20 F150 5.0 OBD question

[mchapmanjr70]

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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[MarkVietNamEraVET]

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

 

[Roush PSD Interceptor]

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

 

[mchapmanjr70]

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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[Roush PSD Interceptor]

@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.