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The DISA is part of your intake system and allow better torque curves at various RPMs but when it fails it can be catastrophic to your engine.



Do I have your attention yet...

I ran across this post over on Bimmerfest by forum user BMWTech. http://www.bimmerfest.com/forums/showth ... p?t=317362

Here is the meat of the thread but you should read the entire thread.

"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 "dynamic" effect. For example, as the intake air is flowing into cylinder #1, the intake valves will close. This creates a "roadblock" 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 "wave", 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 engines"


This is for the M54 engine intake system (M52TU engine also), but it could be for other models also.


A couple of weeks ago, I ran a can of Seafoam through the intake system to clean it up. Every time I do this the engine runs better.
So after reading the post over on Bimmerfest, I decided to pull my DISA and inspect it.
Note: I did not have any symptoms of a failing DISA.

Here is what I found.

A picture of the DISA on the car:


Removal took about 10 minutes.

First remove or position the intake pipe out of the way. I loosened a lower clam on the intake pipe, then I just pull the MAF out of the filter box (still connected to the intake pipe) and rotated the assembly out of the way.

Then pull the electrical connector off the DISA (no. 1 one the picture), then remove the two torx bolts holding the assembly to the intake manifold.


Pull the DISA out.

The next set of pictures are of a dirty DISA. Like I said above, I cleaned the intake with Seafoam, but I do not have a pre-cleaning picture to compare.




Major deposits. These will keep the flap from closing completely and/or not allow the flap to move freely.


The outer pin which is the problem child of this assembly.


The DISA off the car:


After cleaning the flap assembly with carburetor/choke cleaner, here are the results:



Installation is just the reverse.

After seeing the inside of the intake manifold, I plan on another treatment of Seafoam to try to get the rest of the gunk out of the intake manifold.

I am not sure if there are any power gains I can feel, but I now know that my DISA is OK and a clean intake is a happy intake...

This is preventive maintenance. It's cheap, quick.

Remember, read the entire post over on Bimmerfest: http://www.bimmerfest.com/forums/showth ... p?t=317362

Wow Very helpful, didn't realise it was quite that easy to remove, I will check mine out before I go on my european road trip and post piccies of a 38k mile 2003 unit for comparison.

Thanks!

Also if some of ya'll have a rattle that stops after around 3400 RPM then it's probably this valve loose. Should be covered under most extended warranties as Shipkiller said it's important to the correct operation of the engine.

BTW it's a $240 part here in Vegas.

Mine makes a rattly noise, but I'm almost 100% sure it is the accumulator pump failing, not the actual flap rotating shaft.

Iirc, it runs on a 12v feed, so you can test it with the engine turned off to determine quiet operation of that part (which I should do to confirm)

Mine was a bit mucky, but clearly sealing nicely as confirmed by an almost perfect torque curve shape recorded with the cross-over points clearly noticeable.
Want to replace it, but it seems stupid to spend £100 to fix a £5 crappy vacuum pump. Why they didn't run it off the brake vacuum line (right next to it), and operate a solenoid is beyond me.

Dave

i wish i would have read this a few months back. would have saved me toooooons of money.

Great post! will be taking mine apart next week for preventive maintenance.

Updated my thread http://www.z4-forum.com/forum/viewtopic ... 44#p189801 with my findings and photos.

I gained access to the DISA bolts slightly differently by leaving the MAF conected to the airbox lid (mainly because it didn't want to come off!). At the point at which the hard pipe from the AFM joints the rubber trunking, undo and jubilee clip on the MAF side (there are two), until its loose but not so loose that it can fall off!

You should then be able to twist the pipe off and then flip the airbox lid over and out of the way to have full access to the lower DISA torx bolt.

Well worth doing this as part of a preventative maintaince program, takes 45 minutes max.

I took the DISA out on my 2006 3.0Si. My DISA was held in with four Torx screws. I found it easier to remove the top of the air filter box along with everything else. Once all of the black plastic intake plumbing is out of the way, you'll see to the rright of the DISA a metal bracket that holds two hoses. Remove the hoses (pull them up) and remove the bracket (two Torx screws) - then you'll have easier access to that lower right Torx screw on the DISA. It will also give you more room for your hands when pulling the DISA out. I had difficulty pulling the DISA unit out since the intake opening below it interferred. That intake opening has a black rubber/plastic collar held on with a screw clamp. I was unable to get it off. The collar had enough "give" to it that I could press down on that while pulling the DISA out.

My DISA was clean with 37,000 miles on the car. So I put it back in.

Getting the big black plastic intake back in and secure was not easy. The trouble spot is the lower connection facing the firewall. With one hand you want to support it underneath to make sure the connector is fully in and on its male fitting. You also want to shove the intake back. Make sure that ribbed connector is pushed back as far as possible and then tighten the clamp screw. I found the best solution to be setting the large central fitting in place first, then work with the rear fitting and then the air box up front.

Thanks very much for this guide. I took mine out and it was fine at 40,000 miles so a quick wipe with some 100% alcohol and it was ready to go back in.

well.. I'm at 64k miles, which i think is the highest on this thread so far...
I'll whip mine off on the weekend and take some before and after shots.

What's this "Seaspray" all about then?

sk93 wrote: What's this "Seaspray" all about then?

It's when you relieve yourself in the water at the beach.

I took my DISA out today for a look too - easy job as mentioned before, I managed it and I'm a desk jockey not a mechanic! I got the black plastic air intake out of the way by loosening the top and bottom metal brackets, gently pulling the top part out of the air filter box (after unclipping the two small metal clips), and then gently rotating the air intake round so the opening pointed upwards. 2 torx screws for me too (2003 2.5i).

Mine was mostly clean (not nearly as bad as the one in shipkiller's post), but the pin does have approx 1mm of play in its socket (side to side motion, not in and out). Mine makes exactly the same noise as Adam D's in his vid (a kind of thin metallic rattling). Currently I'm trying to resolve a ragged sounding engine, the dealer suggests it's the lifters after previously replacing a coil pack, but I want to troubleshoot anything else I can first (and the ticking is definitely from the disa area).

Had to reset the clock afterwards, but apart from that it was all good.

Can anyone confirm it won't throw an error code if I disconnect the electrical connector from the disa and switch the engine on? I know it's been mentioned that it's ok, but I want a bit of reassurance on that before I give it a go!

I did mine at the weekend. i took mine out to find that it seemed pretty clean ? i was expecting it to be fairly dirty given its a late 2003 model with 60k miles on the clock. The central pin had about 1mm of 'play' in it moving left to right, but otherwise seemed in good order and the pin seemed to be fixed solid and showed no signs of coming out.

I then unplugged it and found that there was no difference in engine noise, ie. no rattles. Once cleaned i put it back in and for soem reason the car does feel a little smoother under acceleration, marginal but i am a perfectionist and can notice it very slightly.

The question is then, do i need to replace it with the 1mm play on the pin ? as i said, it moves left & right and the pin feels very secure ?

thanks.

easty027 wrote:I did mine at the weekend. i took mine out to find that it seemed pretty clean ? i was expecting it to be fairly dirty given its a late 2003 model with 60k miles on the clock. The central pin had about 1mm of 'play' in it moving left to right, but otherwise seemed in good order and the pin seemed to be fixed solid and showed no signs of coming out.

I then unplugged it and found that there was no difference in engine noise, ie. no rattles. Once cleaned i put it back in and for soem reason the car does feel a little smoother under acceleration, marginal but i am a perfectionist and can notice it very slightly.

The question is then, do i need to replace it with the 1mm play on the pin ? as i said, it moves left & right and the pin feels very secure ?

thanks.

is there no way you can put a spacer in instead of buying one?

this is my job for the weekend

Just removed mine for maintenance. Surprisingly, it was quite clean and I was happy to see nothing was loose. Only needed a wipe and back in it went. The whole procedure took less than 20 mins. (2003 3.0L M54 with 45,000 miles of occasional summer drives only since new).

Thanks for this post, was of great help