Was driving my lancer evolution today and noticed i wasn't making boost as efficiently. Got home and did a boost leak test. Turns out this little mechanism on my throttle body is the culprit. I'm not even sure what it is. Can i just take the screw off, put some teflon tape around it and put it back in? Or should I replace the seal instead?

The reason why my throttle body looks different compared to OEM is because it rotated since I'm in running a magnus intake manifold

 

"Wax pellet thermo valve", that's what I got from comments on this video from boostedfilms:


Apparently this will regulate the coolant flowing through the TB

 

thanks i saw that. i took mine apart, which was actually pretty clean but the seal has pretty much fallen apart and cracked upon removal. So I replaced it with a similar one from the harbor freight pack of o-ring seals. Luckily one of them was really close to the size and thickness. Installed it back in there and it seems to be holding up. Will boost leak tomorrow (or day after) whenever it isn't 5 degrees below freezing outside!