Never saw a separate fuel flow sensor in an automotive application, but fuel injector is technically an orifice flow meter in this calculation method (pressure

Never saw a separate fuel flow sensor in an automotive application, but fuel injector is technically an orifice flow meter in this calculation method (pressure differential is constant and you calculate how much fuel is flown through orifice by measuring time it is open). Sure, when orifice size is reduced by lacquer depositions or dirt it will cause measurement error. But it will also cause increasing fuel trims (to the point when CEL goes on) and bad driving performance when fuel trims don't apply