DIY: Repair DISA rattle

If your engine sounds like a diesel your DISA might be the problem. The DISA is a valve that regulates the amount of air that goes in the intake manifold.
To diagnose the problem, simply check if the rattle is gone when the DISA is disconnected. First, open the hood and listen to the engine running. Now turn off the car, disconnect the DISA and start the car again. If the rattle is gone, you know the DISA is causing it.
http://s12.photobucket.com/albums/a2...t=MOV02505.flv

People have suggested taking the DISA off completely and closing the hole with metal plank. Others suggest cutting off the flapping part of the DISA so that it never closes. The third option is to either replace the DISA or try to clean it.

Parts: CRC Throttle Body Cleaner - about $10

Procedure: Take the DISA off.

Once you have it out, take out the little plastic cap. You see the moving mechanism for the rod. Spray Throttle body and clean it. See picture bellow.




Move the flap to fully closed position. Using the little straw that came with the cleaner, spray throttle body cleaner inside the the hole the rod goes into. (circle on picture) Keep moving the flap so that the cleaner can reach everywhere.
Spray and clean the flap area. (Arrow on picture)




Also spray in the little air hole. Be careful not to get cleaner in your eyes because moving the flap will expel it of the air hole.



Reinstall the DISA and the rattle should be gone.

Many thanks to Solidjake, Myfirst330Ci, Brian McKinney and all other bimmerfest members.

Hey guys how is easy to remove DISA. I have read procedure, but is it easy to access there? how many hours?
Thanks

Originally Posted by phlfly

Hey guys how is easy to remove DISA. I have read procedure, but is it easy to access there? how many hours?
Thanks

Try 15 minutes, lol. Remove the intake by taking out the 2 bolts and the 3 pop rivets, remove the MAF section, get a ratchet with an extension and a T40 (I think) head and just take out the 2 bolts. Slip it out and put it back in.



OP, thank you for this write up.

If you have T40 driver, it will take you 15 - 30 min. I took the air filter box out by removing the two screws, no need to take the plastic piece near the fan, just slide it out. You have to disconnect the sensors and undo the screw that secures the MAF sensor to the lower intake elbow first obviously. Then there are two screws that hold the intake elbow to the lower intake "hose".
Finally you have the two T40 screws. Just make sure you have T40 (star) driver. I tried using hex key for 45 min, then put everything back together, went to the store and bought a set of star keys. Using the T40 key I got the screws down in 2 minutes.

So to summarize:

2 screws - 8mm I think
3 flaw head screws
2 T40 screws

Hey guys,

Thanks for DIY!
Quick question: the flap on my DISA moves freely for about 180 degrees. No resistance from stop to stop (from 0 to 180 deg). Is it how it should be?

Originally Posted by Nervous

Hey guys,

Thanks for DIY!
Quick question: the flap on my DISA moves freely for about 180 degrees. No resistance from stop to stop (from 0 to 180 deg). Is it how it should be?

Nope. There should be spring-loaded resistance to fully close the flap, in one direction. If not, I'd replace the DISA assembly itself.

I take it that since you have to remove the rubber air intake boots to get to the DISA and if they're old, cooked and brittle, there is a good chance of damage in the process, right? So it may be a good idea to have a replacement set on hand before starting, right?

Also, would a bad DISA or ICV cause failure to start?

Originally Posted by jcourcoul

I take it that since you have to remove the rubber air intake boots to get to the DISA and if they're old, cooked and brittle, there is a good chance of damage in the process, right? So it may be a good idea to have a replacement set on hand before starting, right?

my guess is yes

Also, would a bad DISA or ICV cause failure to start?

my guess, no... unless there is a huge vacuum leak where the disa goes. but a vac leak doesnt seem to be your prob.... seems more like fuel pump related

Originally Posted by marlin1881

Nope. There should be spring-loaded resistance to fully close the flap, in one direction. If not, I'd replace the DISA assembly itself.

Thank you, I see now: the flap is completely detached from the rod, there should be something that attaches one to another in the middle of the flap. And this part is missing on my DISA.... Oh, well, another $150.....

Originally Posted by Nervous

Thank you, I see now: the flap is completely detached from the rod, there should be something that attaches one to another in the middle of the flap. And this part is missing on my DISA.... Oh, well, another $150.....

We've seen a LOT of these fail over the years, and it honestly surprises me to the volume. This part is on the intake side of things, and really shouldn't be subject to as much heat as some other plastic parts under the hood. Most of these failures are related to the flap being broken somehow, or leaks around the gasket where it mates with the intake manifold.

It's an easy fix, but it ain't cheap.

To those who already know their DISA is malfunctioning, you might want to look at this thread to see why you don't want parts of it flying through your engine and taking out cylinder #3!

Good grief!

Betcha fixing that cost a wee bit more than a piddling new DISA!!

Originally Posted by jcourcoul

Good grief!

Betcha fixing that cost a wee bit more than a piddling new DISA!!

Yep, That is why I had the Indy replace the intake boot and DISA when they did the oil separator (CCV)!

Greg