[mebespencer]

Preface: 2006 330i, ~143k miles, 3IM from factory, some Dinan bits and other basic breathing mods.

So I recently got my hands on a Foxwell scanner and found the 2AAC code indicating a self-diagnosed DISA #2 issue (inboard side of the intake manifold). I cleared it, drove the car for a couple weeks, and sure enough it's back. At this point I was ready to write off that inner valve as busted and just go ahead and replace it.

Before putting in my FCP Euro order, I popped under the hood today and took a peek at DISA #1, to get some idea of whether it was on the way out too (it's never thrown any codes). The shaft was super tight and there was no discernable play, but with my Foxwell scan tool the 1st DISA would NOT activate. I mean it wouldn't even try, just the slightest thump of a stepper motor thinking of moving and then nothing. When testing DISA #2 (via ears, not visually yet) I could hear clean actuation, exactly like I'd expect from Youtube videos of people testing these.

This is where things get bizzare: the scan tool says both DISAs pass my manually-initiated tests. How could DISA 1 pass if it didn't budge by a single degree? Why would DISA 2 be throwing codes if it was the happy camper when asked to actually do something?

I'm probably just gonna go ahead and replace both of them, but I'd like to hear the input of some 3IM gurus before blowing 300 bucks. What do you guys think of this situation? Is it possible that my notions of "1" and "2" are just mixed up?

Lastly, folks who had busted DISAs that then remedied all of their intake issues: how does the torque/responsiveness of the car feel before and after? I've been feeling like my midrange has been lackluster for quite some time now, but I generally chocked it up to "I'm getting too used to flooring it" and "the car's getting old" (I'm on my 4th year of ownership). Maybe my IM has just been running semi-statically and has genuinely robbed me of some power?

Thanks in advance!!

[bluewater328]

That's why people lose power with the 330i and 3IM Converted ones and they dont even know. It wont always throw a code. Part of it too is what actually happens in there and IIRC William92 pointed out. For all that the car knows, the DISA servo was activated: The motor was powered to turn on, and it did. But the worm drive doesn't always mate up well (esp as it wears or if you bought the knock-offs), and in some cases the shaft disconnects. So since there are no further nannies to monitor whether the flap actually opened, it relies on the servo's report to the DME that it activated.

Now, you may still get a code based on fuel mix or rough idle starts that sort of leads back to the DISA. But there are a lot of dead or dying DISAs that dont throw codes.

You can test some of this when you take them both off by using the inner DISA on the outer DISA cable - like coil pack checks I guess. DME doesn't know the hardware difference and just reports whether it activated or not. They can be activated/tested with INPA as well.

My take is the inner one has shown its faulty. Replace. If you want to hold off on the outer, go ahead, as its only a few extra screws to access that one compared to the work to get to the inner one (when/if it fails).

[mebespencer]

Thanks for the quick response. Interesting how the leads are interchangeable - I might just use that to do a little more diagnosis. It makes sense that from the DME's point of view, a moving motor is all it can verify.

For the sake of getting lost power back and just keeping the car reliable, I'm just gonna buy both and replace them at once. I might report back in this thread if anything pops up, otherwise I'll be too busy driving the shit out of my car. Thanks again.

[bluewater328]

No prob. Do the test afterwards and tell us what you find. At one point I did the same as your planning and now if it ever goes again, its just getting shipped to FCP.

[mebespencer]

So I just got the new DISAs in, reset adaptations, and went for a short drive.

As far as testing the valves went: my Foxwell scan tool has an "activate" and "deactivate" button for both of the DISAs, and the original small DISA pulled out in a closed state (as I understand it, they're supposed to both be open when the car turns off). When I told it to activate, it went all the way open (taking much longer than it should, it was clearly struggling here and took multiple whirrs of the motor to get perpendicular), and then stayed that way. No further combination of "activate" or "deactivate" could get it to respond in any way -- just like the big valve that was never throwing codes.

When I hooked up the new valves (shipped in open position) the story was the same: maybe a nearly imperceptible thump from the stepper motor (perhaps verifying it's at an end stop) and then nothing. This leads me to believe that, at least within the limitations of my Chinese scan tool, this is actually expected behavior. Odd, that the testing will only do anything if the valve isn't in its fully open position, but I guess remotely reassuring that both of the new DISAs were behaving exactly the same.

I buttoned everything back up - the smaller DISA was a bitch because I pulled the alternator and snuck it through that opening, but aside from some interference with a PCV hose I was able to wiggle it in - and then went for a 15 minute drive. I took it easy for the first 5 minutes and kept it under 3k, and then when I felt the car was warm enough I started doing some pulls up to 5k. This is exactly how I remember the car. No dip in torque, just shoving you in your seat more and more and more until redline. A usable midrange makes ALL the difference, because I'm almost always finding myself between 3 and 5k when I just wanna have a bit of fun. Since it's been raining today, matting it in first got my traction light on before 4000 rpm - a clear indicator that there's a lot more torque than before because this would practically never happen previously.

All in all, very happy I caught this and sprung for the fix sooner rather than later. I can't wait to get back to west coast canyons in the summer (I'm a student in Illinois most of the year) and feel the extra torque there. The only thing that remains to be seen is the reliability of these Vaico branded replacements valves. FCP recommends them but customer reviews are not so hot as far as longevity goes. If I can get 50k out of these, I'll be a happy camper.

[E92_William]

That's interesting that the foxwell doesn't properly actuate these even the new ones, I thought it would have no issue doing so as I recall others testing them with it before. Inpa is always the best choice imo.
I'm sure there's tons of people with 330s, 530s, x3s, etc that have no idea they're leaving power on the table because their valves quit working or slowed down as the car aged and it throws no SES. I bet both of your valves were packed with old pcv oil, can probably hear it inside if you shake the small one lol.

[mebespencer]

Yeah, they were totally soaked. The loss of power definitely felt gradual, I can't say there was a single day where I thought to myself "my car is sluggish today". But back-to-back after the DISA fix, I could absolutely feel the difference.

I'm thinking of getting INPA as a more heavy duty solution when I need to do legit diagnostics or code stuff out, but for the time being I'm pretty happy with Foxwell considering I can keep it permanently in my car and get a good idea of what's happening if I ever break down on the side of the road.