How are the butterflies opened? Does vacuum keep them shut and then releasing it opens them? or does applying vacuum open them?

 

You can play with the acuator, just reach in and move it. They're normally open, then they close at the stock RPM setpoint IIRC.

 

with an RPM switch / shift light

/thread

 

Did you even read the post? I know how to control it... i was asking how it works.


Anyways i figured out my issue....on my old escort i just ran a vac line to the actuator because the vacuum would hold them closed while cruising and as soon as boost came on they'd open. Worked well and i tried doing the same to the miata but it felt choked up all the time. I thought maybe on the miata they used vacuum to open them instead but then i realized the line i used ran straight to the vac reservoir so the vics was being held closed all the time.....oops.

 

Low revs = no vacuum applied
High revs = vacuum applied via ecu controlled rpm switch.