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Thread: Timing and fuel trim

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  1. #1
    Join Date
    May 2009
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    Plainfield, IL
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    Timing and fuel trim

    My tune hasn't been getting the gas mileage my handheld used to. I emailed nelson and he told me to check the timing/fuel trim. I have no idea what "good" values are. What do ya'll think?




    Alright, at idle, timing is about 20* ltrim is about 4.6

    At cruising speeds (didn't change much between 50 and 70) timing bounces between 28 and 40*, seems to display 34.5 more then any other number.

    At same cruising speeds, ltrim b1 was 6.2, ltrim b2 was 5.4

    Whenever WOT, ltrim b1 is 5.4, ltrim b2 is 6.2, and timing is usually between 21.5 and 24 (seems to change lil depending on rpm/ outside temp/etc)


    These numbers are all from my aeroforce interceptor.
    blown transmissions are about as useful as 97% of the guys on this forum

  2. #2
    Join Date
    May 2008
    Location
    Crowder, OK
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    ltrims seem high to me.

    1969 Chevy RCLB C10 350/TH400 SOLD
    2007 Chevy RCSB 4.8 4x4 LS SOLD
    2008 Chevy RCSB 5.3 4x4 LT SOLD
    2010 Chevy CCSB 6.2 4x4 LT SOLD
    2005 GMC CCLB DRW 6.6 Duramax 4x4 191,000 and counting
    2013 FORD CCSB F350 6.7 Powerstroke 4x4


  3. #3
    Join Date
    May 2009
    Location
    Plainfield, IL
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    is that a simple tuning thing? or is it possible something else is wrong (though I doubt it, gas mileage seemed to drop pretty much overnight...well after a week when I finally stopped flooring it all the time lol)
    blown transmissions are about as useful as 97% of the guys on this forum

  4. #4
    Join Date
    May 2008
    Location
    Crowder, OK
    Posts
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    It's a tuning issue. What does your AFR look like?

    1969 Chevy RCLB C10 350/TH400 SOLD
    2007 Chevy RCSB 4.8 4x4 LS SOLD
    2008 Chevy RCSB 5.3 4x4 LT SOLD
    2010 Chevy CCSB 6.2 4x4 LT SOLD
    2005 GMC CCLB DRW 6.6 Duramax 4x4 191,000 and counting
    2013 FORD CCSB F350 6.7 Powerstroke 4x4


  5. #5
    Join Date
    May 2009
    Location
    Plainfield, IL
    Posts
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    don't have the wideband yet


    The aeroforce has o2 readouts, but those go all over the place. I have a autometer narrowband gauge, tempted to hook it up to the front 02s until I can afford the wideband (didn't think i'd need it until the cam/heads go in)
    blown transmissions are about as useful as 97% of the guys on this forum

  6. #6
    Join Date
    May 2008
    Location
    Crowder, OK
    Posts
    8,005
    I'd have a look at your AFR when you can.

    1969 Chevy RCLB C10 350/TH400 SOLD
    2007 Chevy RCSB 4.8 4x4 LS SOLD
    2008 Chevy RCSB 5.3 4x4 LT SOLD
    2010 Chevy CCSB 6.2 4x4 LT SOLD
    2005 GMC CCLB DRW 6.6 Duramax 4x4 191,000 and counting
    2013 FORD CCSB F350 6.7 Powerstroke 4x4


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