Adjusting the wastegate on an Audi S3 1.8T (SOLVED)

Hello everyone.

"On an Audi S3 8L with engine code AMK and 210 horsepower, the diaphragm of the wastegate actuator has failed. My friend, who owns the car, was able to purchase a new, original replacement. My question is: how do I properly adjust the preload of the actuator?"
On the protruding rod, there is an approximately 100mm long M6 thread with two hexagonal nuts (size 10). The same applies to the rod on the old can. Between these two nuts, the linkage for the wastegate lever is fixed.

Should I now set the same distance between the dosing side and the nozzle on the new one as well?

I don't actually find that very plausible, because I can't really check or compare the spring force that keeps the flap closed in its resting state.

- Or should I adjust the entire system using a T-fitting and a pressure gauge installed in the control line of the can?

There should actually be a certain "base pressure," for example, 0.4-0.5 bar for the emergency mode, where the N75 valve switches off without power and a relatively low, pre-set boost pressure is regulated solely by the spring force within the actuator.
Perhaps the exhaust pressure, which pushes against the wastegate valve and causes it to open, also plays a role, or is this something that can be disregarded?

Best regards,
Mpire

Quote:

- soll ich nun den gleichen Abstand der dosenseitigen Mutter auch bei der neuen einstellen?

What's the problem if it's exactly the same part, one-to-one?

If you only mounted the old container occasionally, would you adjust its position or leave it in its original position?

Autoservice wrote:

What's the problem if it is exactly 1:1 the same part? Wenn du die alte Dose nur ab und an montiert hättest, würdest du sie verstellen oder wieder in ursprünglicher Position einstellen, bzw. belassen?

Of course, I wouldn't adjust the old can; it fit perfectly before .
Yes, it's the exact same can, from the same supplier and manufacturer, but it's new.
There's an 11-year difference, so is it possible that the shuttlecock had a different constant or tolerance back then?
I'm not sure to what extent the MSG (presumably a control unit or module) can relearn or adapt the required duty cycle of the N75 (likely a valve or component) in order to achieve a specific boost pressure, or conversely, avoid "falling out" of its operating range.
The entire control system is supposedly quite sensitive in the S3. Accessing the two nuts for adjustment can only be achieved by removing a lot of components and after a long cooling period. Ideally, I want to achieve the optimum setting on the first attempt so that I don't have to adjust it again .

Best regards,
Mpire

If you want to know the exact details, you need to talk to the manufacturer of the turbocharger. They will likely try to sell you a new one.

In the vehicle's onboard diagnostics (OBD) system, there is no information about this – except in cases of a defect where the turbocharger needs to be replaced .

I would replicate the setup exactly and observe/measure the results. If necessary, I would make adjustments.

According to my information, you have no other choice.

Okay, we'll tackle this over the weekend. We'll take out the old unit, measure it, and install a new one. I'll report back on how it goes. Yes, the dealer just wanted to sell us a new charger for €1427 plus VAT.
Thank you in advance for your support .


Regards,
Mpire

Hello.

Okay, the actuator has been replaced. The position of the nuts on the actuation rod was transferred from the old actuator. The system is now working perfectly again, without any jerking or similar issues.

Regards,
Mpire

Thank you for the feedback .

Did you also check the turbocharger pressure?

Autoservice wrote:

Thank you for the feedback. Auch den Ladedruck überprüft?

Yes, logically .
Maximum overboost approximately 1.2-1.3 bar, linearly decreasing to a holding pressure of 1.0 bar at approximately 6,500 RPM, which is within the tolerance range according to VCDS.



Regards,
Mpire