20 F150 5.0 OBD question

Discussion in '13th Generation F-Series : 2015 - Present' started by mchapmanjr70, Dec 28, 2021.

  1. mchapmanjr70

    mchapmanjr70 Junior Member

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    Hey guys,

    I’ve been an F150 owner form 30 years, and usually do my own work, but I came across something on my ‘20 5.0 that I’m having problems tracking down.

    I’ve been getting P0172 and P0175 errors for a couple months, indicating both banks are too rich. The engine is stock. I tried to reset it several times and let it relearn, but…

    I broke down and had the dealership run it down. All they were able to tell me after 4 hours was that it wasn’t the fuel pump, sending unit or EVAP canister/sensor. They said it had to be on the fuel rail.

    I took it home, searched the internet some more, then set a day and replaced the upper injectors, fuel rail pressure sensor, and MAP sensor. Then I set the PCM to relearn. Within 24 hours I was getting the same error codes.

    Any ideas of what I could be missing?

    Thanks in advance…

    Michael


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  2. MarkVietNamEraVET

    MarkVietNamEraVET Junior Member

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    Disconnect ground cable from battery & make sure it is away from negative post. Connect a jumper wire from positive post to disconnected negative cable & let it set for 3 minutes. This will enable your computer modules, sensors, etc. to clear completely. Let us know how it goes, thanks, Mark
     
  3. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    How long has it been since the MAF was cleaned?
    Clean the MAF with approved cleaner,
    follow directions.
     
  4. mchapmanjr70

    mchapmanjr70 Junior Member

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    The truck has 40k, mostly highway miles. Believe it or not, since I thought MAF sensor first, this truck does not have one.


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  5. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    @mchapmanjr70

    Pressure and Temperature. - MAP

    Since you already went over upper injectors, fuel rail pressure sensor, and MAP sensor.

    • Engine mechanical problems
    • Defective Oxygen Sensor
    • Defective Fuel Pressure Regulator <-------
    • Defective Coolant and/or Air Temperature Sensor
    • Thermostat is stuck open
    • Ignition Misfires
    • Defective Throttle Position Sensor
    • Defective or restricted fuel return line
    Were the other ticks to hit.

    Are you able to measure fuel pressure?
    Rent-a-tool ... You know which one without me calling out a name.
     

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