Cross-Fire Injection was GM's first throttle-body fuel injection on the F-body, debuting on the 1982 Camaro Z28 / Trans Am as the 'top-tier' V8 option ahead of the LG4 four-barrel. The system: two throttle bodies on a tunnel-ram-style intake, alternating fire to keep the inlet velocity up. In practice the system fell short of period expectations — drivability was acceptable but power was not meaningfully ahead of the four-barrel.
Cross-Fire was discontinued for 1984; the LB9 TPI launched for 1985 with a fundamentally different multi-port system. The LU5 lives on mostly in cars that have been retro-converted to a Q-jet or to TPI; finding an unmodified original is increasingly rare.