P0305 Chevrolet -

Question

my code reader shows po305 and also fuel system 1 open loop fault cal23.9%

Answer 1

P0305 Misfire number 5 cylinder

23.9 % the engine starving for fuel, When you have a open loop fault the fuel trim are not correct until it is a closed loop system , Check the injector and you should also check the compression  Chevy also recommends for this year make and model is a fuel injector cleaning maintance program.