2.5T Turbo blowing back into airbox - loss of power - no smoke

[justincase13]

The other day I was sitting in a traffic jam on a warm day for approx 30min.
Once the highway opened up I did what any normal person with a Turbo car would do, floored it.
Nothing crazy just a normal highway run up to approx 150KM/hr 5000rpm etc.
Then suddenly I hear a huge sound of air rushing/wooshing from the engine bay and lost a ton of power.

The car still drove ok, no smoke, but a huge loss of power and poor acceleration.
When driving it literally sounds like air is blasting from the engine bay.
I checked all intercooler piping and inlet pipe for cracks but all looks good.

I finally identified the huge air rush sound coming from the turbo area.
Visual inspection is good, no cracks, no leaks, and everything is dry other than a little oil around the turbo inlet clamp.

I opened up the airbox and had someone rev the engine with the brakes on to simulate some load and a large amount of air was blowing OUT of the turbo inlet pipe back into the air box. When driving it literally sounds like air is blasting from the engine bay.

I was initially thinking waste gate issue but VIDA is showing no codes and I can see the turbo control valve working.
My gut feeling is something is wrong with the turbo perhaps the impeller shaft broke? but there is no noise coming from the turbo at all.

I've attached a screenshot of some of the graphing I did with VIDA yesterday afternoon.

Has anyone else experienced these symptoms? Any ideas would greatly be appreciated.

The car is a 05 V70 2.5T

Thanks for reading.

[jonesg]

I would say the wastegate is stuck.
Disconnect the actuator pushrod , see if you can open and close wastegate arm.

[justincase13]

Tested waste gate today. Working fine and holding vacuum.

[vtl]

CBV is also a spring-loaded silicone diaphragm. It is responsible for pressure relief in a purely mechanical way, w/o external control. The blow-off air goes into intake, before the impeller shaft.

Here it is removed. PIA, but doable.

[justincase13]

CBV is also a spring-loaded silicone diaphragm. It is responsible for pressure relief in a purely mechanical way, w/o external control. The blow-off air goes into intake, before the impeller shaft.

Here it is removed. PIA, but doable.

I just tested the CBV today with a hand-held vacuum pump without removing it from the turbo. It held a vacuum for a while with no issue.
The wastegate actuator was tested with compressed air and it too held just fine with approx 30psi
I check the shaft of the turbo and inspected the exhaust side with a camera using a mini inspection camera all looks good, the bearing felt nice and tight; it spun smoothly in unison with the exhaust side.

No cracks in airbox or charge pipe.

No codes in VIDA other than my ABS light...

Would a cracked inter cooler do this?

Compression is good

Plugs look good

Bad Turbocharger Boost Solenoid maybe? but VIDA says otherwise...

I'm thinking of buying a boot leak kit at this point.

[jonesg]

I would look at the boost solenoid.

[justincase13]

I would look at the boost solenoid.

just tested it a moment ago.

Applied vacuum to the silver port, thumb on side port pointing up.

While holding 10psi I applied 12v in a few steps, you can see the vacuum drop with each application of 12v bursts (simulating PWM)

I assume this means the solenoid is good, audible clicks while I modulate 12v too.

Also checked resistance, sitting at 23.5ohms (within oem spec afik)

[scot850]

Check all your rubber hoses from the turbo to intercooler and intercooler to throttle body to see if any have come loose or possibly split. Checking for splits you really need to look carefully, or even remove the pipes to be able to see they are sound. Worst case is the intercooler has cracked but not heard of that as an issue.

Neil.

[jonesg]

Tested waste gate today. Working fine and holding vacuum.

but maybe not working on command, you have zero duty cycle on the TCV.
TCV tested good but what about the signal.

When its blowing air from the intake box, try reaching in and pushing the rod that opens the wastegate by hand.