ScanGauge II problems, issues and more problems!

Discussion in 'ScanGauge' started by Giffer2, Dec 20, 2008.

  1. Giffer2

    Giffer2 Active Member

    Bought myself a scangauge unit the other week, installed easily and simply enough setup as per the instructions -

    11 Gallon Tank
    1.7 Litre Engine
    Dieselb (As the test shows that the GPH doesn't move at all when set to a and the revs taken up to 1500)

    Fillups -

    1st as per instructions
    2nd - Had to add 90% to correct the under reading of the amount of fuel added
    3rd - Had to add 120% to correct the under reading!

    So I've reset it for the 3rd time and trying again!

    But I've noticed the following -

    Random power offs whilst driving, the unit will just power off - not flicker and go to sleep like it does after you switch the engine off, but actually power off! - At this same time it doesn't register the distance I have driven (I reset the car's trip odometer each time I fill up).

    MPG (Current tank) is off and just seems to be guessing figures (Hence the 3 resets).

    The MPG (Current trip) can reach 120MPG on steady 20mph driving (eg slow traffic) and sits at a nice 60 - 70mpg at 50-60mph, but jump on the motorway and it'll read around 40-45mpg at 70mph or even less with the cruise control on.

    Yesterday it read around 20mpg for a nice constant speed of 70mph (So yet again another reset today) over a 30 mile distance, then started to correct itself eventually.

    Something I am curious about though, how does the unit cope with UK gallons? I can understand the under reading when you add fuel, but the tank size shows 11 Gallons, but correct me if I'm wrong but these will be US gallons which means it's way off for me in the UK.

    Any help would be appreciated as this unit is annoying the hell out of me!
  2. SentraSE-R

    SentraSE-R Pishtaco

    It sounds to me like you have an intermittently bad power or data connection. I'd check the pins in the female RJ-45 connector, or plug your cable into the other connector of your SG, and see if you get a more solid connection.

    You can either convert UK gallons into US gallons, and v.v., or possibly make an xgauge to display mpg, and program the MTH function to convert the US mpg / .833 into miles/UK gallon for you.

    If you put 8.33 UK gallons into your fuel tank, you enter 10.0 US gallons into your SG for fill-up quantity. You mentally convert the result from US mpg to UK mpg.
  3. SentraSE-R

    SentraSE-R Pishtaco

    To elaborate on how to program an Xgauge to display current trip mileage in UK mpg, you'd edit a memory location with TXD 00 (where the first 0= avg mpg, and the second 0= current trip). RXD would be 8 followed by all 0s to tell the XG it's a trip gauge. The MTH would be to convert the US mpg into the UK by multiplying the results by 1000 and dividing by 833. The first 4 bytes are the multiplier, and 03E8 = 1000. The second four bytes are the divisor, and 0349 = 833. My math may be off, and I haven't actually tried it, but that should give you an idea of how it's done.

    To code it out for you, since not everyone thinks in hexadecimal, 03E8 = 1000 because the first 8 = 8 where the range is 00=0, 01=1, 02=2, 09=9, 0A=10, 0B=11, 0C=12, 0D=13, 0E=14, 0F=15. The second digit is the E, which represents 14 (E) X 16, or 224 (10=16, 20=32. 30=48 ... E0=224). The third digit represents 3 X 256, or 768. 03E8 = 768 + 224 + 8 = 1000.
  4. Giffer2

    Giffer2 Active Member

    I understand the Math section, makes perfect sense that I'd need to tell the unit about the difference - all the gauges I display are XGauges -

    (Current Trip MPG)(Current Tank Distance)
    (Current Tank MPG)(Current Tank Distance to Empty)

    But, what about the tank size, this is going to show 11 US Gallons, not 11 UK Gallons (My actual tank size is 53 Litres, which is 11.65 UK Gallons or approx. 13.98 US Gallons).

    I'd also guess that I'd need programme the math section to take the US MPG and multiply it by 1.2 (As the UK Gallon is 1.2 times larger than the US Gallon).

    So let me see if I'm correct in my logic here...........

    Set the tank size to show 14 US Gallons, edit my relevant XGauges to allow a multiplier of 1.2 to show the correct Trip MPG and Tank MPG.

    This to me sounds like a hell of an overkill to get it to work correctly - I might talk to my supplier as it sounds like the SG isn't suitable for the UK right out of the box.
  5. Giffer2

    Giffer2 Active Member

    I've had a brain wave!

    I've set the units to Litres (Liters on the unit) and programmed the correct tank size, so obviously now my units are in miles per litre - So, the math side of the XGauge should have a multiplier of 4.55 to show Miles Per UK Gallon and hey presto problem is solved!

    Next daft question, what is the value I need to add to the MTH side of the XGauge to add this 4.55 Multiplier?

    If I've done my sums right the math should show the following -


    Which would be

    x455 (01c7) /100 (0064) (To give an overall multiplier of 4.55)
    Last edited: Dec 21, 2008
  6. SentraSE-R

    SentraSE-R Pishtaco

    Good logic, Giffer2. I agree with your math, except you left one 0 off the end of your composite number. It should be 01c7 0064 0000, not 01c7 0064 000. Let me know how it works. I'm confident you've got it figured out correctly.
  7. Giffer2

    Giffer2 Active Member

    I've added the math side of things to the 2 xgauges but it didn't make any difference to the value displayed -, I did it whilst the engine was running so not sure it this makes any difference at all?

    For example below is the setting for my Current Trip Mpg XGauge

    TXD = 00
    RXF = 800000000000
    RXD = 0000
    MTH = 01C700640000
    Name = Mpg

    Which is average fuel economy on current trip, displayed as an Xgauge, with math of x455 and /100 and name of Mpg.

    But the display still shows the same value as the Trip gauge for that measurement. (eg in Miles per litre)
    Last edited: Dec 21, 2008
  8. SentraSE-R

    SentraSE-R Pishtaco

    Are you sure you're displaying the Xgauge MPG and not the default SG MPG? Try renaming your Xgauge mpg to something different, like UKM, and cycle to that display.
  9. Giffer2

    Giffer2 Active Member

    100% sure as the 2 XGauges are named
    Mpg (Lowercase pg) and Avg (Again lowercase vg) so I know that they are XGauges and not the standard gauges.

    I'll have a look tomorrow incase it was caused by me changing the details of the XGauge whilst displaying it and having the engine running and using fuel.
  10. SentraSE-R

    SentraSE-R Pishtaco

    You may need to cycle the factory MPG display out of sight. I've noticed if I inadvertently have two MPG displays showing, that only one of them displays numbers. Something similar may prevent the new Mpg or avg functions from doing their math correctly.

    Your initial results aren't encouraging. I wonder if we need to change the RXD value to expect something different from the standard trip gauge. It's also possible trip gauge data can't be altered, and you'd have to modify the actual original coding for the MPG gauge to get the results you want. I'll play around with it tomorrow if I have the time.
    Last edited: Dec 22, 2008
  11. SentraSE-R

    SentraSE-R Pishtaco

    There's a message in the SGII Xgauge Database thread that indicates the MTH figures are ignored. "On the RXF screen that will come up next make the first character an 8, this tells the ScanGauge that the gauge you are creating is to be used as a trip gauge. All values after the 8 are ignored. inclusive RXF and RXD and Mth ignored
    and even if you could, you can not get 1 / x"

    Here's another message relating to coding trip gauges. Again, it's not too encouraging.
    "Well... XGauge is really just a data linearization tool. The "math" is just used to scale units (ie convert degC to degF). You can report anything your car reports. So if your car/truck reports MPG or lhk over your ODBII port and IFF you know the ODBII / CAN pid for that data, you can get the data and use "MTH" to convert it to mpl. Unfortunately, I don't know how to make an XGauge off of one of the SGII's internal gauges (like MPG)."
  12. fuzzy

    fuzzy Mild hypermiler

    Due to lack of need on my part, I haven't get track of the programming details. But as for the difference between US vs UK gallons, would it be possible to "recalibrate" the SGII to UK gallons merely by setting a proportionately smaller displacement? For your engine, this would mean declaring 1.4 liters instead of the actual 1.7.

    For engines such as mine where fuel use is estimated from displacement, RPM, and manifold air pressure, it seems that this should work. For others that have an actual air mass flow sensor, this might not do the job.

    Any thoughts on this?
    PS. I'm was thinking of gasoline engines, not diesel.
    Last edited: Dec 22, 2008
  13. SentraSE-R

    SentraSE-R Pishtaco


    I coded an Xgauge for a UK current trip average display, and got identical results to yours. It's the standard current trip average mpg, ignoring the math figures we want to manipulate the results with. So, it looks like you'll have to find the trip average parameters and call them directly. Trip gauges apparently can't be manipulated.
  14. Giffer2

    Giffer2 Active Member

    I've spoken to my supplier who has said the following -

    The unit powering off is probably a loose connection - nothing we didn't already know!

    Apparently when you do the fillup, adding the correct amount of fuel used should set the unit to UK Gallons - Although I'm not convinced myself.
  15. SentraSE-R

    SentraSE-R Pishtaco

    I noticed the reference to Imperial gallons in the FAQs. The applicable Q&A are:
    Q. Does the ScanGauge II support metric units?
    A. Yes, the units of measure can be independently selected between Miles/Km, Gallons/Liters, Celcius/Fahrenheit, and PSI/KPA.

    If you choose Km and Liters, fuel economy is reported as liters/100Km (LHK).

    If you use Imperial Gallons when you do the calibration, fuel will then be adjusted to use Imperial Gallons.
  16. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    That makes sense as your fuel offset would simply be the conversion factor between US and UK gallons.
  17. Giffer2

    Giffer2 Active Member

    I've had the following email from linear-logic

    "The ScanGaugeII uses gallons as a unit label and not as a measuring unit. As a result, the ScanGaugeII's gallon setting can be both US and Imperial. As long as you keep all entries consistent (both tank size and the fill-up procedure) the calculations should match up just fine."

    So it's a case of getting the correct offset set on the unit - but of course thats going to be hard seeing as it switches itself off!
  18. Giffer2

    Giffer2 Active Member

    Just a quick update - I've had the unit back from the supplier who soak tested it and found nothing wrong..........but they replaced all the internal components just in case.

    But they forgot to send the cable back with the unit so I have a unit that is kinda useless at the moment! :)
  19. SentraSE-R

    SentraSE-R Pishtaco

    Thanks for the update. Hopefully you'll have your unit functioning soon.

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