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Hiya, im getting some strange surging in engine acceleration and was wondering if my DISA flat could be playing up.

Its not making a noise and I can see the actuator move on the outside but I hear the flat can get loose on the spindle and stop working correctly, is there an easy way to find out perhaps?

Kind regards,

Adam.

Read this:

http://www.z4-forum.com/forum/viewtopic ... 30&t=12150

I had a faulty one that wouldn't stay closed. It 'rattled' in the closed position.

I just bought a new one for about £100 and fitted it as described.

No rattle since. I wasn't aware of the worn pin issue at the time.

Good luck.

Sceptre

I'm going to check mine out when I get my car back Have a long trip around europe planned and wish everything to be ship shape before I leave.

Thanks for the link shipkiller, can you kindly delete my post on the thread you linked to - that was a mistake on my part!

My symptom is that under partial throttle openings the engine can surge in torque ~ 3.2 krpm, I was wondering if the DISA could be playing up and losing low down torque to cause this.

Failing that maybe I have a dodgy coil pack or o2 sensor... ho hum...

I get a surge in torque also at about 3K. That's the Vanos doing its thing.. I love it...

Maybe i'm trying to fix something that doesn't need fixing then

Does yours only do it under light thottle when allowing the engine to pick up speed around 3k... on WOT I don't get it, only when tootling.

That I cannot answer without more research. I will let you know.

I have an annoying slightly metallic Buzz/Rattle from the Pax (UK) side that may be this. It occurred after i removed the 2nd piece of sound generator foam. It seems like a resonance that only occurs at certain rpm (1500-2500) under low throttle loading.

Could this be related? Id usually attribute it to rattling trim/panels/window regulator - but ive eliminated all these as best i can!

Ed, that sounds like exactly what I had.

DISA replaced under warranty.

Cheers Mattt! Warranty expired in March so I'll try giving it a clean around with carb cleaner when i get chance to see if that helps I always thought the engine 'ticked' a little too much!

This weekend I also had major part-throttle hesitation at 3000rpm, but i attributed that to the Throttle Pos Sensor or VANOS. Maybe this was the DISA also!

A little shocking from a car with 36k! But hey ho!

EdButler wrote:I have an annoying slightly metallic Buzz/Rattle from the Pax (UK) side that may be this. It occurred after i removed the 2nd piece of sound generator foam. It seems like a resonance that only occurs at certain rpm (1500-2500) under low throttle loading.

Could this be related? Id usually attribute it to rattling trim/panels/window regulator - but ive eliminated all these as best i can!

Yeah what Mattt said. Sounds just like a DISA valve worn. This is covered under most extended warranties too as it does control air coming into the engine.

I've never noticed throttle hesistation with mine (including after it was swapped). Mine was just worn a little causing a rattle though. I can't remember when it started, but I don't think it was much past 36k.

Adam D wrote:Hiya, im getting some strange surging in engine acceleration and was wondering if my DISA flat could be playing up.

Its not making a noise and I can see the actuator move on the outside but I hear the flat can get loose on the spindle and stop working correctly, is there an easy way to find out perhaps?

Kind regards,

Adam.

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Found this
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 "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 M54 engines or any 6 cylinder engines with this intake system (including M52TU).
Attached Thumbnails





Sterling Grey 3.0i
MR BLACK
Member

Update:

Whipped off my DISA today as per the guide (will post some hints/tips in the how to thread).

I have a 2003 3.0 Z4 with 39,600 miles on the clock, the DISA was actually in reasonable condtion however a few things needed attention....

http://s105.photobucket.com/albums/m216 ... Z4%20DISA/

As you can see its quite dirty and has built up dirt and oily residue over age, nothing major but a spring clean helped the flat operate smoothly (I used carb cleaner and a paintbrush to carefully dislodge the dirt, was quite stuck on and took a good ten minutes to do).

Once clean I could see that the browny/orange rubber seal which the flap presses against was begining to deteriorate and showed signs of wear. When closed the valve pushes against a thin rubber cushon which had a few nicks and tears in it, you could also see wear where the edges of the flap has been rubbing against the outside edges (good reason to clean the dirt off!).

There was no end to end play in the flap and the pin was fine and secure, there was a little bit of movement/backlash in the open position due to slackness in the spring. I'm unsure if this is normal or old age having not seen a new one to compare it with. I expect the spring weakens with age and this may onset damage to the pin supporting the flap (could flap about in the turbulent air flow like a flag and stress the mounting pin leading to more serious issues).

Would be nice to see other DISA's to build a picture of how their conditions vary with age.

In refitting a lightly lubricated the moving parts with PTFE based spray and dusted the rubber with a bit of autoglym vinyl and rubber. I also and also undertook a throttle adaption reset. So far the car is driving very nicely and is quite smooth, that may be more to to do with the throttle reset than the DISA as despite being dirty I doubt it would have had much affect on its operation.

I'll whip mine off tomorrow.

Mine makes a rattly noise during operation, but the pump is silent run on it's own, and the unit goes silent if unplugged at idle, so it's clearly when the flap is closed that it is rattling (a non-perfect seal/give in the spring meaning it's oscillating open and closed a tiny bit!?)

Will see what it's like and take pics. Gonna try get mine replaced under warranty because it's clearly not right and will eventually fail (my workmates is quiet as a bell in comparison)...

Dave

How do you do a throttle reset?