Or something else? This mostly happens when starting the car and the driop in boost pressure is accompanied by the dreaded "ENGINE SYSTEM FAULT"

Click image to enlarge

Have you checked the actuator to see if it is sticking? a common problem with them

Yes, checked and lubricated some time ago. Didnt seem to be stuck in any way but it's definitely getting worse. Got - 2017 SDV8 Autobiography in Loire Blue
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could be a faulty boost pressure sensor? Definitely seems to drop out rather than decrease slowly. There is nothing that can't be fixed with a hammer😜😜
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^ Is that something that can be replaced on its own?
I should also add that the EGR pressure is the same on both banks, so I hope that rules them out. Got - 2017 SDV8 Autobiography in Loire Blue
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You have either 1 actuator seized, a wiring issue to the actuator, or a faulty actuator

Unfortunately, the L/H turbo is a complete to get at, to check anything...

Thanks Mikey, is this showing at the LH turbo? When the Indy checked it, they said it was the RH (o/s) that was flagging an error? Got - 2017 SDV8 Autobiography in Loire Blue
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It is the R/H

Wooly head syndrome is in full effect. So used to it always being the L/H one at fault

Anyway, that makes things easier. I have seen the wiring fall out of the connector, causing the turbo to give 1 reading, and one reading only, and not move at all. Check that first

Does the actuator try and move through its full sweep? Someone switching the ignition on and off while you are underneath may help

Phew! That's a relief.
The actuator was moving freely and did go through a "full sweep" when the car was switched off and on. Would the position of the actuator change when the boost pressure drops like this?
How much resistance should there be in the actuator when the car's switched off? Should it be totally free of any resistance? It moved but it needed some effort to move it up and down but it certainly wasn't stuck. Got - 2017 SDV8 Autobiography in Loire Blue
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You are not measuring boost pressure in those graphs, that is only the actuator position of both turbos.

They should both move freely, with little, to no resistance with the ignition off. With the ignition on, they will be fairly stiff, but should always return to its "rest" position

Bear in mind, that even though they have been freed off, they do have a tendency to stick shortly afterwards, and may require another session of lubrication and moving them up and down

Thanks Mikey, I do have the actuator repair kit, which is essentially a new actuator arm. Would it be worth doing this before considering the whole turbo! Got - 2017 SDV8 Autobiography in Loire Blue
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I can't picture the turbo ATM. No idea what access is like.

I'd still be lubing and freeing it off. If it cures your issue, then look into fitting the repair kit as a long term fix

Interestingly enough, drove to Liverpool and the problem seems to have disappeared!

maybe it just needed a long run............  Got - 2017 SDV8 Autobiography in Loire Blue
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was probably just the inlet tract clogged up with soot/oil sludge.

Can't beat the old Italian tune up!  Got - 2017 SDV8 Autobiography in Loire Blue
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