Intermittent shudder/vibration when releasing throttle

[chettaz]

Hi everyone,
I have a stock 2010 d40 ST (auto) which I have only had a few months and have recently noticed a shudder when I take my foot completely off the accelerator, it's intermittent and mostly occurs at slow speeds, but has happened a couple of times at higher speeds and doesn't matter what gear.

While in the video, it kinda sounds like blow-off, but I am certain that it's not, and it never shifted out of first gear.
The first one (5secs) happened when completely take foot off accelerator at 10km/h, the second one was at about 15km/h, I just held it longer.

Any ideas of what it could be?
Thanks

 

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had a car which would shudder and run rough at certain revs , was broken engine mount, could never figure that one out

 

[tweak'e]

that sounds a lot like turbo bark/flutter.
common cause is blocked up air filter.
also check turbo vanes are moving ie "wastegate" arm is moving. common for turbo control valves to fail.

 

[chettaz]

that sounds a lot like turbo bark/flutter.
common cause is blocked up air filter.
also check turbo vanes are moving ie "wastegate" arm is moving. common for turbo control valves to fail.

Thanks mate, that's a start. I'll check them out. This is the first car I've owned that's had a turbo so I didn't really know where to begin trying to diagnose it.

 

[chettaz]

that sounds a lot like turbo bark/flutter.
common cause is blocked up air filter.
also check turbo vanes are moving ie "wastegate" arm is moving. common for turbo control valves to fail.

I replaced the air filter and i think it resolved the issue, though I thought I heard the noise very faintly again a couple of days ago, but i thought I was just hearing things, as it was just a once off. However, today the turbo blew on me, so not sure if its related to that noise or not though..

 

[tweak'e]

turbo bark destroys turbo's.
basically its the compressed air going back through the turbo, typically because there is a large vacuum on the inlet side. it tries to make the turbo run in reverse.

 

[chettaz]

Cheers for the advice. I'll test for vacuum leaks when I replace it. Could this also cause poor fuel economy?

 

[tweak'e]

Could this also cause poor fuel economy?

o yeah.