I would want to straight out some facts about the actuator.
True or False:
1) the ebc opens the actuator by adding pressure to the actuator piston.
2) the ebc close the actuator by adding negative pressure to the actuator piston.
3) without the Ebc, the waste gate will open when the boost pressure overcome the spring tension.

 

Boost controllers to do directly effect the operation of the wastegate actuator. The wastegate actuator is designed to operate off of the air pressure in the boost/vaccum line supplied to it. Based on it's "spring", it will open an close.

If you have no vaccum/boost line hooked up, it will spool endless, since the wastegate has no way of knowing how much pressure the turbo is generating. Boost controllers (electronic or manual), simply "bled" off the amount of air the wastegate sees, allowing you to increase the amount of pressure the turbo puts out.

So for example, say the stock wastegate is designed to limit boost to 15psi. If you have your boost controller set to 20psi, it will "bled off" 5 psi of boost pressure out of the line going to the wastegate. The wastegate regulates boost to 15psi, even though the system is actually running 20.

Hope this helps.

 

Sorry, I still don't understand completely how the actuator works.
My Evc Ez ii is set to max and I'm only hittting 1.35bar(holding at 1.3). Would I be able to get higher boost by replacing the spring with a stronger one?

 

Well, I'm not an expert with the EVC EZii since I've never used it. But upgrading the spring could help you, but not necessary. More likely there is something wrong with the unit, the install, or the configuration. I assure you even some of the crappiest turbos will spool will beyond 1.35 bar. Did you leave the stock BCS in? Does the EVC have a high low setting? These are the most common problems I've seen with electronic boost controller installs.

 

I think the setup is ok. some said the stock spring is set to 0.7 bar, and that's why when I turn off the Evc I still get 0.7 bar peak. This is confusing me, I thought the turbo will spin indefinitely when the Evc is off.

 

No, the wastegate will only allow the turbo to spin to the stock wastegate spring, because it still has a source telling it the amount of pressure in the system. Pull the vaccum line off of the wastegate and it will spin indefinitely. That's bad.

 

Here is a link describe wastegate or wastegate actuator

http://www.autospeed.com/cms/article.html?&A=0770