# M54 engines DISA flap coming apart resulting in engine damage



## BMW_tech (Sep 20, 2007)

I just wanted to share a recent "discovery" and increase in the number of vehicles found with faulty DISA. Only one vehicle had resulted in replacing the complete engine. This is just in my shop. I'm sure other techs and owners here had this experience already.

The flap is powered close, controlled by the DME. Most of you who aren't familiar with the resonance system, here are some words of wisdom :
----> The resonance system provides increased engine torque at low RPM, as well as additional power at high RPM. Both of these features are obtained by using a resonance flap (_in the intake manifold_) controlled by the DME.
During the low to mid range rpm, the resonance flap is closed. This produces a long/single intake tube for velocity, which increases engine torque.
During mid range to high rpm, the resonance flap is open. This allows the intake air to pull
through both resonance tubes, providing the air volume necessary for additional power at
the upper RPM range.
When the flap is closed , this creates another ***8220;dynamic***8221; effect. For example, as the intake
air is flowing into cylinder #1, the intake valves will close. This creates a ***8220;roadblock***8221; for the rushing air. The air flow will stop and expand back (_resonance wave back pulse_) with the rushing air to cylinder #5. The resonance ***8220;wave***8221;, along with the intake velocity,
enhances cylinder filling.
The DME controls a solenoid valve for resonance flap activation. At speeds below 3750
RPM, the solenoid valve is energized and vacuum supplied from an accumulator closes
the resonance flap. This channels the intake air through one resonance tube, but increases
the intake velocity.
When the engine speed is greater than 4100 RPM (_which varies slightly - temperature influenced_), the solenoid is de-energized. The resonance flap is sprung open, allowing flow through both resonance tubes, increasing volume.

The problem I have seen with the part is that the metal pin that holds the flap together comes apart falling out of it's place. Not only does the flap stops working, the pin can fall down into the combustion chamber and finds its way in between the valves and the piston creating HAVOC. Valves can bend and the cylinder walls can be damaged when the pin falls off. I am not sure if fuel quality, aggressive driving, and other factors possible are causes for this to happen. One thing is for certain, engines with this problem has sludge/dirt/carbon deposits around the adjusting unit that failed. So it may not be a bad idea to check this, on high mileage hard working M54 engines or any 6 cylinder engines with this intake system (_including M52TU_).


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## Fast Bob (Jun 4, 2004)

It`s hard to tell from the photo....is that pin pressed into the housing, or was it designed to be removable ? If the latter, could it be secured in place with some red Loc-Tite ? Do you see any practical way to prevent this from happening ?


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## BMW_tech (Sep 20, 2007)

Fast Bob said:


> It`s hard to tell from the photo....is that pin pressed into the housing, or was it designed to be removable ? If the latter, could it be secured in place with some red Loc-Tite ? Do you see any practical way to prevent this from happening ?


The pin appears to be pressed into the housing and is part of the "spring" mechanism that keeps the flap opened OR actuated closed. I have 2 faulty ones I kept, I will try to get a picture and upload it when I get a chance. There seems to be no practical way to prevent this from happening, at least not the way I can see from looking at the pin that fell out.

Forgive me but this is the best I can get with a camera phone.


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## FreeFlowBMW (Sep 25, 2008)

i notice an aggressive growl from the engine around 4k rpm's when going hard.... definitely the disa valve opening. I guess thats how I know mines working... or that its working in general.... I absolutely love that sound  my motor produces at this point

I also notice the car seems a little bit slower to get on power when going at it before that 4000 rpm boost.... its odd... I also have cams that come alive at about 4000 rpms

I'm wondering if some software could smooth out the transition?


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## Fast Bob (Jun 4, 2004)

FreeFlowBMW said:


> i notice an aggressive growl from the engine around 4k rpm's when going hard.... definitely the disa valve opening. I guess thats how I know mines working... or that its working in general.... I absolutely love that sound  my motor produces at this point
> 
> I also notice the car seems a little bit slower to get on power when going at it before that 4000 rpm boost.... its odd... I also have cams that come alive at about 4000 rpms
> 
> I'm wondering if some software could smooth out the transition?


Sounds like you have the classic "4,000 RPM Dip"....if you use the SEARCH function, you`ll find lots of references to this (rather common) problem. There was a service bulletin on this a couple of years back to get the control module re-flashed, it has to be removed & sent to NJ.


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## Fast Bob (Jun 4, 2004)

BMW_tech said:


> The pin appears to be pressed into the housing and is part of the "spring" mechanism that keeps the flap opened OR actuated closed. I have 2 faulty ones I kept, I will try to get a picture and upload it when I get a chance. There seems to be no practical way to prevent this from happening, at least not the way I can see from looking at the pin that fell out.
> 
> Forgive me but this is the best I can get with a camera phone.


Is that housing made from ABS (or other thermo-plastic) ? How about the possibility of fabricating a small cap to fit over that boss that the pin passes through, and epoxy or Loc-Tite that biotch in place ?


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## lild (Sep 11, 2007)

i have a 97 528, do i got it and exactly where is it?


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## BMW_tech (Sep 20, 2007)

Fast Bob said:


> Is that housing made from ABS (or other thermo-plastic) ? How about the possibility of fabricating a small cap to fit over that boss that the pin passes through, and epoxy or Loc-Tite that biotch in place ?


You always have the answers sir. I suppose that would be the ideal preventative measure. I knew if anyone here could come up with some type of solution, it would be you. I put it out here coz I happen to see 3 in 1 day and at least once a week. Perhaps it's the quality of our fuel regardless of grade. But what do I know? I'm just an underpaid tech.



lild said:


> i have a 97 528, do i got it and exactly where is it?


Nope. Yous don't gots it.


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## Fast Bob (Jun 4, 2004)

BMW_tech said:


> You always have the answers sir. I suppose that would be the ideal preventative measure. I knew if anyone here could come up with some type of solution, it would be you. I put it out here coz I happen to see 3 in 1 day and at least once a week. Perhaps it's the quality of our fuel regardless of grade. But what do I know? I'm just an underpaid tech..


Your input on these matters is greatly appreciated....the better informed we are, the better chance of survival we have.
On a slightly different matter, do you think it would be possible to replace the oil seperator with something a little less complicated (like a good old PCV valve)?


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## FreeFlowBMW (Sep 25, 2008)

Fast Bob said:


> Sounds like you have the classic "4,000 RPM Dip"....if you use the SEARCH function, you`ll find lots of references to this (rather common) problem. There was a service bulletin on this a couple of years back to get the control module re-flashed, it has to be removed & sent to NJ.


No sir, it isn't the power dip....

The "Power dip" creates a loss of power @ 4k, NOT a gain!!!!!!! I can hear the intake open up around 4100 rpm's... kinda like getting on boost in a turbo charged vehicle... just not as intense. Again, I have aftermarket cams that dyno a 13+hp gain at or above 4k.......... no hard feelings but read the entire post 

As far as the DISA, they rarely fail.... if you feel your car may have a failing unit you'll notice a loss of power, replace the dang thing!!


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## Fast Bob (Jun 4, 2004)

FreeFlowBMW said:


> No sir, it isn't the power dip....
> 
> The "Power dip" creates a loss of power @ 4k, NOT a gain!!!!!!! I can hear the intake open up around 4100 rpm's... kinda like getting on boost in a turbo charged vehicle... just not as intense. Again, I have aftermarket cams that dyno a 13+hp gain at or above 4k.......... no hard feelings but read the entire post
> 
> As far as the DISA, they rarely fail.... if you feel your car may have a failing unit you'll notice a loss of power, replace the dang thing!!


In your previous post, you stated:

"I also notice the car seems a little bit slower to get on power when going at it before that 4000 rpm boost.... its odd"

Sounds suspiciously like the 4K dip to me, that`s right where it occurs, and has been documented on numerous ZHP dyno sheets, where it`s *clearly* visible....


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## jimjackson (Oct 10, 2008)

*DISA flap problem*

My 530d recently died when the DISA flap on the 5th cylinder was sucked into the engine. Local BMW dealer looked into it and charged me over a grand for the privilige of telling me that it meant I needed a new engine costing £14,500.00 (yes that's not a typo - over fourteeen grand!!!).

Has this happened to anyone else? I'm clutching at straws hoping it's some kind of 'latent deffect' on the car and that there might be some avenue of recourse to BMW. It is a 5 year old car and has a full BMW service history.

It seems a rather bad design fault that something so small can lead to a new engine being required.

Any help or advise will be gratefully received.

Thanks.


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## ktc (Jan 10, 2005)

BMW_tech said:


> I am not sure if fuel quality, aggressive driving, and other factors possible are causes for this to happen. One thing is for certain, engines with this problem has sludge/dirt/carbon deposits around the adjusting unit that failed. So it may not be a bad idea to check this, on high mileage hard working M54 engines or any 6 cylinder engines with this intake system (_including M52TU_).


Hmmm.... I remember you took out my DISA and said it was gummed up with sludge too 

I certainly hope this is not the root cause of pin coming out... who doesn't have sludge after driving around a few years?


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## FreeFlowBMW (Sep 25, 2008)

ktc said:


> Hmmm.... I remember you took out my DISA and said it was gummed up with sludge too
> 
> I certainly hope this is not the root cause of pin coming out... who doesn't have sludge after driving around a few years?


I recently swapped out my cams... I noticed no sludge at all!!!!


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## Chris90 (Apr 7, 2003)

Will this fix my Vanos rattle?


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## FreeFlowBMW (Sep 25, 2008)

I had a wet dream where my rattle went away and my brain was able to focus on other things during that 2k-3k rpm range.... things like the birds chirping, leaves falling off the trees etc.... it was almost euphoric

My friends think it sounds like a high performance motor resonating..... EITHER way... me and you my friend are doomed! It shall haunt us drivers till the day ........ whatever day that is when we no longer hear a 2k-3k rattle!


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## FreeFlowBMW (Sep 25, 2008)

Ok so, back on topic..............

Is cleaning the DISA valve worthwhile?


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## BMW_tech (Sep 20, 2007)

ktc said:


> Hmmm.... I remember you took out my DISA and said it was gummed up with sludge too
> 
> I certainly hope this is not the root cause of pin coming out... who doesn't have sludge after driving around a few years?


Stop by when you have time. I will inspect it for you.


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## TerraPhantm (Nov 22, 2004)

The pin on my old DISA flap was loose, but when I looked inside, it didn't seem like the pin would have much room to completely come off. I did replace the unit anyways since it was making noises, but it didn't appear there's enough room in the manifold for the pin to drop out (except while removing the flap.) It did definitely move in and out, since it did have some paint scraping off of it indicating it was rubbing against something.


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## gtxragtop (Feb 25, 2008)

I see that at $210 + core one should not likely consider this as a PM part
ADJUSTER UNIT 1 11617544805	$210.92 +core


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