask him how exactly he tested it.
 
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#3 · (Edited)
It will usually pull intermittent P0171 and P0174 codes (running too lean on bank 1 and 2) - like a vacuum leak. Keyword is intermittent - like once a week. If the interval starts getting shorter you're in trouble.. Also, the DISA starts making noise.
Pulling out the DISA, if the valve is sloppy (no resistance) - she's on the way out.
If you just pull it out to check it, you better have some replacement O-ring which you can source from e-bay seller jdm-auto. Linky.
That is if the DISA is still OK. No sense shelling out 200 bux (yet).

P.S.: for clarification: the first thing to go is the resistance of the flapper. More air gets sucked in - like unmetered air (that's why the codes start popping up). This combined with the noise (you have to open the hood and hear close to the intake manifold. A helper should rev the engine) is a dead giveaway. Doing a vacuum leak test (smoke test) will reveal nothing - pretty much pinpoint the culprit. Also some stumbling when you step on it.
This is all the info I could gather over different forums.
 
#5 ·
An ingenious proposal for testing the DISA valve is in this thread today:
- DISA Activation Fail

The mechanic proposed placing a white dot in the location shown below; then at the proper RPM, the dot should 'move' one way, and then at the next RPM cut point, it should move the other way (the theory goes).

According to RDL, (m54x5[1].pdf), those RPM points are:

  • below ~ 4000 RPM closed
  • above ~ 4000 RPM open
  • rest position, i.e. when removed - flap open
Reference: Pages 42 -44 of the attached document.
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#6 ·
#7 ·
For the crosslinked record, today, this thread shows an important point:
- Bingo!! I may have solved the misfire and lean codes P0171, P0174, P0300

Not only is the DISA responsible for some misfires, but, it can ruin your engine if you don't check it every 100K miles or so.

Image


- Why check the DISA at 85K miles to 90K miles or whenever the airbox is removed (1) (2) & how to repair a rattling DISA unit (1) (2) (3) & 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) & how the disa valve o-ring fails (1) (2) & how it can cause all sorts of cold-engine rough idle problems (1) (2) & where to get just the DISA valve o-ring (1) & how the DISA valve operates (0) (1) (2) (3) (4) & an example of how a broken DISA valve can ruin your engine (1) & how to test DISA operation (1) (2) (3) (4).
 
#8 ·
#10 ·
Since I have the following codes, I decided today to remove my DISA for a look:

  1. P1083,BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
  2. P1085,BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
  3. P0174,BMW 228, System Too Lean (Bank 2)
  4. P0171,BMW 227, System Too Lean (Bank 1)
To remove the DISA was easy.

  • I removed the electrical connector to the DISA
  • With a hinged socket set, I removed the lower T40 Torx bolt
  • I removed the upper T40 Torx bolt
  • I removed the DISA (pressing down on one vacuum wire to provide room)
  • NOTE: I did not remove ANYTHING else (no MAF, no hoses, no battery connection, no nothing)
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The one thing I should have done beforehand is that I should have purchased an aftermarket M54 DISA o-ring:
- Where to get just the DISA valve o-ring (1)

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I wanted to innervate the DISA electrical connection to see if it would operate at either 5 volts or 12 volts; but I figured I'd check here first.

Q: Does anyone know if a 6 volt/12 volt battery charger can be used to test the DISA valve electrical operation?
 

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#11 · (Edited)
bluebee said:
Q: Does anyone know if a 6 volt/12 volt battery charger can be used to test the DISA valve electrical operation?
Click to expand...
It looks like the test is to use 12 volts (based on this thread):
- E39 (1997 - 2003) > DISA Activation Fail

- The 12 volt test
VitaminXX said:
The mechanic applied an external 12V power source to activate the valve, the white mark did not move also. He told me my DISA is bad.
Click to expand...
From that same thread, it looks like these are additional DISA diagnostic test procedures:

- The moving dot test
VitaminXX said:
The mechanic ... marked a white point on the DISA valve... 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 accordingly since the DISA is regulating the air flow. However, as I stepped on the gas, the white point did not move to right.
Click to expand...
- The unplug test
VitaminXX said:
The mechanic unplug the DISA terminal, nothing happened.
Click to expand...
- The GT1 test
VitaminXX said:
When I got home, I used my GT1 to activate the DISA valve, it seems the white mark did not move either.
Click to expand...
And, from post #10 of this thread, comes these two videos for testing purposes:
- X3 E83 (2004 - 2010) > CCV time, oh and DISA too.

- The rattling noise test
poolman said:
the way to make the test is, with the engine at idle lay your left ear over on the disa. If you hear rattling and such inside the box,it's bad and needs replacing.
Click to expand...
szee1 said:
It appears that unplugging the DISA connection should stop the noise.That said, I am not sure that unplugging it always eliminates the noise. I have read that you can also place your ear on the DISA while the engine is running and verify if noise is coming from it. From what I can gather, the failure points can either be a loose valve on the shaft or a failure in the vacuum system which creates the noise. Mine was a loose shaft and I don't recall any noise from it.

This is a good link to show how the valve is connected to the vacuum actuator.

DISA noise video.
http://www.youtube.com/watch?v=IrXhuvgJuqs&feature=related
Click to expand...
The autopsy test:
- E39 (1997 - 2003) > DISA Autopsy

The ribbed-o-ring test:
- E39 (1997 - 2003) > DISA 0 Ring
Image

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#12 ·
You can't test something until you know how it works normally.

To that end, this explanation helps with any voltage tests we may run:
- E39 (1997 - 2003) > DISA Autopsy

AnotherGeezer said:
After much research I found this to be the best DISA operation description I could find.

"The disa valve has an outer seal (inside the manifold) and a diaphragm inside the valve itself. The valve is constantly fed 12 volts during normal throttle operation and then open circuits on higher RPM and throttle opening. This deenergises the coil which stops the manifold vacuum from reaching the diaphragm. The butterfly then springs open."
Click to expand...
 
O
#13 ·
Hey guys I too am confused. I've been getting the check engine light and P0171 and P0174 codes, over the last 20-30k miles, with it gradually coming on more frequently. The light comes on sooner, the colder the weather, if temps are above 15 degrees although codes come up, the "check engine" light will not. the car appears to runs fine, except for in winter when temps go below 5-7 degrees C, and when until its fully warmed up, the idle bounces up and down a little when I come off the gas to a stop.

http://www.youtube.com/watch?v=9DuAt5p3Wnw&list=UUl4kj0pLPCOfCEdtg6qGWCA&feature=share

My peake tool gives me:

Table 19
E3 is O2 sensor adaptation limit Cyl # 1-3
E4 is O2 sensor adaptation limit Cyl # 4-6

Here's a video of my DISA, yes its long vid, but essentially the pin is fine, the flap doesn't rotate freely, and moves the piston towards the vacuum pot. BUT the vacuum pot doesn't appear to hold position at 45 degrees

http://youtu.be/UWyW5rSCByc

I'm just surprised that all other aspects of my DISA after 122k miles appear fine and that its the vacuum pot that's the cause of my codes and rough idle in cold weather. Any other checks I can do? Might try the white dot test.

Additionally:
MAF has been cleaned
CCV system completely overhauled (this actually decreased the frequency of the codes and engine light coming especially in the warmer weather last summer. And I've been through whole install again to make sure everything was connected up right)
Minor valve cover gasket leak (oil consumption well under 1 litre per 1000 miles)
 
#14 · (Edited)

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M
#25 · (Edited)
Hi,

There's some info on applying voltage to the DISA, but I don't see any on "if" or "when" voltage is applied at the connector (car side). I've seen a video of an M54 325 (e46 I think) where he puts key into run position and his DISA moves. I did the same on a new DISA e39 and no movement (while disa out of car). I have no one with me to watch to see if it moves while revving. So question is, at what point is voltage applied to the connector? In run position? when started? when started and revving?

UPDATE: Zero voltage with car off, 12V in run position. I didn't (forgot) to check with car running. But there is voltage in run position. So it's odd why a brand new DISA doesn't move like a video I saw online.

UPDATE2: and now I know why. that video I mentioned above must have had some vacuum built up inside already. Fast forward to 2:30 to understand why. :) https://www.youtube.com/watch?v=pg6Jb3qEYvM
 
#17 ·
I never did fully understand how to test the DISA, and I see you opened a good thread over here today...
> E39 (1997 - 2003) > somebody help me with DISA valve
gvelco said:
first of all i know how disa operates.for example it consist of main components:hex head crank bell,flap and vacuum.
there is nothing problem with my disa unit,why doesn't it work??(i mean "piston" isn't moving and it is always open position|)
i tied up plastic piston with wire to hold flap closed,let see if it gains torque at low rpms.
Click to expand...
 
O
#18 ·
Just an update, at 128k my car was due replacement of its precat oxygen sensors, and this seems to have resolved the problem of P0171 & P0174...... for now. Longterm fuel trim are both approx at -/+ 5%. So far all has been running well, but in the last week temps have dipped below 9 deg C, and the idle has started to become a little uneven again from a cold start, but no codes yet. The ultimate test will be to see how the car runs when temps drop below 0 deg C.

I managed to get a used DISA in good working order, better than the original one currently installed on my car. If codes appear again as temps fall, I'll install it and see if that further improves things.
 
#19 ·
For cross reference, someone asked for clarification on the DISA bolt size today...
> E39 (1997 - 2003) > DISA/ICV Bolt Head Size?

mattmar1 said:
Needing to remove the DISA on my 03 525i...many threads/vids say the right driver to remove the bolts is a T40..not even close. On my 99 528i, I was able to remove the DISA bolts and the ICV bracket bolts with a T30, though not a perfect fit. The 525 has the same bolt head size as the 528 did, however when trying them with the T30, the tension feels close to rounding off the driver and bolt heads, so I backed off going further. I once saw in a thread somewhere that it takes an oddball driver to remove these bolts, however at the time I did not annotate the name/size. I've been searching for a week to find out what this driver is to no avail. Anyone have any thoughts to this matter?
Click to expand...
 
#20 ·
The DISA smoke test is for Vacuum leaks, ie ruptured diaphragm, o ring fail. I saw a video once on youtube in which the smoke test was done peripherally to other checks..as it's not listed as a smoke test, I am trying to find it. Basically, all the ducting was removed, a plug was installed in to the intake, and hooked to a smoke generator, which injected smoke in to the manifold. The smoke leaked from a faulty DISA valve diaphragm opening. This generator as shown was a specialized piece of equipment.
 
#21 ·
mattmar1 said:
This generator as shown was a specialized piece of equipment.
Click to expand...
A smoke test is so useful, we should have better plans for building/buying our own for less than $50...
- How to make your own smoke machine (1)
 
K
#22 ·
DISA preventive maintenance

Changed the DISA yesterday with the G.A.S. M54 DISA Valve Repair & Upgrade Kit
 and the DISA Housing Fluorosilicone Replacement O-Ring.

While I didn't have any noticable wear or problems with the DISA I decided to do the upgrade any way.

The DISA flaps and structure was covered in a light dried oil crust which I cleaned during the upgrade.

When mounting the DISA valve back on the intake I noticed the same oil crusting inside the intake. I was unsure if it was thick so I didn't try to remove it in fear of chunks ending in the cylinder.

Sorry for the poor quality.
Image


I found this image from this thread which show considerably less crusting.
Image


Question is, is this normal? What causes it? And what (if anything) should I do?
 

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#29 · (Edited)
Should the DISA be changed as preventative maintenance? I have all the service records of my car since 2001, and have nothing stating the DISA was changed. I get great gas mileage and my only "issue" is the cold engine dips which ive come to learn/think would be the VANOS unit which will get replaced in a month or two.

Are the DISA valves between the M52TU and the M54 similar in break down?..mine has the seriviceable green O-ring, unlike the orange silicone ring on the M54 units. Most of the info i see here discuss the "newer" DISA units.

Current mileage 144k, 2000 528i M52tu
 
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#31 ·
No. However, you should remove it, slowly, and make sure that the pin holding the vane is not failing or failed. You also want to make sure the o-ring has a good seal. If not, you can buy a Viton o-ring which should last much longer. You will need to cut out the original o-ring on DISA units with the orange, integrated o-ring. Then do this test:
https://www.youtube.com/watch?v=so6xLmg1zno

I do this each time I change the oil.
 
#35 ·
RobinW said:
https://www.germanautosolutions.com...ons/disa_products/m54_m52tu/m54_disa_repair_kit/product_m54_disa_repair_kit.php

This Repair kit works.

Fixing the Vanos made a huge difference to mine.
Adjustable valve timing. Vroooooom
Those nitrile rubbers turn to backbite.
So do the cover gasket rubbers.
And the oil unit gasket.
And even on their bikes.
Click to expand...
I was looking at that repair kit from them, but its specifically for M54's. I have yet to pull out the DISA, will do once rain goes away. The VANOS will be getting done soon, already talked to my Indy about it =)
 
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