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subaru boost control

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can somehow help me better understand how Subaru boost control works, I have the duty cycle at 0 across the table and the boost targets at 11 psi but I'm still hitting 17 psi at higher rpm? using a cobb 3 port solenoid and a vf39 stock internal wastegate turbo.

Depending on what kind of modifications are done to the rest of the car, the stock internal wastegate might not be able to flow enough gas to control the boost level properly, or a restriction at the turbo outlet might be creating pressure here, 'blowing' the wastegate shut. To confirm if your setup can control the boost properly, remove the solenoid from the plumbing and run a boost line directly to the wastegate actuator. This is the lowest boost level you will be able to run. See if that setup results in a steady boost pressure across the rev-range.

So run the boost line from the compressor housing to the wastegate acuator?


Most likely, you don't have enough restriction in your exhaust or you need a bigger wastegate. What mods are done to the engine?

Cp pistons, Manley high beam rods, bc 272 cams , bored 20 over, milled 20 over, 1000cc injectors, tgv deletes, Perrin intake, Perrin turbo inlet , Sti inter cooler full cat less exhaust and up pipe

It's probably that catless exhaust you are running, with the stock wastegate. Unless your timing is super retarded up top, that could also contribute to boost creep.

The timing is retarded quite a bit, I’ll try that but if not that there’s a turbo smart iwg actuator upgrade, do you think this could help at all? 7psi spring

It's not likely to help much. External gate or more restriction are your choices.

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