Torn wastegate membrane theory?

[A80Avant]

The dvs are Apr R1. They have a membrane not a piston, and are hard to dismantle to check. I'll get on it and report back.

Dawn the day is small and there is no light to work on the car....!

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[A80Avant]

I think the diagnosis is made...

My shop who rebuilt my wastegate did not take care of proper clearances.

Now the valve gets stuck on the guide and cannot move freely anymore, thus sometimes catching and staying open...

i dont want to risk RE-RE building this wastegate so i am now officially looking for a used one.

[Rusty]

This reminds me of when Newsh had boost creep due to having a 30mm WG on his car, instead of a 34mm.

There was a WG for £30 from a car that was being broken in the for sale section

[prj]

Yup, would have been my first guess, except that I remember you mentioned in a previous thread that you had that rebuilt...
Otherwise your symptoms were exactly that of a half-way stuck wastegate.
That way at start the gap is big enough for the gases to escape, so no boost is generated and towards the end more and more gases get fed through the turbo.

Kinda like a VTG stuck on the largest setting.

But I guess it is hard to suspect a freshly rebuilt wastegate...

[A80Avant]

yes, you put some trust in people's experteese, but it looks like i have given more credit to some shops than they deserve....

anyway, i found a replacement so hopefully in a few days the game is on in readjusting the boost settings and getting some decent power!

[EspenW]

Was it boosting properly when on the dyno?

[A80Avant]

No.
It had many oscillations on the introduction of high boost. At 1.4bar it was ok. But anything above that it caused strong oscillations and when looking at the logs you could see the N75 DC going up and down in opposite directions to try and settle things down.

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[newsh]

This reminds me of when Newsh had boost creep due to having a 30mm WG on his car, instead of a 34mm.

Yes it does me too.