P0174 Code At Idle

Discussion in '1996 - 2004 SN95 Mustang -General/Talk-' started by justadodgeman, Apr 22, 2014.


  1. justadodgeman

    justadodgeman Member

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    I don't have freeze frame data to prove it but I can drive it around for a while after clearing the code then when I shut it off and turn it back on the code pops up after a minute. so that tells me its a vacuum leak and not a fuel delivery problem cause it only affects the car at idle(idles a little rough but barely noticeable) so the egr valve when I did the smoke test barely leaked but I would think that would cause a p0171 and p0174 code correct me if im wrong. ive checked everything but that's the only problem ive found
     
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  2. justadodgeman

    justadodgeman Member

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    stock 96 mustang gt btw
     
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  3. COramprat

    COramprat Drone Driver
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    I've had a slight exhaust leak that through a code at idle.
     
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  4. justadodgeman

    justadodgeman Member

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    ive checked but ill check again. is there any better way beside feeling and listening for exhaust leaks
     
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  5. justadodgeman

    justadodgeman Member

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    alright so after advanced auto denying that their scanners did live readings a until I showed them on their website that they do they finally helped me out haha the long term fuel trim for bank 1 was fine but for bank 2 it was at 25% and didn't get any better till about 3500 rpms so that's telling me its a vacuum or exhaust leak right?
     
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  6. tb9050lx

    tb9050lx Member

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    p0174 bank 2 lean . check for leaks in the pcv system , ck the valve , also things like intake gaskets can cause leaks , depending on the bank a plugged fuel filter can also cause a lean code on one bank , as can the evap system . egr valve would most likely effect both banks.
     
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  7. justadodgeman

    justadodgeman Member

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    If it was a fuel delivery problem Im pretty sure the ltft would have gotten worse at higher rpms so I think that rules out fuel filter but im gonna get a propane torch tomorrow and see if I can find leaks anywhere. I have just replace the pcv valve and ta is on bank 1 but how would I check it anyways? I know nothing about the evap system but where would that leak from? tell me if this makes sense please-if the egr valve is stuck open and the tube from it goes to the bank 2 manifold therefore it is sucking exhaust out and making the o2 sensor think there is an exhaust leak making it run lean?
     
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  8. tb9050lx

    tb9050lx Member

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    if the egr valve was staying open the engine would run slightly rough at idle and most likely lodge a p0401 or p0402 , the best way to look for leaks is with a scan tool capable of real time data and some carb spray ,while monitoring , the short and long term fuel trims spray the carb spray around the gaskets , hoses , valves and such , if the short term fuel trim drops that area is most likely the leak .
     
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  9. tb9050lx

    tb9050lx Member

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  10. justadodgeman

    justadodgeman Member

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    ok the valve stays open a little bit cause only a little smoke leaked through but it not enough to throw a code I guess
    I don't have a scanner but I tried propane and carb cleaner and found no leaks, fuel filter is brand new and so is pcv valve but how would the pcv valve cause a lean code? im wondering cause id like to check it out and make sure I didn't get a defective one.
     
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