M44 DISA Valve Diagnosis

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BonBon
Joined: Tue 08 Jan, 2008 21:10
Posts: 1227

  Z3 roadster 1.9

M44 DISA Valve Diagnosis

Post by BonBon »

My DISA has been clicking quite loudly for a while and I'd like to take it out and have a look before I replace it.
Has anyone removed a clicking M44 DISA and diagnosed the problem?
(From the comment on the end of the following thread it seems that he had a cracked housing but not sure about a "cracked rubber valve" as the vac chamber is enclosed in a hard black plastic enclosure.http://www.zroadster.net/forum/viewtopi ... se#p351903)
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colb
Joined: Sat 05 May, 2012 22:46
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  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: M44 DISA Valve Diagnosis

Post by colb »

Take it out and check it for cracks, you can apply 12v to the terminals to check how it activates and see what is causing the noise, most likely its worn, best replace it if that is the case you don't want it falling apart and sucking debris into the engine.

Colb
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
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BonBon
Joined: Tue 08 Jan, 2008 21:10
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  Z3 roadster 1.9

Re: M44 DISA Valve Diagnosis

Post by BonBon »

I'll have a look tomorrow and take some pics if I see anything.
As it only gets "activated" at 4200rpm my guess is that it's fluttering at all the lower rpms without doing anything.
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BonBon
Joined: Tue 08 Jan, 2008 21:10
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  Z3 roadster 1.9

Re: M44 DISA Valve Diagnosis

Post by BonBon »

BTW - when applying the 12V - is it clear which contact is the plus? (I don't want to risk damaging the solenoid)
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BonBon
Joined: Tue 08 Jan, 2008 21:10
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  Z3 roadster 1.9

Re: M44 DISA Valve Diagnosis

Post by BonBon »

I removed my DISA and all looks fine 315kkm (PN 1247202). Compared to a newer used DISA (110kmile from ebay $50 - newer PN 1438404), the plastics etc. and vac integrity (sucking from the small hole on the bottom) were the same - so there was no immanent disaster awaiting (and it's been like this for at lease 100kkm) . The only difference I can see - is that on my DISA the movement of the flap up and down was 1mm as opposed to 0.5mm on the newer one - and it made a louder clicking when moving it manually up and down the rod running through its center. This was due to movement of the metallic retaining ring that holds the rod in place which seemed to move outward (as can be seen from pics below).
Upon inserting the newer DISA the noise disappeared.
I tried applying 12V to the older DISA. The flap closed "once and half" and then it no longer managed to close the flap when 12V applied - it clicked with the 12V and held it partially closed if I closed it manually. I hope I did not damage the solenoid/pump while testing with my haphazard wires (it did not matter which way I connected plus and minus, it behaved the same). I did not want to test on the newer one in case I'll damage it.
So not really sure what the clicking was. According to this link http://www.bimmerwerkz.com/forum/3-seri ... 29171.html at low RPMs the flap is normally closed by the ECU supplying 12V and then open circuit and opens at ~4000rpm. He claims one should feel the difference when hitting the high RPMs and fuel economy is better with a good DISA. I did a test drive and did not feel any difference so my bet was that the operation was OK and the wiggling caused the clicking... (I have no idea about the testing :shrug )
(I will follow the effect on petrol consumption on a separate thread http://www.zroadster.net/forum/viewtopi ... =5&t=42713)
PICs
Side by side (identical - ignore the angle of the pic)
Image
Old one - retaining ring at surface of black plastic
Image
newer one - retaining ring 0.5mm deeper
Image
Last edited by BonBon on Wed 10 Jun, 2015 16:16, edited 3 times in total.
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colb
Joined: Sat 05 May, 2012 22:46
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  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: M44 DISA Valve Diagnosis

Post by colb »

Looking at the pictures the old one looks well worn at the pivot point and the play you detected would be the cause of the clacking noise, your replacement having stopped any clacking noise would seem to verify the wear issue with the old one.
I don't think connecting + and - on wrong terminals would have damaged it, it may be the case it just chose to pack up when it did.
As it is now silent in operation I think you have cured it.

Colb
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
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BonBon
Joined: Tue 08 Jan, 2008 21:10
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  Z3 roadster 1.9

Re: M44 DISA Valve Diagnosis

Post by BonBon »

Just to be clear. Looking at the pictures the movement/play was moving the flap towards and away from you up and down (and not left and right). I probably could have fixed it by knocking the ring downwards and securing it in place.
BTW - I have not found a definitive link of somebody who shows a DISA closing by applying 12V
Last edited by BonBon on Wed 10 Jun, 2015 16:17, edited 1 time in total.
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BonBon
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  Z3 roadster 1.9

Re: M44 DISA Valve Diagnosis

Post by BonBon »

1. The closest I have seen to a recommended bench test is the following link - that you need to have vacuum first and then apply the 12V - and here he also experienced something similar to me - that it seems to do something first time and then just clicking of the solenoid. http://www.bimmerfest.com/forums/showth ... p?t=830977
2. Although with a different DISA - the testing also seems connected with vacuum (but I have no idea what the vac line is doing) and then by removing the 12V it allows the flap to move. Obviously more convoluted than simply moving the flap with 12V. https://www.youtube.com/watch?v=1GnCw44ezeU
3. .....so my old DISA is probably still OK - just a bit wiggly.......
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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
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  Z3 roadster 1.9

Re: M44 DISA Valve Diagnosis

Post by BladeRunner919 »

In INPA you can active the DISA, so that could be done with it removed, I guess. I'll have a go sometime out of curiosity.
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BonBon
Joined: Tue 08 Jan, 2008 21:10
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  Z3 roadster 1.9

Re: M44 DISA Valve Diagnosis

Post by BonBon »

I have a DISA that I'm happy to bench test and/or sacrifice for the sake of humanity. Strange that over the years nobody seems to have documented a complete description of operation - and many have been stumped. (I recall encountering a simar problem with the heater core valve which was pretty simple - but it confuses people when things are normally closed as soon as you turn on the ignition and connected in series with te microswitch on the back of the temp dial)
It seems to me that the DISA operation is a bit more complex than simply applying 12v and somehow the manifold vac and/or pressure move the flap and perhaps the solenoid is a simple valve (and not a pump) that maintains and releases vac/pressure together with the one way valve on the back of the DISA.
If I had more spare time I'd figure it out. At this point I'd prefer some hints.
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BonBon
Joined: Tue 08 Jan, 2008 21:10
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  Z3 roadster 1.9

Re: M44 DISA Valve Diagnosis

Post by BonBon »

I've finally found decent info on how to bench-test the DISA. See the post by G13N
http://www.bimmerforums.com/forum/showt ... ve-problem.
In fact the solenoid is a simple valve - and many click when they work.
Another good thread: https://youtu.be/q86gvOYrVw0. The vacuum to close the flap comes from the manifold when the DISA is installed.
The only thing I don't get is where did the 'vacuum' come from to close the flap the first time I gave the removed DISA 12V?
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