How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask James Your Own Question
James, Ford Technician
Category: Ford
Satisfied Customers: 3628
Experience:  Ford Senior Master Tech, Ford gas and diesel expert, ASE Certified
Type Your Ford Question Here...
James is online now
A new question is answered every 9 seconds

Got codes p0171 and p0174, system too lean, changed out fuel

Customer Question

got codes p0171 and p0174, system too lean, changed out fuel filter and iacv and still no change
JA: Is the fuel filter an external one, or is it inside the tank?
Customer: external
JA: What is the make/model/year of your car?
Customer: 2003 f150 with a 4.6
JA: Are you fixing your F150 yourself? What have you tried so far?
Customer: yes, checked air filter, changed out the fuel filter and changed out the idle air control valve, checked the hoses but they all seem fine
JA: Anything else you want the mechanic to know before I connect you?
Customer: it has arough idle and sometimes stalls
Submitted: 7 months ago.
Category: Ford
Expert:  James replied 7 months ago.

Hello, To correct this concern you want to get a can of CRC mass air flow cleaner. You remove the mass air flow and spray it very good with the cleaner. Let it air dry and reinstall into the ve3hicle. Have the battery cables disconnected for 10-20minutes. This will reset all memories inside the PCM Test drive the vehicle and your concern will be fixed. Overtime the mass air sensor needs to be cleaned from all of the dust that builds up on it.

Expert:  James replied 7 months ago.

If you have further questions please let me know. Also please remember to rate my answer so I get paid for helping you.

Customer: replied 7 months ago.
i cleaned the mass air flow sensor and the throttle body and I still get a rough idle. can it be an ignition coil even though I'm not getting a code?
Expert:  James replied 7 months ago.

Has the idle been rough the entire time? If you tip into the throttle does the vehicle run smoother off of idle?

Customer: replied 7 months ago.
you just tip the throttle a little and its good.
While driving the vehicle is fine, but when you come to a stop, it drops in rpm and goes up and down
Expert:  James replied 7 months ago.

On the passenger side valve cover I would carefully inspect the PCV valve for it being cracked and broken.