Paulyy

it might be the cause. replace it and see what happens! good luck

CyCloNe!

Plug up both lines and drive it see what she does. You don't need the ISV to run the car, just feather the pedal till it warms up. That way you know for sure before spending money.

doabarrelroll

I got a hold of an extra ICV, replaced it, pressure tested the system, no hissing at all.

Anyways, no dice on a fix yet, still not boosting. I could barely tell the difference (if at all) with the new valve. I get blue smoke from the rear when getting into higher RPMs and the sound from the turbo is getting louder than before, I can really get a good ear of it with my head out the window.

Continuing to sleuth this out...

Paulyy

You've got a serious problem here.

Can you explain what happend before this happend?

Tedro951

The loud bang (if simultaneous) with boost loss should make this advice worthless, but nothing else seems to be working....

If it were mine, I'd do a compression test (either cranking or differential) and check the timing. If that checks out, I might temporarily install a loaner DME.

This may not make perfect sense, but 6 pages of thread haven't fixed it, either...

doabarrelroll

I've checked the timing and it is right on. I'll get a compression tester and check it out.

doabarrelroll

So, I'm in third gear at WOT (I imagine this is how a lot of broken car stories begin), anyways, I hit around 6k RPM and I hear a bang. The engine still running normally, I think it was a crazy backfire or something. I then realize it came from under the hood. As I pull away from a stop, the boost has vanished.

I've experienced the disconnected intercooler hose problem before too because the car won't even run, let alone start.

Ever since then, regardless of changes I've made to different parts of the car as described in this thread, no changes have been evident to me.

carlege

Do you know if the front of the turbo is spinning. Maybe you had a perfect break and the Exhaust is disconnected from the Compressor side.

doabarrelroll

Last time I pulled the turbo, I spun the exhaust and the compressor side spun with it.

Is there a problem that people experience with turbos that wouldn't be visible from an outer inspection that might cause this? Turbo failure that isn't known until disassembled?

doabarrelroll

Anyone ever have an issue where their turbo wasn't receiving enough oil? Journal bearing turbos need oil to spin normally.

Paulyy

take the IC pipe off coming from the turbo while the engine is running and see if theres any air being pushed by the turbo.

TurboTommy

When your system is under pressure the bypass valve should never open. When the engine is running the pre-throttle pressure is always higher and if this valve is no good, you won't make any boost; not even the 0.5 bar.
I didn't read everything carefully, here, but did you actually take the valve off and bench test it.

Also, if the car engine isn't running overly rich at full throttle, there won't be any significant intake leaks, except this recirculation valve.

doabarrelroll

When I benched tested my other diverter valve, it responded the same way my original valve did. I guess it's time to get a billet valve.

Paulyy

did you try what i said?

doabarrelroll

Couldn't I just remove the banjo bolt of the IC pipe to check that?