If the vanes are sticking, they are in the exhaust route.
How can they be cleaned without taking turbo off??
Some cleaners say to spray into air intake. Can't see how that would work??
@andyfreelandy - the variable vanes are on the inlet side of the turbo. BUT the vanes are also in the exhaust route when the EGR is open. And therein lies the problem perhaps. The EGR opens when the exhaust gas pressure is exceeding inlet manifold pressure at partial load operation (that is it should not open at higher engine speeds under high turbo pressures).
So if I understand you, there are two questions. Cleaning and the signs and symptoms you mentioned (on a client vehicle?). For cleaning, turbo sprays are administered at low engine speed (2000rpm) when the turbo is
supposed to be recirculating gases via the EGR into the vanes of the turbo. So by spraying then, you get the solvent chemical action cleaning the vanes with the added benefit of high temperature gases aiding the chemical activities. But I cannot see that the exhaust side pressures and flow directions will ever draw a cleaner into motive side of a turbo. So you are right, those vanes can only be cleaned by stripping the turbo. I personally think that such cleaners would need to be applied regularly; they'll never clean a badly clogged, vane coated turbo as if by miracle. But equally for a client who wants his car back for Xmas at lowest cost, you're being asked to qualify for beatification!
This is why I retired, customer expectation is rarely balanced and reasonable.
On the engine performance question; on a non-variable vane turbo, the performance of the induction pressure is limited by the waste gate on the exhaust side opening, limiting engine damage potential. But with a variable vane turbo, the low end engine speed
emissions performance is changed by opening the EGR. The EGR should be closed under high turbo speed operation, for example going up a hill under higher engine load. If the EGR is blocked off, it cannot leak. But the lower end performance is modified in such instance (but blocking EGR's for most is about emissions though most don't realise it, it's fashionable behaviour). If the EGR leaks at higher engine speeds, then the gas pressures (and mass air flow rate) around the system will be much different that the ECU expects at the various monitoring points and then cleverly limits engine power via pump to prevent damage but at the same time ****es us off with a loss of power when we need it, towing up a hill? And a low line pressure and reduced flow perhaps?
Is the EGR connected? Is it end of life and the valve sticking open in a non-predictable way? I like EGR's myself. But they need to be clean and in an operable, reliable condition at all engine speeds.
So, to become a saint and quickly discover the "failure mode" of your customer vehicle, I'd blank the EGR and high load test it. If that doesn't work or you've inspected the EGR condition and operation, then I would agree, you need live data on the pump. I'm on my own too and appreciate how you feel about some jobs and their difficulty. Let alone customer expectation and the personal stress it brings. You'll be richer for this experience.
Or grey like me knowing alcohol should not be consumed in small quantities at critical relaxation times.
This link may help your client understand turbo's and with your explanation why a cleaner MIGHT work but isn't guaranteed:
