Ford po171 po174

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  • redrider47
    Junior Member
    • Oct 2014
    • 1

    Ford po171 po174

    2001 f150 v6. Replaced upper intake gasket a yr ago and P0171 and P0174 keeps coming back along withP0325 knock sensor code. Anyone out there with ideas?
  • Witsend
    Banned
    • Nov 2012
    • 2942

    #2
    Referring to TSB 05-22-6, Besides the o-rings I believe it also includes replacing the isolator bolts (or at least the rubber grommet isolator parts of the isolator bolts that crush , harden and lose some downward pressure for the upper part and making sure none of the EGR floor ports of the lower intake are plugged with carbon. I would see if the freeze frame data for the lean codes was set with engine during warm up or when it was fully warmed up. Sometimes having a high mileage Turd that burns oil ,has worn out 5w-20 engine oil with blow by, aftermarket PCV valve, dirty fuel injectors, dirty MAF sensor, leaking EGR valve, not seating fully and a need to also do your lower intake gaskets this time , and replacing a bad knock sensor that might be causing the timing to retard more than normal, the list is pretty long.
    Did you smoke the Intake , consider a possible leaking brake booster or EVAP purge control valve, ever check the Baro pid reading to see if hertz reading is what you would want to see for the altitude above sea level you are at ?
    Last edited by Witsend; 10-15-2014, 10:25 AM. Reason: Tourettes is Treatable

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    • Prezauto
      Member
      • Dec 2014
      • 42

      #3
      Curious to know how this turned out. Had a similar encounter with a 03 F-150 4.2 v6. Also had p1131 & p1151, which had me suspecting downstream o2s. Haven't replaced intake gaskets & isolator bolts yet. Smoked it & had a tiny amount from under intake & fair amount coming from EGR valve.

      Wasn't sure if EGR should have had any "leakage" and wrote off the trace from under intake as maybe it was blown back from EGR since blower was running on my shop furnace 8 ft away.
      John

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      • Joe Rappa
        Snap-on DSD
        • Aug 2007
        • 2050

        #4
        Originally posted by Prezauto
        Curious to know how this turned out. Had a similar encounter with a 03 F-150 4.2 v6. Also had p1131 & p1151, which had me suspecting downstream o2s. Haven't replaced intake gaskets & isolator bolts yet. Smoked it & had a tiny amount from under intake & fair amount coming from EGR valve.

        Wasn't sure if EGR should have had any "leakage" and wrote off the trace from under intake as maybe it was blown back from EGR since blower was running on my shop furnace 8 ft away.
        Ford EGRs normally leak smoke during a smoke check. Plug the vacuum hose to it and it will stop. On fords with P0171/174 the first thing I do is check the freeze frame. If it is happening under load the next thing I check is the Baro reading. If it is low I know to suspect a dirty MAF.

        What do your fuel trims look like at hot idle, and under load?

        Joe
        "You don't build a reputation on what you're going to do"
        Henry Ford

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        • Prezauto
          Member
          • Dec 2014
          • 42

          #5
          Originally posted by Joe Rappa
          Ford EGRs normally leak smoke during a smoke check. Plug the vacuum hose to it and it will stop. On fords with P0171/174 the first thing I do is check the freeze frame. If it is happening under load the next thing I check is the Baro reading. If it is low I know to suspect a dirty MAF.

          What do your fuel trims look like at hot idle, and under load?

          Joe
          LTFT on both banks were maxed out @25-29, ST was about -2-2 hot idle, under load LT was same, ST was 3-8. Code setting was at idle. MAF was checked and cleaned or replaced earlier.
          John

          Comment

          • Prezauto
            Member
            • Dec 2014
            • 42

            #6
            Originally posted by Prezauto
            Curious to know how this turned out. Had a similar encounter with a 03 F-150 4.2 v6. Also had p1131 & p1151, which had me suspecting downstream o2s. Haven't replaced intake gaskets & isolator bolts yet. Smoked it & had a tiny amount from under intake & fair amount coming from EGR valve.

            Wasn't sure if EGR should have had any "leakage" and wrote off the trace from under intake as maybe it was blown back from EGR since blower was running on my shop furnace 8 ft away.
            Ironically, I have 00 Expedition 5.4 with same codes. What are the odds two different fords with same codes in a few weeks?

            Edit:LOL, just realized the odds may be good for some, but in a small county with no dealers & two shops that specialize in fords (with OE tooling), and 20 shops in A 15 -/+ mile radius....pretty slim. Expy has intake leak on both banks, so easy diagnosis on that one.
            Last edited by Prezauto; 01-21-2015, 03:34 PM.
            John

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            • Joe Rappa
              Snap-on DSD
              • Aug 2007
              • 2050

              #7
              If it is happening at idle and under load, it makes me think MAF, or maybe incorrect injectors (like flex fuel ones in a non ff engine). Less likely it is a vacuum leak if it happens under load.

              Joe
              "You don't build a reputation on what you're going to do"
              Henry Ford

              Comment

              • Prezauto
                Member
                • Dec 2014
                • 42

                #8
                Originally posted by Joe Rappa
                If it is happening at idle and under load, it makes me think MAF, or maybe incorrect injectors (like flex fuel ones in a non ff engine). Less likely it is a vacuum leak if it happens under load.

                Joe
                I agree, vacuum leak has less effect under load since they are normally of a fixed size. Although, you can feel a misfire at idle in gear, as with a vacuum leak. Injectors have never been changed.
                John

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                • Witsend
                  Banned
                  • Nov 2012
                  • 2942

                  #9
                  If I had original Ford tooling I would definately run a relative compression, power balance and relative fuel injectior flow tests , check misfire history before pulling either intake off. Check DPFE voltage KOEO and KOER at idle, might have EGR valve not completely seated closed if voltage is higher than 1 volt while idling .Also regardless of whether the MAFs were cleaned or even replaced before, recheck the Baro readings and see if it agrees with what it should be at your altitude above sea level. Pinch off brake booster vacuum hose and block evap purge flow tube and see if trims drop also.Seen lots of causes of hi fuel trims at idle on F'ed up old Fords

                  Comment

                  • Prezauto
                    Member
                    • Dec 2014
                    • 42

                    #10
                    Witsend, your posts always have that humored wording & phrases like "F'ed up old Fords" that make me LOL. Had 5 of those Fords in the last couple of weeks, 64 Falcon with bad gas & faulty new fuel pump, 98 f-350 7.3 with p0344 turned out bad IDM, 02 Explorer with worst rear wheel bearing I've seen in my life (only 2 rollers left) it destroyed the knuckle & rotor, axle, upper ball joint...and the 2 previously mentioned. Very rare given mine is not one of the shops that specialize in Fords.
                    John

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