Iowa Chapter Director
Join Date: Jul 2002
Location: Ames, Iowa
that screw just slightly opens and closes the throttle body plate. By changing it, you change the position of the throttle shaft, which turns the TPS slightly, which can throw off it's idle voltage reading, which should be around .96-.98V at idle.
1988 Notch Mustang: - 438W, direct port n2o, t56
2003 SVT Focus: - SCT X3 tuner