| I'm trying to understand the Z's boost control setup. As I understand it, the Z's stock turbos have wastegate actuators that will open around 7psi. If a hose was run directly from the high pressure side of the intake tract (after the compressor wheel) to the wastegate actuator, the wastegate would open around 7 psi and your boost pressure would be limited to that amount of pressure. So Nissan put boost control solenoids in place to give an element of control to the boost. When the solenoids are open (normal operation) some of the pressure in the hose is allowed to bleed back into the low pressure side of the intake tract (after MAF but before the compressor wheel) in order to lower the pressure going to the wastegate actuator, therefore raising the boost pressure that the turbo makes. By changing the ratio of air that's allowed to be bled away from the wastegate actuator vs. the air going to the wastegate actuator, we can change the amount of boost that the turbo makes. This works just like a voltage divider in an electric circuit:
 You change the ratio by resisting the flow in the different paths. In the electric circuit you accomplish this using resistors; in the Z's vacuum line circuit we use boost jets. When the ECU detects detonation it's able to close the solenoids, preventing the air from bleeding off into the intake tract. This makes the wastegate actuators open at their default setting of 7 psi. People often install aftermarket electronic boost controllers which use their own solenoid and eliminate the need for the Z's boost control solenoids. Here are my questions: Do the Z's boost control solenoids only work when they detect detonation or when the car is warming up, or does the ECU also use it to smooth out the boost curve?
Are there any provisions in the ECU for controlling the solenoids or is it a locked-down setting that you can't change?
Do the solenoids only act as open/close switches that you have to control with PWM or can they open at varying degrees?
Why don't people use the stock Z boost control solenoids like they would with aftermarket controller's solenoids and control the boost that way? Don't any boost controllers interface with our boost control solenoids?
Do any boost controllers get an input from the detonation sensor so that they can pull boost back when they detect trouble?
Thanks
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Boost control solenoids and boost control - 
