Boost Control Installation
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This covers the selection, connection and wiring of the boost control solenoid.
Boost Control Solenoid
While almost any solenoid can be used for boost control, it is recommended to use a 3 way solenoid designed for boost control.
Solenoids can either be normally open or normally closed. A normally open solenoid has the advantage of not running until boost needs to be increased, but has the disadvantage of not controlling boost at all if the solenoid or hoses fail. An ECU boost cut is recommended to prevent damage if this occurs. A normally closed solenoid will run more often but will limit boost to the spring pressure if a component fails.
Connecting the Solenoid
See ECU Connectors for information on inserting the boost control output pin into the ECU connector.
It is recommended to use an external wastegate with two ports (on both sides of the diaphragm). This is by far the most common type of wastegate. For other configurations typically the boost control solenoid operates as a bleed valve, venting pressurized air from the wastegate to the atmosphere.
There are several different pressure sources which can used to control the wastegate:
Each pressure source has advantages and disadvantages - try using a pressure source from the intake manifold first, and then experiment with other sources if the boost is not stable.
Wiring the Solenoid
The solenoid has two wires, with no polarity (it does not mater which wire is used for each connection):
Solenoid Suppression Diode
Do not use a suppression diode. The ECU has a diode built into the output circuitry.