Mister Quickie

The way (I think I remember) it was explained to me was that when the vacuum lines are closed (see blue circles highlighting pluged lines) that then the wastegate is completely open and therefore no restrictions on amount of boost, power, etc.

As you can see in the picture the boost solenoid has been cut out of the equation because it's stuck in a certain position due to computer short that is restricting power. I didn't know if I should use a coupler to marry the vacuum lines together for maximum airflow or to plug them up to stop any flow.

If the theory in Paragraph 1 is true then I should plug these lines as I have for max boost/power ... ?

Dougs951S

With the line to the wastegate blocked off, there will be no control signal to the wastegate and technically boost would be uncontrolled. With an unblocked line to the wastegate and no boost controller in use, you'll just be running on spring pressure. But, without a signal at all, you are relying on the pressure in the exhaust to open the wastegate, which is not how they are intended to operate. Who knows how much boost you'll get? It depends on the turbo, exhaust setup, wastegate, ect. It might be ok, it might be way too much.

But to answer your question, those lines should be joined with a coupler so you can safely run the car on spring pressure.

One more thing, your understanding of how the wastegate works is backwards, maximum boost pressure is achieved when the wastegate is all the way closed. It's just a valve which is normally held closed by a spring (and opens when the pressure in the line going to the wastegate is equal to the spring pressure, 10 psi and 14.7 psi are common for aftermarket wastegates, while the stock wastegate spring is ~4 psi), that vents backpressure in the exhaust; which deprives the turbine of what would otherwise be a quickly escalating, uncontrolled increase in speed/boost. With the energy being vented away from the turbine, its speed (and therefore boost pressure) can be controlled. With the wastegate held all the way open (possible realistically only with a failed wastegate) the car will definitely not make pressure with anything resembling a stock header/crossover/bolt on turbo setup.

HICKS

Delete.

Mister Quickie

Ok I've been searching/reading on his and can't seem to get a thorough understanding of what "spring pressure" is.

I'm guessing the function of the wastegate is to relieve boost pressure. Right now, the lines are blocked and since there's no control signal to the wastegate, there's no relief of boost pressure and so while I'm getting the maximum amount of boost, the only "controller" in place is basically how hard I'm stepping on the gas, is this correct?

Now if I join the two lines with a coupler, the spring pressure (which I don't understand as well as I'd like to) can control this boost pressure to a degree ... ? Then the question is how does it control the boost pressure and then would I be getting maximum boost?