2007 F250 SD 5.4 gas Inter mil codes po171 and po174. No vac leaks found. New Intake manifold. now hard shift 1-2 and code po191 came up also. bad fuel pump? low pressure?
you can check fuel pressure
see specs below
fuel pressure sensor can also be bad
33.7k questions
32.5k answers
1.3k comments
23.0k users