Vital to the Idle! The little recessed screw on the top of the throttle body allows you to adjust the idle, but over time the o-ring may get worn out, or the screw or particularly the cap may get lost. These are easily replaced. NOTE: There are only one of each part on a throttle body.
Parts sold individually as follows:Idle Adjustment ScrewIdle Adjustment O-RingIdle Adjustment Cap(for the cap, choose between build thru June91, and build July91+)
The oring goes at the top of the screw, in the groove just under the cap end.