Sorry to sound n00b, but I found this knob on my car tonight while trying to fit the EF Intake box (That's a whole other story though :(), what's it do?
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.