All go, no show! Atlteast that’s the excuse I use for not having fixed any of the scratches or faded paint…
pcproa, they are vacuum actuated. The CA18DET has a vacuum pump which provides vacuum even when in boost. When the ECU detects the engine at 4200rpm it triggers a solenoid that switches the line so that the actuator sees atmospheric pressure instead of vacuum and allows the valves to open. It seems that either the solenoid is not working or one of the check valves is stuck so the actuator never sees atmo, just vacuum.
As a temporary solution I just disconnected the line to the actuator. The vacuum holds the butterfly valves closed so the ‘fail’ state is open.
Unfortunately I lost a lot of low-end torque but gained back all my top end.