Fuel Cut

Discussion in 'ScanGauge' started by visionseeming, Sep 15, 2008.

  1. visionseeming

    visionseeming Well-Known Member

    The setting for fuel cut determines at what TPS when the system is in open loop that it will assume the car is DFCOing right? For example, if you have it set to 24, whenever the TPS is below 24, and the car is in open loop, it will display 9999 instantaneous MPG right? That being the case, how does it differentiate from when the car is in open loop because it isn't warm yet? If idle is like 20, the car would be in open loop while warming up, and the SG-II will think it is DFCOing? How do you avoid this problem?:confused:
     
  2. abcdpeterson

    abcdpeterson Well-Known Member

    My warm idle is 16, cold idle is someplace between 18 and 21. I set the to 17, so it should not show DFCO if cold, as the idle tps will be to high when cold.

    I have been watching for just that when cold. I think I have seen a miss read DFCO once.

    when SG was set to the default 24, I know DFCO was being displayed when it was not in DFCO.
     
  3. visionseeming

    visionseeming Well-Known Member

    In your vehicle, what is the actual TPS during DFCO? Is it equal to idle? Is there any advantage to setting the cutoff above idle?
     
  4. abcdpeterson

    abcdpeterson Well-Known Member

    When I set it to 17 I was following someone else’s advice.
    I wish I could remember who it was to give them credit. But anyway.

    They said to start with the TPS low, moving it up one number at a time and check if SG was reading open loop and 9999 at the same time.
    With a warm engine that is just what I did. Started at 12 and kept working it up until cutoff and 9999 both happened at the same time.

    Before that advice I was just poking around trying different numbers. I could not find the correct setting by guessing.

    Note: Now that it’s reading correctly DFCO is something I look to a LOT to improve FE.

    did that answer your question?
     
  5. visionseeming

    visionseeming Well-Known Member

    Ah, okay, thanks. But have you observed at what TPS dfco actually occurs? Is it constant, or does it change depending on the situation?
     
  6. abcdpeterson

    abcdpeterson Well-Known Member

    I get DFCO at 17.

    as for constant... I think so, but let me explain.
    Never had DFCO above 17
    I have gotten to the point I can feel when the car goes into DFCO. I have never felt the car go into DFCO above 17.
    I could be mistaken but I think when the car is in DFCO I have also seen the TPS as low at 15.

    so
    TPS of 18 and above with open loop = cold engine = no DFCO
    TPS of 17 and below with open loop = warm engine = DFCO working.

    So, is 17 and below a constant? it's a constant point where DFCO starts happening.

    Hope that help.
     
  7. visionseeming

    visionseeming Well-Known Member

    Ah, okay got it, thanks! I see that you have a manual, its so much easier to DFCO in a manual. I'm stuck with an AT and can barely figure out what the hell the torque converter is doing half the time XD.
     
  8. Showbizk

    Showbizk Well-Known Member

    Just to jump in, I set my cutoff at 14 since the idle is at 10, and the Scangauge manual suggests idle + 4. With the manual, I achieve 9999 only coasting in gear. If I NICE-on, mileage is around 160, so I'm presuming no DFCO in NICE-on. The other checks--closed vs open loop seem to jibe.
     
    Last edited: Sep 18, 2008
  9. kuhl

    kuhl Member

    Re: Fuel Cut LP "open"

    Review of TPS Cutoff Property settings.
    "0" TPS is 12 at idle but at highway driving, it can be ~ 15 @ 3,000 rpm. Therefore it is necessary to have a higher cut nevau instance, some 16, it should probably not be much higher since it can result in an error at very low accelerator pressure ie. <16 TPS

    "translated by google"
     
  10. kuhl

    kuhl Member

    Review 2:
    scangauge count only fuel cut when TPS <"setting" AND LP Open (Open loop due to engine havy load OR fuel cut due to desacceleration)


    so sangauge default value 24 is not so bad
     
  11. Shrek

    Shrek Kaizen Driver

    A true hypermiler would start driving the car no more than some seconds after starting, and thus this would not be a problem anyway in real-world situations :) (The trottle would not be idle, that is)
     
  12. Shrek

    Shrek Kaizen Driver

    Re: Fuel Cut LP "open"

    Many toyota engines has an air bleed valve in addition to the throttle. Thus the throttle position (TPS) is not changed even tough the rpm can be 2x the idle rpm in situations as you describe.
     
  13. kuhl

    kuhl Member

    I really do not think TPS is a position, but a target for air intake (A / C gives more Bleed valve)
    Higher revolutions provides greater vacum
    and Scangauge writes TPS 18! @ 4000rev
    I have therefore set the TPS up to 18
     
  14. Shrek

    Shrek Kaizen Driver

    At least in my 'old' car with a cable from the pedal to the trottle, I can
    stop the car and play with the pedal, to see that the TPS value is changing
    in accordance with the pedal.

    For a drive-by-wire car, or a diesel car this might be different.
     
  15. kuhl

    kuhl Member

    If scangauge shows MAP and TPS (30 - 12) I turn off the engine but retains the ignition on and max accelerator as MAP will be updated but not TPS (101 - 12)
    My car is a Peogeot 107 (triplets) with eps = Egas

    I have no more problems with TPS cut 18
    but with TPS cut = 12 Scangauge will calculate consumption by desacceleration
     
    Last edited: Oct 8, 2008
  16. jdhog

    jdhog Hyper Smiler

    I set mine at 19 it seems to be about right. Mostly without my foot off the pedal it reads 15. I get the loop open and 9999mpg when I let off the gas and coast in gear. Just got the SG yesterday so I don't really know what I'm doing but enjoying it nonetheless
     
    Last edited: Oct 26, 2008

Share This Page