QuestionI'm getting codes 171 and 174, lean condition on 2003 explorer 4.0.
I've cleaned the mas and iac, and checked fuel pump pressure, 69psi. Chiltons show fuel pump pressure is normal, maybe a bit high for every OTHER year, but 2003 which has maximum at 45 psi.
There aren't any driveability issues other then an occasional failure to start for a few minutes sometimes (it will idle very rough and then shut it off and wait and theres no problem), its had that since new and the dealer never figured it out.
AnswerHi, I would recommend that you find a shop with a smoke machine. While there are numerous explanations/ possibilities fro these codes, the most common are vacuum leaks. particularly the PCV hoses and the lower intake gaskets.
Other possibible causes are oxygen sensors, MAF sensor, Coolant temp sensor, Computor problems, etc
