Symptoms of a faulty DISA flap?

[Mr Whippy]

The free movement worries me more

The 1st animation shows the pin moving, but clearly something in the 'big end' is allowing this door to move about rather freely, and as such is introducing the ability for it to resonate back and forth a hundreds of times a minute, and I guess that is what is then allowing the shaft/pin bearings or whatever it uses, to wear too quickly.

In my case, the door can turn, even with the crank push-rod held fully deflected either 'open' or 'closed', by the amount shown in the picture (1st anim)... it's not even going to seal properly when shut, and will probably flap around loads as shown when open too.

I'd say that a new one doesn't do that, and if your flap is that wobbly without any crank end movement, it's ready to be replaced.

I'll report back on my 'new version' findings for others info!

Cheers

Dave

 

[Shipkiller]

Mine was rock steady. No movement at all.

Did not detect any binding at all when I had mine out.

 

[Adam D]

My pin was solid, no rocking as shown above nor did it protrude. (excellent videos by the way, very powerful in explaining the symptoms ).

It did however have the some looseness and play in the flap rotating ~ 5mm in the open position before the spring tension kicked in. It wasn't very loose but easily moved by hand.

 

[Aebous]

It should be under warrenty. If mine can get replaced for a rattle noise (it was on one of the external bits) with Maxcare warranty service, then BMW can for sure change it under warranty. Remember it controls airflow into the engine....very important for proper function and a very basic explanation.

 

[MR BLACK]

Mine was a bit like that when i took it out for inspection can't be great for controlling the air flow correctly,i rang Bmw they said they are not big sellers and the mechanic said the rattling is quite common i think they were around the £80 mark .
Great pics how did you do that

 

[cj10jeeper]

Now here's an interesting result.

Removed the DISA a couple of days back cleaned it, tightened the rivet and replaced it. Today I took her for the first proper run since and the response is dramatically different.

OK so placebo effect - I check and clean a part and assume it will be better, but it's not the case. I know the car too well and at around 1500 rpm in a high gear the slightest press of the throttle and you can feel it push forward with much more torque than before. Even MrsCJ commented that something was different and she did not know I'd tinkered. Perhaps it's sealing better now cleaned and tightened and improving low end torque. I'm open minded on these things but something changed

Downside is I've induced a new whistle. Almost like a squeak as the engine goes above and below around 1500 rpm. something else to fix :thumbsdown:

 

[Shipkiller]

Crack in your intake hose?

 

[cj10jeeper]

Crack in your intake hose?

Likely, or did not seat something correctly when refitted the valve

 

[Shipkiller]

Jeep,,

I too noticed a nice low rpm power increase.. Not a lot but noticeable. And I now really notice when the VANOS kicks in at about 3K...

I did not say anything for the same reasons as you. :roll:

 

[cj10jeeper]

Reassuring Ship when both of us experience similar things and knowing our cars inside out

 

[Aebous]

I didn't notice a difference after the DISA was replaced. Of course I was really tired so probably not paying attention.

 

[cj10jeeper]

Hey Shipkiller - no suprise - I found that one of the flexis after the airbox had not seated properly. Redid it correclty and the whistle vanished.

Teach me not to do things quickly in fading light (or at least put the floodlights on in the garage)

 

[Mr Whippy]

I think I'm off to buy this part tomorrow, or at least order it.

In the name of testing (because I think it will make some difference), I'll do an acceleration test in 3rd through the revs side by side with old vs new (swap during test)

Lets see how more filled in the torque becomes

Before fyi:

 

[Mr Whippy]

Ooof, £114 for a new DISA flap thingy from BMW.

Picking it up on Wednesday along with my new brake vacuum pipe (£21), the old one had collapsed... so a few little jobs to do

Really looking forward to seeing how secure it is. The parts guy went "ahh (knowingly), one of those" when I told him I wanted a new DISA flap actuator, so clearly they get a few with issues!

Dave

 

[Mr Whippy]

Just got my new one today.

Solid as a rock in every way my old one wasn't.

No give in the door in the open or closed positions when holding the crank arm in place, no lateral or longitudinal movement about the pin. I'll have to see what it is like after it's first month in place.

Will try do the before/after test this evening

Cheers

Dave

 

[EdButler]

Bump!

Any developments on this Mr. Whippy??

 

[Mr Whippy]

I haven't undertaken any empirical testing, but purely on perception the engine feels less confused at part throttle openings. The solidness of instant output that is clear at higher throttle inputs seems to be more apparent now at smaller ones, quicker.
The rattle is totally gone now too, much quieter inside and out at idle and when on the move (was surprising how loud it was!)

If it's rattling I'd say it's due a swap, and it's easy to tell at idle if it's rattling by simply unplugging it. It can't be good to have it rattling around as much as it does inside there. Fatigue will finally catch up with components and do damage, and fatigue wear must be off the scale with it rattling around as much and as fast as it clearly was!

Dave

 

[nadaclue]

Thank you, thank you, thank you!

This rattling/clicking noise has been progressively getting worse and noisier over the past 2 weeks and has started to make me paranoid. Today I did an oil change followed by an Italian tune-up but it was still there. Seemed to be located closer to the intake manifold than the head, almost sounded like extremely loud and poorly timed injectors so I started searching for common injector issues on the M54 but couldn't find much. So I started going through the "problems" forum hear, and found this thread. The part that made me really suspicious it was the DISA was the fact that the noise went away at higher RPM's. I just figured at the time it was being drowned out by the increased engine noise.

I went out to the garage, started the Z4 and was greeted by the incessant "ticking". Unplugged the DISA and holy crap it went away!

So again, thank you everybody. Saved me a trip to the shop and I can rest in peace knowing is a relatively inexpensive item and not my head or injectors.

Now the question is, can I drive it with the DISA unplugged for the next couple of days until I get a new one?

For the record, 2003 Z4 w/ 42k miles.

 

[Andrew D]

Can anyone post the part number for the replacement flap assembly?

I note on RealOEM.com that there are two entries for this item, one (part number 11617502275) ended 04/2004 and another still current (11617544805). Maybe a part redesign on the sly?