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Thread: Can someone read log to determine bad fuel mileage?

  1. 03-02-2016 #1
    85camarojunkie
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    Can someone read log to determine bad fuel mileage?

    Hey all, I was looking to see if someone could help with a fuel mileage issue I'm having. Trying to figure it out so I can tune it for my supercharger. I went from 20 mpg 3 yrs ago to about 12.5 to 13 today. I get 230 a tank. Can someone read a log file and possibly help me out?
    No CEL to go by. at i think 8:50 i have +8 or 10 knock and im not sure if that hurt anything but a 12min log file is included and it was some soft driving and several hard throttles which i typically do not do. Any thoughts would be appreciated. Changed 02 sensors, fuel pressure at idle is 50 psi, running 55, all cylinders compression test at 155-160psi, no pulleys tight causing drag.
    My rear end felt like it was dragging, one of the wheels was somewhat tight so i checked my diff fluid and it was black so i changed the oil and the magnet had a lot of real fine metal almost like anti seize, so im not sure if it is from discs in the limited slip or bearing failure?
    ANY more questions i can answered id live to have some help

    .2006 HARD RUN.hpl

    truck is a 2006 Chevy Silverado 1500 5.3 4wd auto
    Last edited by 85camarojunkie; 03-02-2016 at 05:14 PM. Reason: add log file
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  2. 03-03-2016 #2
    85camarojunkie
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    heres a cruise with a few hard stomps in oer drive and drive but 65-70mph

    cruise.hpl
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  3. 03-03-2016 #3
    5FDP
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    In that first log, at around the time mark of like 10:53.04 or very close, your o2 sensors both drop to nearlly nothing for almost a whole minute straight while you are cruising along at 53-55mph or so. That's not really normal.

    The second log is showing a maxxed out LTFT, they are always +10 or even +16 all the time. Possible big vacuum leak or your MAF sensor is at fault if the intake tubing is still all stock.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.
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  4. 03-04-2016 #4
    85camarojunkie
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    The intake tubing is all stock yes. Truck is bone stock factory settings. No mods. Weird the fuel trims are maxed I cleared them before log also. Any ideas? I can't fnd intake leak. Or vacuum leak. I've sprayed all over truck with 2 cans probably 3 times now.
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  5. 03-05-2016 #5
    CatnipG5Bandit
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    Try cleaning the MAF with MAF cleaner?
    2008 Pontiac G5 2.2L (main oil seal became a crunchy Autumn leaf, RIP)
    2016 Fiesta 1.0L Ecoboost - Project "not-so-detestable"
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  6. 03-05-2016 #6
    85camarojunkie
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    yes twice this year, a full can each time
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  7. 03-05-2016 #7
    85camarojunkie
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    posting these for another member thats been looking.

    truck 2 file is my truck i text you about and the van file is the van with a 6.0 i was telling you for referance.
    Attached Files Attached Files
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  8. 03-06-2016 #8
    Darth_V8r
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    Just replying so you know I looked. Your LTFT's are insanely high. looking through the log now and comparing to my 2004 suburban. Looking at injector pulse widths in particular. No surprise, but keeping the thread alive.

    In comparing my stock 2004 5.3L suburban with your stock 2005 5.3L Silverado, the main thing I see is your injector pulse widths are significantly higher than mine. Texted a couple screenshots to show you. Especially under high load, you're pulse widths are 30% higher than mine, with a longer injector duty cycle, and the computer is still trying to add more fuel with LTFT maxed out and STFT going high positive as well.

    Also, as you noted, you are over 85% duty cycle at 4500 rpm. it really seems like you just aren't getting fuel
    Last edited by Darth_V8r; 03-07-2016 at 11:48 AM. Reason: Added second, third paragraph
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  9. 03-07-2016 #9
    85camarojunkie
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    heres a very short log with maf unplugged my fuel trims dont seem as high, but knock is ridiculous

    no maf.hpl
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  10. 03-08-2016 #10
    85camarojunkie
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    easy ride no HARD throttleeasy.hpl

    back up of my ecm 06 pick up.hpt
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  11. 03-08-2016 #11
    85camarojunkie
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    heres the one with the Power Enrich mode addedenrichmode.hpl
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  12. 03-09-2016 #12
    85camarojunkie
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    after Mass Air Flow Calibrationmaf cal.hpl
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  13. 03-09-2016 #13
    GHuggins
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    If this is truly all stock, then put the tune back to stock until you find your problem. Will help things go more smoothly. With fuel trims out that bad... Have you replaced your fuel filter - don't remember if the 06's have one or not? Have you smoked tested the intake system? Finally if all that's good remove your fuel rails and injectors and tap them onto a clean white towel upside down after spraying a light amount of cleaner into them - don't know what your ethanol percentage is where your at, but it will turn your fuel system to sludge Everything I'm hearing is pointing to fuel restriction... 55psi with engine running isn't that great, but it is right in the "considered" specification of 55 to 62psi range. I preferred them around 58 to 60psi...

    Just some thoughts....
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

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  14. 03-10-2016 #14
    85camarojunkie
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    sorry i was posting these logs for another member here whos been helping. the fuel pressure gauge i was using was leaking a bit. I used a new gauge and its 55psi idle and 60 running, and holds 60 under load to, (i put gauge in the windshield driving)
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  15. 03-10-2016 #15
    85camarojunkie
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    HighToLow Octane.hpl

    all mods Low octane stock.hpl
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  16. 03-11-2016 #16
    Darth_V8r
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    bigdogstock.hptHere is a bone stock 2004 suburban 5.3L for you to compare
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  17. 03-12-2016 #17
    85camarojunkie
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    Heres a stock tune with new maf

    STOCK TUNE NEW MAF.hpl
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  18. 03-13-2016 #18
    85camarojunkie
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    New MAF with disable set to 100

    new maf no rpm.hpl
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  19. 03-13-2016 #19
    Darth_V8r
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    bigdog_dummy.hpt

    Here is a dummy tune using my 04 suburban. Just copy these maf values into your. this is based on your last log of the new maf in maf-only mode and the stock tune file. Should bring your fuel trims to very close to zero. open the file, copy the MAF vs frequency table, paste the values into your maf vs frequency table.

    Then, put your dynamic airflow back to 4000
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  20. 03-14-2016 #20
    85camarojunkie
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    new maf and freq.hpl

    loaded this file and i had no power at 2k, i was even pushing throttle 20% more. i do believe it was at 55% throttle.
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