P0171 FORD -I have two Ford E-350's ('98 & '99) (86kand 198k mi) that both ping almost constantly.

Question

EGR is (?) ok, rattles, not stuck. hose holds suction. MAF sensor sprayed with special cleaner.
No loose hoses. no visible cracked elbows, etc.
So many parts contribute to mixture control: where to start? I have two vans doing Same thing.

thanks

Answer 1

P0171 system lean bank 1

Check the fuel pressure, engine running the pressure should be 28psi to 45 psi, A vehicle that is overheating will also code po171 , so cooling system should also be check,