explain this wga to me
 

https://www.miataturbo.net/attachmen...1&d=1370645356
09 saab 9-3 came in today for service, and I noticed this wga with the hose plumbed into the intake snorkel. How does this work?

I'm guessing that's a EBC solenoid or something to otherwise monitor and control boost. Interesting that they swapped the engines around in the '03+, I know the '94-'02 900/9-3 had the exhaust in the front, and intake by the firewall. They still had a similar box on the WGA, I've always assumed it was for boost control.

It's a GM ecotec 2.0l. I just don't understand what kind of source they would be getting from the the airbox side of things?

Maybe it's just to vent the air used to open the wg? I love looking at oe turbo engines and getting ideas, they always run so smoothly.

The speed3/6's are the same, I believe they work by venting to the intake to allow more boost and close to allow the waste gate to open. At least that's my understanding of it.

Think of it like a BPV versus a BOV. The solenoid cant simply vent metered air with out messing with fuel calculations so they vent it post-MAF as to not loose metered air. There is another nipple on the wastegate that goes to the pressure side somewhere. As mentioned before the Mazda DISI engine uses a similar system.

Yeah. Thats the same boost control solenoid that comes on the efr, that line is labeled vent and they tell you to put behind an air filter because theres a chance you can suck dirty air in somehow. That tube just vents the air that was inside the wga when the noid switches.

If thats the 2.0 ecotec its an odd ball engine. There is two different turbos that could come on it, the "high boost" and normal. Its basically the 2.0 SC engine from eh early cobalt SS's with a turbo on it instead, it was only offered a couple years.

where's the third hose on the solenoid go? (the one under the connector towards the firewall)

Intake manifold, the only metal intake manifold that fits on the early/non-DI ecotecs that doesnt also have a supercharger bolted to it.

so. the intake tube is just the vent.