2016 EF349 and (51498) 2001 FW80

 Based on nominal orbital parameters, this is the result of a backward integration performed with Mercury6 (*) Bulirsch–Stoer run with a 0.05-day step, 1e-12 accuracy, and outputs every 100 days, integrating from JD 2461000.5 backward for 100 M days (~0.27 Myr)

(*) Chambers, J.E. 1999, “A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies,”

The following plot shows the relative velocity and distance following the time when the relative velocity was minimum (other previous minima might of course be present but the uncertainty is very high):

Best wishes,

Alessandro Odasso