Another trip with a useless Scangauge

Discussion in 'ScanGauge' started by jambo101, Apr 2, 2014.

  1. jambo101

    jambo101 Active Member

    The MPG on my Scangauge is useless as it seems to change everytime i fill the tank.
    I use an X gauge to give me an average read out for the day, after setting all parameters,filling the tank and pressing done the next fillup seems to be way off,adjusting the fill up to what i just put in the tank throws MPG numbers way off,
    What could i be doing wrong?
  2. No Static At All

    No Static At All Active Member

    Do you leave the SCII in the car all the time, or take it out at night? Also, do the other non X-Gauge MPG readouts provide fairly accurate/consistent numbers?

    FWIW, the "Today" reading on mine does not seem to reset correctly if I ever disconnect the unit between fills. It only works right if always connected & never removed from the car. Otherwise all else is accurate.
  3. ALS

    ALS Super Moderator Staff Member

    Normally it take four or five fill ups to get it close to your actual fill. I'd go back and run through the setup operation again making sure all the inputs are correct. If one item is off it could throw everything out of kilter as they say.
  4. Die2self

    Die2self Saving more by using less!

    you may want to also, try only adjusting the gals input to 1/2 of what the change was. Some have had the same issue as you when putting the exact number of the gal's filled. If this way off of what the SG showed as it used, then the roller coaster ride will start with the next fill up and the numbers will progressively get more out of whack.


    SG shows you used 10.65 Gals
    The pump shows you put in 10.95 gals

    at the fill up screen instead of putting in 10.95 I would 1/2 that number and put in 10.80 gals. This will take a few tanks to actually narrow down to a more consistent reading, but it will help. However, there a lot of factors that can throw this off as well.

    Your Drive style (if you FAS P&G alot)
    Winter/summer blend switch
  5. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Linear Logic has an interesting definition of the word "today". Nuff said.
  6. 08EscapeHybrid

    08EscapeHybrid Moderator

    The only way my Scangauge is accurate is if I go to the same station, same pump, facing the same direction, and stop fuelling at the first pump cutoff. Also, if I deviate from my regular mix of city/highway driving this will throw it off too. If my scanguage reports fuel used as different, I only input 1/2 the difference like Die2self mentioned. In the end, the scangauge is not measuring fuel entering the engine, but air entering the engine, and it tries to extrapolate the amount of fuel used based on that data. Best you can hope for is to be close.

    If the difference between the scangauge calculated usage and pump fill gallons is less than one gallon, I don't even bother messing with the offset. I just let it ride. Also, if one tank is off, but it was a significant deviation from my normal driving routine (more highway than normal, excessive mountain driving), or if the tank was on a type of fuel I don't normally use (different octane or if it contained ethanol) I don't correct it at all, even if its off by a couple gallons.
  7. 08EscapeHybrid

    08EscapeHybrid Moderator

    From the Scangauge website:
  8. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    For Edwin , "today" begins at midnight(12:01 AM) and ends 24 hours later at midnight.
    Those guys infuriate me !
  9. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Jambo:

    Following the rest, at each successive fill, you should see the offset growing smaller and smaller. If you are down to 2% or less in terms of gallons filled, your SG-II should read darn near real consumption.

    At each fill after you input the gallons filled, what kind of offset are you seeing?

  10. WriConsult

    WriConsult Super Moderator

    What others said: dial in the offset gradually. If you try to fully make up for the error each time you fill up, you'll end up vacillating wildly back and forth. When I'm first dialing it in, I only attempt to adjust out HALF of the discrepancy versus the pump each time. That usually dials it in within 2-4 tanks.

    I can live with the TODAY logic on the scangauge, since you always have the option to view PREV DAY.

    What drives me crazy is that there is no PREV TRIP option. If you return to the car after running in somewhere for a couple minutes, the CURR TRIP resets itself about half a second after you put in the key, and there is no way to get that data back.
  11. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I personally would like to see them store the last five , seven , even ten trips of each day. It can't be that difficult to do that , right ?
  12. No Static At All

    No Static At All Active Member

    . . .Or at least keeping the "Current" trip data unless manually reset.

    My unit has been unplugged for about a week, & will still display the "Today" info from last Sunday. It will not reset "Today" until filled up again in a week or so. Does this sound right?

    Hmm, wonder whatever happened to the OP??
  13. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    They could solve a lot of the trouble by making Today resettable. You can reset it at the start of running errands and end up with a total for the outing. If you're out late one night, you can reset in the morning and have an actual "today" reading.

    I've suggested this to them for years now.
  14. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    That would help immensely.
  15. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    One thing to remember is that even if the calibration is off, a 10% mpg improvement will still be an improvement at the pump. The base calibration is wrong, but the difference between A and B, by percent, will be the same.
  16. WriConsult

    WriConsult Super Moderator

    Well, that would be a nice-to-have, but the lack of a PREV TRIP, when CURRENT TRIP resets itself without warning, is a significant design deficiency.
  17. Fwiw - swapped back to factory sized tires earlier this month. ReCal'd the SG after one fill up.
    Todays fillup:
    the dash read 112.2 miles, 13.6 mpg, 8.2 gal, 25.8 mph avg
    The SG read 111 miles, 13.4 mpg, 8.2 gal, 25 mph

    Close enough for me. :)
  18. jcp123

    jcp123 Caliente!

    SG seemed to be more accurate than UG. It seemed a bit better for segments owing to it retaining some data vs. the UG just having current MPG and tank MPG. I found the SG a pretty good all arounder but I like the form factor and expanded live data capabilities of the UG better. And the UG has so far been far more reliable than my SG was.

    I can understand it being more inaccurate when deviating from your standard mix of driving - we all know that our own engines have different calibrations for different situations. With SG calculating an estimated mpg from the data it gets via the OBD 2, there's no way it can be in sync with the idiosyncrasies of every single vehicle out there.
  19. joesgot4

    joesgot4 Well-Known Member

    I changed from my green 2012 Hyundai accent to my black Hyundai accent and filled the car up the scan gauge said I added 102 gallons when I only added 8.7, I adjusted the scan gauge gallons to 8.7 which took ten minutes, ill see on next fill up if it's closer.
  20. jambo101

    jambo101 Active Member

    A belated thanks to all..:)

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