what is the round sensor on the passenger side of the engine bay just infront of the intercooler with 2 vacuum lines and a electrical connector coming out of it? i always thought it was some sort of boost controler but i t can be or atleast i wouldnt think so one vacuum line recieves a boost signal the other a vacuum. can some one tell me what it is?
It's the stock Boost Control Solenoid, better known as the BCS.
how is it that it controls boost when the wastegate actuator has a direct boost signal from the compressor outlet?
The tee off the compressor housing, thru the BCS, and back to the compressor inlet creates a "leak" in the boost signal to the wastegate.
The BCS controls the "amount" of the "leak" by pulsing to regulate the "leak", thereby regulating boost.
Careful. They break easy.
I don't like them and often replace them with Gillis type valves.