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Check Engine Light: P0171 & P0174

Discussion in 'EEC V' started by purehypeballer, December 6, 2005.

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    1. ivrb

      ivrb Member

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      Found my problem, the vac line that connects to the brake booster was on the wrong connection on the intake, the pcv was on the other switched them now the pcv hose connects straight in and seals, no more cel light
       
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    3. expl0rerct

      expl0rerct New Member

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      Year, Model & Trim Level:
      2000 Explorer XLT
      In my case, my 2000 Explorer XLT with 4.0L SOHC had both P0171 and P0174 codes. As suggested by this post, I bought a can of electrical contact cleaner and cleaned my mass air flow sensor. I also checked and reseated the PCV valve to make sure the fit was snug. I cleared the codes by removing the battery cable negative terminal, and reconnecting it. So far the codes haven't come back for over 300 miles. For the record, I didn't have any rough idling or any indication of leaky upper/lower intake gaskets. I hope this helps. It saved me a lot of money.
       
    4. Keno Biebrich

      Keno Biebrich New Member

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      esos codigos son porque necesitas cambiar los empaques del aire de admision... estos empaques van en el plenum arriba y abajo del riel de injectores.....

      tienes una entrada de aire y no puede controlarla la computadora....es todo!
       
    5. BonesDT

      BonesDT Elite Explorer

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      Red '99 Sport SOHC 4x4
      ¿por qué sucede este post?
       
    6. rscamaro73

      rscamaro73 Active Member

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      Since this was dug up from the grave recently.....did anyone have any issues with upper RPM running with the same codes ? I have a 99 Xploder 5.0L

      I have the same issues, also had a code that I thought was for a gas cap. Put a new cap, code never left. Just put another new cap and cleared codes but when I checked the stored codes it was for the P0171/0174. Have 3 stuck spark plugs on pass side to deal with, and a 1/2 stuck fuel filter.

      But I digress.....to the upper RPM issue....above 3500rpm the truck loses power and doesn't want to go any faster, but when you let off the gas and the RPMs go down you can feel the speed and power pick up.

      I was HOPING it'd be O2's.....but I bet the cat is clogged. I'm at 150K miles as well.

      Thanks for any assistance. I'm going to see what my genius mechanic buddy what he thinks....but that'll be later this week.
       
    7. DannyNon

      DannyNon New Member

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      Year, Model & Trim Level:
      1997 Mercury Mountaineer
      Have a 1997 Mercury Mountaineer with codes. Any possibility of a missing "flap" entire plastic piece at the top of the fuel filler neck being the culprit allowing too much air in?
       
    8. 99Explorer SOHC

      99Explorer SOHC New Member

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      City, State:
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      Year, Model & Trim Level:
      1999 Explorer SOHC
      Bank 1&2 lean P0171 & P0174

      So im pretty annoyed lol. 1999 explorer 4.0 SOHC throwing the CEL p0171 and p0174. I have replaced the upper and lower intake gaskets, PCV, IAC, MAF. CEL is still coming on. I noticed that the left hose off the "T" for the PCV is pinching shut while idling. I have 24 more days til my temporary tags are no longer valid. Please, any advice would be great. Thanks.
       
    9. blackshine007

      blackshine007 New Member

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      This is the same exact issue that I have going on right now on a '98 explorer sport OHV. But there is no vacuum leaks. The MAF has been replaced. The one thing I have noticed that no one brought up was mentioning anything about fuel trim. Which is funny because when I turn the key on and don't start it the fuel trim is at 100% on both banks. When I take the negative and positive off and touch them together to reset fuel trim, the moment I plug in the scanner and look at fuel trim before even starting the truck the fuel trim is still at 100%. When I start it up, about 1 minute will go by until it goes into closed loop. There is no activity from the O2 sensors. The trim on the O2 sensors read 100%. When you unplug all 3 of them, it doesn't set a code. There's battery voltage to the heater on all 3. There's even ground. But on one of the wires there isn't continuity, which is common on the other connectors.We tried wiggling the harness with no success. The funny part about this story is that when all 3 O2 sensors are unplugged, no MIL is set, not even a pending code.



      I'm fresh out of ideas. Anyone wanna take a stab at this?
       
    10. jonmcarr

      jonmcarr New Member

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      City, State:
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      Does anyone know how to secure a replacement "hose" as referenced in DrDoom's picture? This is actually a Y connector that is part of the the IAC or Bypass airflow. Mine is torn to shreds. Local Ford dealer wants $213 for a replacement.

      If no replacement choice other than dealer is out there, does anyone have a repair recommendation?
       
    11. HWBlock

      HWBlock New Member

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      For PO171 / PO174 first item to check is ALL of the vacuum hoses including the PCV system for leaks. This OBD II combination is triggered by the computer calling for additional gas due to a vacuum leak, more gas less milage, engine coughs and sputters when cold. If all OK then suspect the Intake seals.
       
    12. BonesDT

      BonesDT Elite Explorer

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      Not sure if this is obvious to you, but did you scour rockauto.com? If they don't have it, your options become slim.

      As backups, I like to double check with Gates & Dorman's official website. Also check LMC Truck.

      I would then direct my attention to junk yards. I couldn't believe how many Exs are in the PA jys these days.

      If you have the OEM part number, search for it in Amazon. Some dealerships sell parts on there & you'll pretty much get the best stealership quote, but I'm not surprised by that insane price given these are very old models now.

      If all else, get some generic auto hose and get to work with epoxy or electrical tape to get the Y. Whatever you do, please don't entertain that $213. Good luck.
       
    13. jonmcarr

      jonmcarr New Member

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      I have looked far & wide. I checked on used parts, but nothing was available locally (already pulled). I found out that Ford only sells the connector as part of the upper intake assembly, so at least you get something for the money.

      A buddy suggested epoxy to seal the hose. It seems to have worked. The good news, truck is running great and think this is behind me.

      Thanks for the response.
       
    14. Can EX

      Can EX New Member

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      I was getting the same codes on my 99 sport ohv. I changed the intake gaskets today now the truck won't start! Did anyone else have this happen. It cranks and I can smell fuel but the thing won't catch. It did once and shook like crazy at idle. Has this happened to anyone else? I'm pretty sure I've got everything back on and in the right spot's. I did however have the plug wires in the wrong spots on the coil's. I think I have them oriented right now though.
       
    15. seanshad

      seanshad New Member

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      Hi. Check your PCV Hoses routing specially at the trottle body the elbow hose. They tend to wear and cause a vacuum leak.
       
    16. gwedster

      gwedster New Member

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      try replacing the p.c.v. valve

       
    17. rabbit91

      rabbit91 Elite Explorer

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      Bump have same codes after a rough start, curious to here of any successful remedies, going to double check all hoses and clean MAF. I'm surprised no one has mentioned changing the fuel filter... Or maybe I'm crazy
       
    18. KayDee

      KayDee New Member

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      Bam..A hole in the hose

      [​IMG]
      There is a u shaped hose that rubs and there is a hole in it!
       
    19. fritz24

      fritz24 Active Member

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      Powertrain DTC-Service information
      P0171 system too lean bank1
      possible causes:
      1.Fuel System-
      ethanol content in the fuel
      Damage or leaking fuel pulse damper
      Fuel filter plugged or dirty
      Damage or worn fuel pump
      Leaking fuel pump check valve
      Leaking or faulty fuel injectors
      Fuel pressure low, fuel supply line restricted, fuel rail pressure sensor bias
      EVAP canister purge valve is leaking when canister is clean
      2.Exhaust leak
      3.EGR vac hose loose or disconnected
      Valve tube/gasket/solenoid leak
      4.intake air system
      Air leaks after maf sensor
      Vacuum leak
      Pcv system is leaking or stuck open
      Incorrectly seated engine oil dipstick
      Intake air turbulence due to incorrect air filter
      Faulty MAF sensor
      5.secondary air injection
      Damaged secondary air injection system or a mechanically stuck valve
       
    20. PickleLips

      PickleLips New Member

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      For anyone's future reference trying to solve this issue, if your scan tool gives you live data readings like this with 100% fuel trim and 0 o2 sensor voltage, it is an issue with your scanners programming, these are not the actual readings. Sometimes your freeze frame data will still show the correct values for those parameters, so that can at least be some helpful knowledge. I found this one out battling this issue which is still ongoing. I replaced a horribly clogged fuel filter the other day and my mpg shot up to 16 from the usual 11 around town so fingers crossed.
       
    21. rabbit91

      rabbit91 Elite Explorer

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      Bump bump exactly what is happening to me, hopefully you get notified and had some
      Success to fix this that you can share.
       
    22. PickleLips

      PickleLips New Member

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      My issue was a dying fuel pump. These codes are thrown due to either inadequate fuel pressure or a vacuum leak. Do a smoke test and hook up a fuel pressure gauge to figure out which it is. No power at high rpm sounds like lack of fuel.
       
    23. rabbit91

      rabbit91 Elite Explorer

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      That's something I do want to change as preventative maintenance seeing as I'm pretty sure the pump is still factory. Currently on the lookout for a fuel pressure gauge
       
    24. PickleLips

      PickleLips New Member

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      You can rent one from Autozone or Harbor Freight has a decent one for like 20 bucks.
       

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