Setup turbos that don't have a stop screw

[Pete737373]

How can you set up the actuator travel for the turbo if you have one of the models that don't have a stop screw? I've read the manual scans uploaded by @Crasher some time ago but it says to move the vane lever to against the stop screw. But some of these turbos don't have a stop screw and I have one of those. I've removed the intake part of the turbo, and the actuator, and now need to refit them, but I can't set the actuator position exactly since there are no witness marks (new core). Is there a procedure for these types of turbos or is it down to the factory to set the whole thing as a unit and ship it ready to use only?

Reason I ask is because having put it all back together theres a strange noise from the engine (turbo I think) after blipping the throttle. On the run down (once my foot is off the pedal, but the revs are still above idle and coasting down), theres a sound thats not right - maybe engine working against vanes that are too closed I suspect. If I take the vacuum pipe off the turbo actuator all is fine and it sounds sweet. This is on a 2011 2.0 TDI.

[Crasher]

If it is a vacuum actuator with electronic feedback these are set up using the measuring blocks display with a diagnostic system and a hand held vacuum pump.

[mickeybo]

engine code or reg number would certainly help

[Pete737373]

Thanks for reply and sorry I didn't realise anyone had replied to me - need to adjust my settings to email me.

It is the electronic one with an electrical connector on top - I understand re the feedback control aspect, and using measuring blocks etc. I think I read a post you made some time ago Crasher where you uploaded 8 images from a manual (which one I don't know but I read it carefully). That one mentions using the 'stop' to limit the downward travel of the actuator screw (IE how far it will go with increasing vacuum - at what point increasing vacuum will not lower the rod any further).

The procedure seems to require you to use this 'stop' point as a reference (IIRC around 0.7V as seen through the measuring blocks). But I don't have that stop.

I've adjusted it a bit and stopped the 'funny sound' by raising the nuts on the actuator rod (so the actuator lever is now higher - it does not close the vanes as much when max vacuum is applied). That sounds better now at least. So the vanes must have been shutting too far previously because the actuator was basically pushing the lever too far down. I guess software could also stop this happening by reducing the maximum vacuum applied to the actuator.

But still I am missing a part of the turbo that the adjustment procedure seems to need so I don't know how to get it exactly adjusted. I read about graphing target boost pressure vs actual boost pressure while driving - I wonder if I should use that? Seems more difficult to do this though because you need to drive I think.

TIA, Pete

[Pete737373]

Engine code is CFFB and its a 2011 alhambra but I don't remember the full plate at the mo. I can add it later when I see the car again if its useful.

Of interest, I read a few posts on here from previous threads about similar cars (not sure if they were exactly the same) but regarding the SCR. Yesterday I used a bore camera to take a look at the SCR and it seems damaged, but the car is not throwing any codes about this. I can see a chunk of what looks like SCR maybe 1-2cm thick on its side in the first chamber, but then after that there is a mostly intact looking SCR block with the holes looking perfectly open. My car has 2 chambers, I don't know if these are both SCR or 2 different things (this is all downstream of the typical VW DOC/DPF unit). Then much further towards the car rear there is a silencer box. Can anyone say what the 2 SCR looking boxes do - are they both SCR or different things?

I connected a powerful vacuum cleaner (in blow mode) to the input of the first SCR and checked the flow - its perfectly able to flow the cleaners full flow with virtually no flow restriction so its not blocked at all (this is from SCR to tailpipe). So the urea crystals problem is not present I hope. Whether the SCR was smashed by a previous owner and coded out though I do wonder.