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LTFT is high except at idle and WOT

Discussion in '4 Cylinder' started by mytoy04, Jan 25, 2015.

  1. Jan 25, 2015 at 5:35 PM
    #1
    mytoy04

    mytoy04 [OP] Well-Known Member

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    Tim
    Liberty, MO
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    Ok I have a 4Runner with the 2.7 5sp 4x4. I got a scan tool for Christmas and have been studying fuel trims and how to use these readings for diagnosis. So what I've noticed on the scan gauge is my LTFT at idle is a solid 3.9. But as soon as I push on the accelerator they jump up to 14% while the STFT is right around 0 going between + and - 1-2%. I let off the accelerator and the long term drops right back to 3.9. And while on the highway I'd floor it and the LTFT would correct back to the 3.9%. Very weird I believe. So my research tells me that is a fuel delivery issue instead of a vacuum leak. Not sure how to check the fuel pressure cause there is no test port for my fuel pressure gauge. Also, no CEL and no codes stored. I've cleaned the MAF, and the o2 is fairly new as is the catalytic converter. Any guesses as to why that's new? Haha, jerk cat thieves. So, any help in the direction I should go would be great. Thanks.
    Oh yea, I did a smoke test to just rule out the vacuum leak and noticed smoke from the egr vacuum modulator, not the egr valve but the green modulator above it. Kinda suspicious of that, could that be the problem?
     
  2. Jan 25, 2015 at 6:23 PM
    #2
    vstrom

    vstrom Well-Known Member

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    Man I have no idea.. I'm just subbing onto this thread because I'm just starting to research fuel trims as well.

    Question though.. on the scangauge are you reading LTFT on just bank 1 or did you plug them all in? If you plugged them all in could it narrow down the problem?
     
  3. Jan 25, 2015 at 6:32 PM
    #3
    mytoy04

    mytoy04 [OP] Well-Known Member

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    Tim
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    Well my understanding is on 4cyls there is only one bank. Not sure about the scangauge you speak of. I have an Actron scan tool. On v6 and v8 motors you'll have banks 1&2. You mite be reading cylinders, so again not sure of the scangauge and what it reads.
     
  4. Feb 1, 2015 at 5:35 PM
    #4
    Speedytech7

    Speedytech7 Toyota Cult Ombudsman

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  5. Feb 11, 2015 at 5:33 AM
    #5
    mytoy04

    mytoy04 [OP] Well-Known Member

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    Speedytech7, funny you should mention ScannerDanner. That's exactly where I went and have watched several of his videos now. Good stuff for sure. Wish I could be in his classes.

    I wish I could ask him these questions. I posted this question on another forum and you wouldn't believe some of the responses. So I said all my info is from, ScannerDanner videos.

    On my 4R, it is so weird watching the fuel trim data. I let off the gas it drops to 3.9% and immediately when accelerating it jumps back up to 14+ LTFT. And according to ScannerDanner it should be around 0% +/- 5%. And its my understanding that this is gonna be from a fuel delivery issue. But on the other forum they are saying 14 is normal and no codes so don't worry about it.
    So I'd love to test my fuel pressure but the 2.7 doesn't have a test port. And I've not had anybody walk me through on how to check my fuel pressure (hint, hint) :)
     

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