What is an EVC?

EVC - Electronic Valve Control

This device is a basic closed-loop process controller. Its operation is very similar to an electronic cruise control device. You input a desired boost level, and it monitors the actual realtime boost pressure. It then adjusts wastegate opening to maintain a stable boost pressure (supposedly) as engine load and RPM changes. Without a closed-loop control that incorporates an integral correction factor, boost pressure will always vary *somewhat* depending upon engine load and speed. The EVC isn't perfectly "tuned" for all possible engine/turbo configurations, and it is prone to under/over correction at times. The wastegate control is achieved by modulating a solenoid that regulates the amount of air that reaches (and thereby opens) the wastegate.

There are many styles of EVC. Importnat to note that ECMLINK V3 can now control boost as well by using the stock boost control selenoid wires and an aftermarket selenoid.