1999 Ford F-250 P0171 and P0174 codes

  • 1999 FORD F-250
Engine Mechanical problem
1999 Ford F250 V8 Four Wheel Drive Automatic

hi, this is sam ryan and I am the owner of a 1999 ford f250 lariat. My truck has been shaking is at a low and sort of ruff idle. Also the codes that I have been recieving from the engine computer suggest that bank two is lean on fuel. I suspect that it is either the coolant temp. Sensor or the mass airflow sensor. I have also tried running the truck without the MAF sensor (mass air flow sensor) and it seemed to run fine but it might just be me. And when I check the continuity of the MAF it tells me that it might be bad. But the book that I have relied on for years I now showing me things that dont match my engine. If you could also tell me where to find the coolant temp sensor.
i will check this thread later tonight.

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have the same problem?
Wednesday, December 30th, 2009 AT 3:20 PM

1 Reply

P0171/P0174 a lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (Use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (Try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)
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Wednesday, December 30th, 2009 AT 5:27 PM

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