Flight of the Phoenix (1965) - The heroic engineer is a German model airplane designer who rebuilds a crashed air freighter.

Threshold (1981) - Jeff Goldblum plays a biomedical engineer who designs and builds the world's first self-contained artificial heart.

Buckaroo Banzai (1984) - A stretch, I think, but BB and the Hong Kong Cavaliers are all techies to one degree or another.

Real Genius (1985) - The heros are physics and CS majors, but that's close enough.