2007 2.5i DISA Valve Check

[lucasxdiniz]

Hi, everyone.

I've watched videos and read loads of forum posts on DISA valves, what to check, how to check, etc. So as a bit of preventive maintenance when servicing my car I took the DISA valve out of the intake manifold (I only have one as I have a 2.5i). I first left it connected and checked for play and there was none (yay!), then I tried moving that flap to see if it would get stuck, then I realised it wouldn't move. I then disconnected it from the wiring and had a better look and I realised that it is not similar to the ones I've seen -- this one doesn't seem to use vacuum, so must be electronic only. Could someone watch the video below and tell me if I have a faulty valve?

I'm keen to learn more about these engines and the car in general so feel free to give me any tips.

https://youtu.be/RBjW7FYbVGw

[lucasxdiniz]

I decided to start the car with the DISA connected to see if it closed. It moved an insignificant amount. Is the motor buggered?

https://youtu.be/nFnR5OypzbE

[ph001]

You’ve probably worked out by now that your earlier research was probably on the M54 engine which has a different type of DISA to the N52. The latter do not tend to give many issues (they are driven electrically by a geared motor) but they should either be open or closed (not halfway between). If you read the N52 tech bible here... viewtopic.php?f=2&t=113354

...it shows a diagram of how they are connected. What it doesn’t say is at what rpm they flip over but I have a feeling you weren’t revving the engine high enough for them to change state.

[lucasxdiniz]

You’ve probably worked out by now that your earlier research was probably on the M54 engine which has a different type of DISA to the N52. The latter do not tend to give many issues (they are driven electrically by a geared motor) but they should either be open or closed (not halfway between). If you read the N52 tech bible here... viewtopic.php?f=2&t=113354

...it shows a diagram of how they are connected. What it doesn’t say is at what rpm they flip over but I have a feeling you weren’t revving the engine high enough for them to change state.

I was looking at DISA valves without looking at N52 ones specifically as I had assumed they were the same between different engines. I've managed to find a few videos of it now, but I still want a confirmation that mine's definitely buggered before I spend money on another one. I'm concerned because of what I read on a E90 forum (https://www.e90post.com/forums/showthread.php?t=1491906). The DISA seems to be very similar, if not the same, and it seems they are meant to close when the engine starts and open again at some point around 3-4krpm.

I've logged some data (engine RPM, DISA Position %) after assembling everything back together, if you feel like having a look:
https://1drv.ms/x/s!AoAAw4ET48j5gtN-sFsPteAwr5-IHQ

[lucasxdiniz]

Update for posterity:

A fully working DISA valve should definitely go from open to closed on start-up. So the videos above show a faulty DISA valve trying to close the flap. However, you shouldn't be able to move the flap with your hands, it is quite stiff. I checked this in two other Z4s now.

[ph001]

Thanks for the update. Good to know.