Stoichiometric AFR
14.7:1 — ideal air-fuel ratio for gasoline.
The stoichiometric ratio is the air-to-fuel mass ratio at which both are completely consumed. For gasoline — 14.7:1, diesel — 14.5:1, LPG — 15.5:1. The ECU tries to hold this in closed-loop; deviations show up in fuel trim.