TD5 VNT/VGT turbo compressor surge/waste gate flutter

[twr7cx]

I have a TurboTechnics VNT/VGT installed on my D2a TD5. In certain conditions I'm experiencing waste gate flutter/compressor surge (a 'wooo-too-too-too' noise when coming off the accelerator).
Commonly notice it when navigating long curved driveways - ie low speed and on and off accelerator driving, especially when reversing up a sloped one.

My understanding of this condition on petrol turbo charged vehicles is that it's caused when the throttle plate snaps shut and the air pressurised by the turbocharger has no we're to go - a blow off valve would then be used fro allow it to escape. But why would my TD5 which is dirsel with no throttle plate be experiencing this?

I don't believe that it does the turbo charger any favours so would be great if I could resolve it.

[harro]

No wastegate on the VNT.
Could be sticking vanes especially if it hasn't had a good run for a while.
If it is carbon build up get the turbo up to temp, and load it up (a bit of a flog[bigwhistle]) Might take a while in Tassie[smilebigeye]
This can burn off the excess carbon.

Have you touched the actuator rod or stop screw settings?


Paul.

[twr7cx]

Could be sticking vanes especially if it hasn't had a good run for a while.
If it is carbon build up get the turbo up to temp, and load it up (a bit of a flog[bigwhistle]) Might take a while in Tassie[smilebigeye]
This can burn off the excess carbon.

It's my daily driven vehicle although six weeks ago I changed work sites and now my morning commute is only 10 minutes instead of 30+ each way. Perhaps the shorter daily drive is having a side effect? But I did do a 800km round trip two weeks ago.

Was planning to head away this weekend so maybe a bit of work will set it back right...


Have you touched the actuator rod or stop screw settings?

No, my understanding was that they were factory preset and not to be adjusted so I've always left them alone.

[justinc]

Normal behsviour for a VNT when loading up andcoming off revs quickly. My l322 does it too if you stab the throttle when in gear maneuvering.

[twr7cx]

Normal behsviour for a VNT when loading up andcoming off revs quickly. My l322 does it too if you stab the throttle when in gear maneuvering.

Ah glad to hear. Funny that I only noticed the noise so loudly after I changed my airbox to turbo hose from the factory unit to a Roose Motorsport silicone hose last night.

https://www.aulro.com/afvb/images/imported/2017/07/88.jpg

[discorevy]

The ribs on the old intake hose will have dampened the noise a fair bit and if you have a snorkel you'll hear it easier as well , personally, I don't mind the sound, the disco should go well.