Rattling Noise from the DISA/Intake Manifold

[STR1CK]

Hey
Here a question for y'all. I have noise coming from my DISA/Intake Manifold. Has anybody else had this problem. It almost seems like the butterfly valve has broke off and is rattling in there. Thanks Chris

[Ed montocchio]

HI Chris,

I am having the same trouble with my 318i 2001 BMW. I took it into the shop and they replace the DISA unit. The car still has this rattle.

The idle is also not constant. If you watch the needle on the rev counter, it fluctuates up and down (very slightly - enough to annoy me!). I am sure this rattle is causing the problems with the idle as the machines at BMW are not picking up any errors.

Did you ever get this fix -if so, what was the fix?

Look forward to hearing from you.

Ed

[Ed montocchio]

Hi,

The car is going to the shop again tomorrow. Hopefully they will find the fault.

Ed

[Ed montocchio]

It was the DISA unit. I thought I would add some info I found from another site. It is part number 6 on the attached diagram.

DISA is the german abbreviation for 'Differentiated Intake System' (Differenzierte Sauganlage).

Basically it is a valve that varies the effective length of the induction system depending on the engine speed, load and ignition switch position to obtain an improved torque over a wide speed range.

On the differentiated intake system there is a connecting valve between the intake pipes. This is closed when the engine is turning at low speeds to create high torque due to the long intake distance. When the engine is turning faster the valve opens - to produce a short intake distance and therefore more torque and power.

When the length of the intake pipe has been adjusted to the engine speed, a "reboosting effect" is created by the vibrating air column before the inlet valve closes. This optimizes the torque in both the lower and the upper engine speed range.

When the engine is turning slowly it provides a long intake distance and when it is turning faster it switches to the shorter intake distance. This means high torque and high power at all times.

See attached diagram (part # 6).

[dodj]

Hey i have the same problem, slight fluctuation in the idle. and i hear a clicking noise.

so is it the DISA valve is broken and is rattling around?

is it expensive to fix?

[Ed montocchio]

My car is still under warrantee so it was done for free. However, I know the part (DISA Flap) cost R1056 or $165 (if you can just use the exchange rate from SA??). You will also have to buy the gasket.

The labour cannot be very much as all you need to do is remove the 3 screws holding the unit and pull it out (no dismantling of the intake system). Remember to remove the plug under the unit (reach under the unit, press the clip, and pull the plug down).

I have read on some sites that some people have removed the unit and blanked it off with a cover and others have taken the unit out, cut off the flap and reinstalled the housing. (Not something I would do under warrantee). Without the unit you may feel a flat spot at around 4000 rpm as this is when this unit balances the intake.

Interesting, I found the noise because of slight fluctuations in the idle - but replacing the unit did not fix the idle - it did fix the rattle!!

I cannot find what is causing the slight fluctuations in idle - I will open a new thread for this topic.