need help solving lean condition

Discussion in 'Engine & Drivetrain' started by HACK BLOCK, Mar 7, 2018.

  1. HACK BLOCK

    HACK BLOCK Full Access Member

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    i'm trying to get to the bottom of my super bad mpg (150-180 a tank) and p0171 and p0174 codes. at first i took it to a shop to be looked at and i was told i had 3 bad injectors and they wanted to charge me around $750 for 8 injectors and labor. but after changing my evap purge valve my check engine light went away and i figured they was trying to fuck me over. i ended up buying an al619 scan tool to figure out why my abs light was on and noticed my LTFTs were super high between 18% and 25%. after some reading online i came to the conclusion that i have a fuel delivery problem. but something i did notice is that my LTFTs are less than 10% when cold and rise has the car gets closer to operating temps. i have not checked my plugs yet and what should i check before i start dumping money into it
     
  2. swathdiver

    swathdiver Full Access Member

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    Vacuum leaks and your PCV system. Can you test each injector and coil with your scan tool? How old are your O2 sensors?
     
  3. HACK BLOCK

    HACK BLOCK Full Access Member

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    from what I read online I don't have a vacuum leak because if my LTFT got better when I raised the rpm then that would indicate a vacuum leak but mine pretty much stays the same no matter the rpm. I don't think I'm able to test the injectors with my scan tool and I bought the truck about 2 months ago so as far as I know it's original
     
  4. HACK BLOCK

    HACK BLOCK Full Access Member

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  5. Scottydoggs

    Scottydoggs Full Access Member

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    sounds like a large vac leak to me. spray the top of the engine down with carb cleaner, if the idle jumps up you found the leak area.

    when cold they run richer so it adds fuel to make it run at that higher idle till it warms up some. once the idle drops the trims go back to normal. in your case real high. thats gonna hurt your mpg too.
     
  6. HACK BLOCK

    HACK BLOCK Full Access Member

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    I'll check but like is said before I don't think it's a vacuum leak cause my fuel trim doesn't change when i Rev it and my car idles steady at around 550rpm.
     
  7. Scottydoggs

    Scottydoggs Full Access Member

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    if it stays pegged @+16 or higher, you have a vac leak.

    ltft should move when you give it gas. scan for codes, you might have a pending lean code. drive it for a bit, then scan it running, turning it off can clear a pending code.
     
  8. iamdub

    iamdub Content may not be suitable for all audiences

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    What do you mean by "as the car gets closer to operating temps"? You mean the LTFTs are low after a cold start? This particular point may not even be a consideration since the PCM is operating in open loop prior to operating temp. Then again, maybe it could help to diagnose the cause since the PCM is ignoring many sensor inputs during open loop. As it transitions to closed loop, it begins reading and responding to the input of those sensors. Check out a live data stream.
     
  9. HACK BLOCK

    HACK BLOCK Full Access Member

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    when the car is cold the fuel trims are normal but as the car warms up the fuel trims get higher and higher. when cold. both trims are less than 5%, but the time the temp is around 195 the trims are anywhere between 18% and 25%. the screen shots below are what I've been going by when deciding if it's a vacuum or fuel problem

    Screenshot_20180308-085855.png Screenshot_20180308-085904.png Screenshot_20180308-085916.png
     
  10. Scottydoggs

    Scottydoggs Full Access Member

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    all i know is a pegged ltft of +16 is a vac leak 100% of the time.

    can you scan bank one and bank two ltft's with the scanner you have? that would narrow it down to what side is having a issue.
     

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