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Thread: L.t.f.t closer to 0 affect gas milage?

  1. #1
    Lifetime Member smslyguy's Avatar
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    Default L.t.f.t closer to 0 affect gas milage?

    can your L.T.F.T. closer to 0 give you better fuel econonmy? I mean if you L.T.F.T. are at say 20% and you get them closer to 0 would you see improved fuel econonmy?
    2001 camaro z28 ss vert with factory slp upgrades, Hooker long tubes, 3"y-pipe to a 4" muffler, ,airlid,s.s.r.a. ,t.c.bypass,descreened m.a.f. 232/234 .595,.598 +2 comp cam with ported and polished stock heads with .650 lift dual springs and a bowl grind. tuned with EFI Live. All combined to achieve 29 m.p.g. and 399 r.w.h.p. with 384 lbs of torque. sold...

    Now own a 2015 1LE camaro

  2. #2
    Lifetime Member mr.prick's Avatar
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    Are your LTFTs 20%, or is this a hypothetical question?
    High LTFTs cause AFR to be whacked.
    The easiest way to find out is to log WBO2 and see how BENs are in CL.
    For me, BENs are between .99 to 1.02 with LTFTs averaging -2%,
    being a little lean from idle to 1200 RPM.

    LTFTs that high could be an intake or exhaust leak.
    512k RoadRunner Firmware 12.14R
    FlashScan V2 Bootblock V2.07.04 Firmware V2.07.22 EFILive V7.5.7 (Build 191) V8.2.1 (Build 181)
    LC-1 WBO2

    _________________________________________________

  3. #3
    Lifetime Member smslyguy's Avatar
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    Quote Originally Posted by mr.prick View Post
    Are your LTFTs 20%, or is this a hypothetical question?
    High LTFTs cause AFR to be whacked.
    The easiest way to find out is to log WBO2 and see how BENs are in CL.
    For me, BENs are between .99 to 1.02 with LTFTs averaging -2%,
    being a little lean from idle to 1200 RPM.

    LTFTs that high could be an intake or exhaust leak.
    yes my 2000 gmc the ltft are that high. I wil have to check and see if i do have an intake leak, although if i had it should be ideling higher than normal, which it's not. and no to the exhuast leak.
    2001 camaro z28 ss vert with factory slp upgrades, Hooker long tubes, 3"y-pipe to a 4" muffler, ,airlid,s.s.r.a. ,t.c.bypass,descreened m.a.f. 232/234 .595,.598 +2 comp cam with ported and polished stock heads with .650 lift dual springs and a bowl grind. tuned with EFI Live. All combined to achieve 29 m.p.g. and 399 r.w.h.p. with 384 lbs of torque. sold...

    Now own a 2015 1LE camaro

  4. #4
    Lifetime Member smslyguy's Avatar
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    just check for an intake leak and it turned out negative, there is not a intake leak. The truck runs fine no hesatation or stalling just the ltft are around 20% here is a scan i ran
    Attached Files Attached Files
    2001 camaro z28 ss vert with factory slp upgrades, Hooker long tubes, 3"y-pipe to a 4" muffler, ,airlid,s.s.r.a. ,t.c.bypass,descreened m.a.f. 232/234 .595,.598 +2 comp cam with ported and polished stock heads with .650 lift dual springs and a bowl grind. tuned with EFI Live. All combined to achieve 29 m.p.g. and 399 r.w.h.p. with 384 lbs of torque. sold...

    Now own a 2015 1LE camaro

  5. #5
    Lifetime Member mr.prick's Avatar
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    Any mods to the truck?
    I don't know if it is normal for a truck to have high LTFTs but
    it would go against common lore of having LTFTs 0% or slightly negative.
    512k RoadRunner Firmware 12.14R
    FlashScan V2 Bootblock V2.07.04 Firmware V2.07.22 EFILive V7.5.7 (Build 191) V8.2.1 (Build 181)
    LC-1 WBO2

    _________________________________________________

  6. #6
    Lifetime Member 98 tigershark's Avatar
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    I had just worked on a 2000 Camaro that had those type of LTFT's and it was an exhaust leak that looked very small but caused the trims to be out of wack. An exhaust leak is not as easy to find sometimes.
    98 tigershark
    98 tigershark
    L92/427 w/L76 CC'ed heads n upgraded springs
    4.100 stroke, 4.068 bore w/ 11:1 comp
    Cam, 591 int, 613exhst, 232-246dur@.050, 115*
    LG headers, High flow cats,
    RPM level 5 trans, RPM 3.42 gears, 2800 rpm trq convrt. .
    Special Thanx to Joe and Bruce!

  7. #7
    Lifetime Member smslyguy's Avatar
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    Quote Originally Posted by mr.prick View Post
    Any mods to the truck?
    I don't know if it is normal for a truck to have high LTFTs but
    it would go against common lore of having LTFTs 0% or slightly negative.
    no mods at all it is a stock 5.3 truck
    2001 camaro z28 ss vert with factory slp upgrades, Hooker long tubes, 3"y-pipe to a 4" muffler, ,airlid,s.s.r.a. ,t.c.bypass,descreened m.a.f. 232/234 .595,.598 +2 comp cam with ported and polished stock heads with .650 lift dual springs and a bowl grind. tuned with EFI Live. All combined to achieve 29 m.p.g. and 399 r.w.h.p. with 384 lbs of torque. sold...

    Now own a 2015 1LE camaro

  8. #8
    Lifetime Member smslyguy's Avatar
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    Quote Originally Posted by 98 tigershark View Post
    I had just worked on a 2000 Camaro that had those type of LTFT's and it was an exhaust leak that looked very small but caused the trims to be out of wack. An exhaust leak is not as easy to find sometimes.
    98 tigershark
    no exhuast leak either. I do however, have a code po452 (fuel tank pressure sensor condition. don't know if this is related to the ltft or not??
    2001 camaro z28 ss vert with factory slp upgrades, Hooker long tubes, 3"y-pipe to a 4" muffler, ,airlid,s.s.r.a. ,t.c.bypass,descreened m.a.f. 232/234 .595,.598 +2 comp cam with ported and polished stock heads with .650 lift dual springs and a bowl grind. tuned with EFI Live. All combined to achieve 29 m.p.g. and 399 r.w.h.p. with 384 lbs of torque. sold...

    Now own a 2015 1LE camaro

  9. #9
    Lifetime Member 98 tigershark's Avatar
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    Default P0452 Is usually an EPA OBDII issue, I think?

    That could affect the LTFT and STFT as they are both OBDII issues.
    I have heard of that before. Do you know what to do to fix the problem. It could be a bad sensor or even a bad fuel cap. It is hard to tell but again I have heard of this effecting the fuel trims but have not seen this personally.
    Regards,
    98 tigerhark
    98 tigershark
    L92/427 w/L76 CC'ed heads n upgraded springs
    4.100 stroke, 4.068 bore w/ 11:1 comp
    Cam, 591 int, 613exhst, 232-246dur@.050, 115*
    LG headers, High flow cats,
    RPM level 5 trans, RPM 3.42 gears, 2800 rpm trq convrt. .
    Special Thanx to Joe and Bruce!

  10. #10
    Lifetime Member smslyguy's Avatar
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    Quote Originally Posted by 98 tigershark View Post
    That could affect the LTFT and STFT as they are both OBDII issues.
    I have heard of that before. Do you know what to do to fix the problem. It could be a bad sensor or even a bad fuel cap. It is hard to tell but again I have heard of this effecting the fuel trims but have not seen this personally.
    Regards,
    98 tigerhark
    have you ever heard of this decreasing your fuel economy? Or does this not affect fuel economy? I beleive it is for fuel vapars, but i really can't see you loosing any m.p.g from your evap system?? No i don't really know the problem yet, but i am trying to figure it out.
    2001 camaro z28 ss vert with factory slp upgrades, Hooker long tubes, 3"y-pipe to a 4" muffler, ,airlid,s.s.r.a. ,t.c.bypass,descreened m.a.f. 232/234 .595,.598 +2 comp cam with ported and polished stock heads with .650 lift dual springs and a bowl grind. tuned with EFI Live. All combined to achieve 29 m.p.g. and 399 r.w.h.p. with 384 lbs of torque. sold...

    Now own a 2015 1LE camaro

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