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P0171 and P0174 caused by low fuel???

Discussion in 'Stock 1995 - 2001 Explorers' started by admonroy, February 20, 2014.

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    1. admonroy

      admonroy New Member

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      Hi all, I'm quite new here, so I apologize if I'm not posting on the right place. That begin said, I hope somebody can help me out.

      The truck is an explorer 98, V6, vin X.

      I've had this codes since FOREVER, but I finally want to get them fixed. When it comes to drive, the truck is just fine. Lately it has rough idle, but I believe that's because of a bad IAC, because when I clean it the problem goes away for a few days.

      I read a response from 2000StreetRoad for "Lean condition procedure", and when I got to the Fuel pressure test, this is what I got:

      1) switch on/off a few times (without running): Pressure builds up to 35psi.
      2) Engine at idle with vacuum line connected to the FPR: 28psi
      3) Engine at idle with vacuum line disconnected to the FPR: 38psi
      4) Engine at 3000 rpm: 28psi (it does go up when rapidly accelerating, like to 35psi or so)
      5) When I shut off the engine, the pressure does not go down, actually for the first 10 minutes or so, it goes up, from 28psi to 35psi. After that it goes back down to 28psi, but it takes over an hour or so.

      The questions here are:

      1) is it possible that just for being 2psi under specs I'm getting the lean codes?
      2) If so, what could cause it, the fuel pump itself, maybe the pressure regulator?

      From what I've read, most people automatically says "just change the intake gaskets", and I was going to do that at first. But even the most horrible gaskets wouldn't affect fuel pressure (would they?), hence, I decided to correct that first. Makes sense?

      Please help!!!


      Regards,

      AD
       
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    3. joe doe

      joe doe Active Member

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      vin x is the ohv engine i believe .those codes almost always point to 1 thing on the ohv engine .

      the upper plenum oring gaskets ,not the intake gaskets themselves but the upper intake gasket ring set .

      they look like this

      [​IMG]

      see that set on the bottom?thats what goes bad ,they get compressed over time and no longer seal properly and let air pass by causing the dual lean codes .
      you can probably get away with just replacing those .
      thats what fixed mine when i got those codes .only other thing that would give both those codes would be a large vacuum leak .

      good luck .
       
    4. joe doe

      joe doe Active Member

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      other indicators would be shaky idle on cold starts that goes away once warmed up .when the seals are cold they shrink letting air get by ,once warmed up they expand enough to create a seal again and the idle gets better .
      classic signs
       
    5. drdoom

      drdoom Well-Known Member

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      got those from a clogged fuel filter once...
       
    6. admonroy

      admonroy New Member

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      What about the low fuel pressure? were you experiencing that as well? Also, have you seen any step by step procedure to change those?

      AND.. I forgot to mention, I replaced the fuel filter just in case, but that didn't fix it.


      Regards,

      AD
       
    7. Anuk Su Namun

      Anuk Su Namun New Member

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      Could these gaskets also cause a strange coolant lost has well??
      I have no leaks visually radiator new, water pump new too and bottom hoses all new but my coolant disappears a gallon every two weeks roughly and have no idea why
       
    8. admonroy

      admonroy New Member

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    9. joe doe

      joe doe Active Member

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      roy , your fuel pressure looks normal to me .2psi under spec is nothing to worry about .
      does your ex have a shaky cold morning start condition that clears up when it warms up?

      you could try clearing the code when the truck is warm ,then see if the code comes back on the next cold start .(like a cool morning ,clear the code after the last nights run).

      my ex has 165k on the original fuel pump and its still going .
       
    10. joe doe

      joe doe Active Member

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      no.....that would be head gaskets or timing cover gasket .take a flashlight and look around the block just under the heads ,if you see signs of antifreeze weepage then thats your issue .
      but dont be alarmed just yet it could be many other things as well.
      leaking hoses for one ,leaking heater core ..ect,ect
       
    11. admonroy

      admonroy New Member

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      Thanks Joe,

      I'm goin to clear the codes tonight and see what happens tomorrow. I'm at 192k :) I was concerned the pump was giving up. The gaskets are only about $28, so it will not hurt my wallet much to go that way.

      Regards,
       
    12. admonroy

      admonroy New Member

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      Hello Again Joe!! (or anybody else)

      I can't figure out how to paste a picture here, (I don't see the "Manage Attachments" button)....

      But!! I disconnected everything of the TB to take it off and replace the gaskets, and there is a connection right under the IAC, seems to be a gas line coming from the the base of the AGR. It's solid pile, like the fuel rail. I don't know how to disconnect that one. I've tried gently pulling strait up, but it doesn't seem to be working. Can you tell how is that suppose to come off??

      please HELP!!

      AD
       
    13. fatpadre

      fatpadre New Member

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      Quesion? 1999 Explorer 4.0 V6 has constantly recurring P0171 and P0174 codes. I'm planning on replacing the O rings on the intake, but have noticed that the downstream O2 sensor constantly reads up around 0.8 after warmup. Is this correct or should it read low? Should it be replaced? Thanks for any reply.
      I own a 1994 also, with clutch problems. No questions on it right now.
       
    14. admonroy

      admonroy New Member

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      nevermind to this one... I managed to disconnect it, not sure if I did it the right way or not, but it's done.

      Now... by NO MEANS I'm a mechanic, I just google stuff, read and try to get this done. That being said... after removing the manifold, Other questions raised. Is it normal for it to be extremely greasy and gunky? And also, I only located the ring gaskets, but the other one that looks like a solid peace, I don't see that one anywhere. Please see the video bellow, and let me know what's next.

      http://youtu.be/9a2TniZ7qj4

      Thanks!!

      AD
       
    15. joe doe

      joe doe Active Member

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      pick those rings out with a pick or a fine blade ,whatever it takes to get them out .
      press the new ones in their place .if you did not have the "phenolic spacer"then no need to worry about it .it may be attached to your upper intake still .
      anyway its a non issue,your at the suspect part .just replace them and reassemble .
      i wouldnt bother trying to clean inside the intake runners ,best to do that once assembled and just use a good 02 safe intake cleaner spray .

      the other part coming off your egr will need to be replaced if you broke it .i believe its used to send hydrocarbons to your intake to be burned .

      i had my mechanic do mine so i didnt have to deal with it .just be sure you replace the part its there for a reason .and without it you could still throw a code .

      keep going your almost there .
       
    16. admonroy

      admonroy New Member

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      Thank you Very much Joe,

      I triple checked the "phenolic Spacer", and definitely it wasn't there. Maybe other models have it or maybe under the fuel rail? Anyway.... Thank God I finished!! :) so far it runs nice and steady, I hope that was my issue, if for some reason it wasn't, well... the gaskets were REALLY bad, they were so hardened one of them actually broke like it was hard plastic.

      I looked up the mysterious part :) it's the "EGR valve Inlet tube", and after seeing the new one, it doesn't look broken after all, btw, the gasket kit included an "O" Ring that goes right there, so I just replaced that one and put it back. Here is the part just so you know.

      http://www.ebay.com/itm/1998-2001-F...Parts_Accessories&hash=item2ec72cf240&vxp=mtr

      If codes come back after a few days, I'll write back!

      Thanks again!!

      AD
       
    17. joe doe

      joe doe Active Member

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      great! hope your all fixed up now .do write back in a few days .it would throw a code in a couple days driving if it was going to throw one .

      great pride in knowing you done something yourself too .congrats.
       
    18. admonroy

      admonroy New Member

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      Well... I've driven all this week to work and so far it feels good, no check engine light on or rough idle. I'm making a 400 miles trip this weekend for the ultimate test, but I think that was it, I think it'll be alright.

      If I had know this was going to cost me only $30 and a few hours, I would've done it 3 years ago!! :D

      Thank you SOO Much Joe!


      AD
       
    19. joe doe

      joe doe Active Member

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      glad i could help .and report back after your trip .
       

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