In an intake manifold that has charge-motion-control valves (CMCVs), a gap exists between the flapper valves and the wall of the intake runners. Although the gap is maintained as small as practical, it cannot be eliminated because manufacturing tolerances and temperature variations to which the intake manifold is subjected must be accommodated to prevent binding of the flapper valves. Some flow makes an end run through the gap leading to undesirable fluid mechanics. Disclosed herein is a seal that is positioned to rest gently upon the flapper valve near the gap such that the gap is substantially sealed off while applying a modest force on the CMCV so that the actuation torque is minimally impacted. The seal has a press-in-place portion inserted into a pocket formed in the manifold to hold it in place and a lip portion that extends out from the press-in-place portion to obstruct the gap.