Hello all Im brand new to the site cause Im brand new to a 05 f150, The truck has a new motor new tranny and radiator and pretty much every thing that goes on the motor is new. Been driving it for about two months now and all of a sudden it starts backfiring on take off and has hesitation added to it, Needless to say the check engine light came on and on my cheap code reader I get codes p0190 & p0191. I have checked many times for vac leaks and cant find any and I cant find any other things that could be messing up. So not knowing were and what I should be looking for I dont know and any help would be great. I checked code site and it all kind of points to something to do with fuel rails or sensor but I just dont know if thats right or if it could be something totally different. Thanks for any and all help. Its also a 5.4 triton motor plus supercab if that helps also before I erased the codes I was getting p0171 & 0174 but they didnt come back

 

Nobody has a clue? What a bummer

 

No personal experience with your specific situation. But I would recommend trusting the codes from the PCM. It is the closest to the actual problem, and P0190 and 0191 are for the fuel rail sensor circuit (wiring open / short / poor connection) and device malfunction.
Fuel rail pressure is directly related to the amount of fuel delivered in a given injector pulse width --- if pressure sensed by PCM is off (TOO LOW), PCM will lengthen injector pulse width (add positive fuel trim). Fuel trim > sum of 30% will trigger lean codes P0171 & 0174.

If you're still having troubles - I don't think I would be looking for a vacuum leak.

 

Thank you very much just got the new rail sensor today so I hope thats the problem or the search will continue

 

Put in the new fuel rail sensor and that was not the problem. Truck is getting harder to start and it starts to run rough after you have been diving it for a while and still getting fuel rail codes. Any other clues as to were I should be looking. Thanks for any and all help.

 

 

I think the cats new and I will find the purge evap sensor. Thanks a lot

 

Purge Evap 'sensor'. I don't think you will find one of those. The 'Electronic Vapor Management Valve' (More commonly referred to as the Evap Purge Valve) is located on the firewall just above and the Break Booster. It's a normally closed vapor solenoid valve actuated (modulated open proportionally) by the PCM. The only 'sensor' associated with it is the Fuel Tank Pressure sensor.

Also - the purge valve (or Evap system) is highly unlikely to cause any of the codes you have reported. Just about anything that goes wrong with the EVAP system will report a trouble code related to evap - even GAS CAP OFF. If you question the integrity of the EVAP system and/or purge valve, take the gas cap off and do a drive cycle or two and see if you get a 'Check Gas Cap' indication.

 

Thanks for the great info but what is the most likely cause for me to get those codes then. I just dont know were to start. Again thanks a lot

 

Are you still getting codes? Please let us know specific ones you are getting. You may need to invest in a scanner to see what the computer THINKS is going on. (If you have an Android device w/ Bluetooth, The Torque Pro App is an inexpensive ($4.95) and a Bluetooth adapter can be had for $20.00 to $40.00 bucks.