rhin0sb

Greetings,

I've got a pretty much stock stick xb, stock wheels, and stock suspension, the ony thing i've changed was my spark plugs and added a cold air intake.

I recently calibrated my speedo with a GPS system to find that my speedo was 3% off.

1) do most of you who've calibrated your speedos found that it was only 3% off?

2) after calibrating, i've found the scanguage miles per tank is way different than what my odometer is reading. which one is correct?

3) also when filling up, i notice the scan guage never can tell how much gas i actually put in (i always have to adjust that), did i set up my fuel tank right. It's set to 1.5L, and 12Gal (I know the xB has a tank listed at 11.9 Gal)

4) which mpg do i trust, mine calculated by the miles on my speedo and how much gas i pump at the tank, or the miles on the scan guage speedo and how much gas i pump, or the mpg listed on the scan guage?

just curious

IH8ONYU

the spedo is off by 3%, due to the japanese bb running a different tire size, the odo is off the other way - if you cal your spedo to be exact your odo is off... thats just one quirk our cars have.
miles per tank will take a few tanks worth of gas to let the SG calculate and catch up, after 3 tanks, mine was pretty right on, still off by a hair though, it's normal.
also, the xb has a 9.9 gal tank, thats why you are off.
set it to 10 gal...
best way to set up your spedo is by GPS or by counting mile markers at 60mph for 10 miles.
just know it is exactly 3% faster then reality

1epoXyBox

???

douglasinct

Excuse me for pointing this out, but you are quoting IMPERIAL GALLONS - which uses 20 fl oz. to the pint.

The U.S. equivalent, as per the Owner's Manual, is 11.9 US. gallons. This system uses 16 fl. oz. to the pint.

IH8ONYU

aha, i stand corrected.
i have always used 10 gal on my scanguage, and it is always (after 3 fillups) within 1 10th of a gal correct..

mijos87

good info so which is it? 10 or 12?

peteski

11.9 US Gallons

douglasinct

For ANYONE living in the USA the answer is 11.9, which rounds up to 12. :D

Jan06xB

If you set the SG to less than the capacity of the tank it will stop counting after it reaches the limit - however setting it to 12 gallons will indicate you have a little more gas left in the tank than you actually have so don't try to run it all the way down! Usually a 0.1 gallon variation in the fillup is normal IF you consistantly fill it all the way up. 3% speed error is about right and you should be traveling a little further than the odometer indicates meaning that you are getting better MPG than calculated by the Odometer in the xB dash.

rhin0sb

Thanks for some of the clarification guys, but if Jan0xB is correct, should I be using the odometer reading of the ScanGuage and then dividing that by the gallons pumped to figure out an accurate MPG?

thanks again

Jan06xB

YUP that's what I do and all the guys that are getting the 500+ miles on a tank of gas also apply that correction factor. One nice thing about the odometer reading low is that your warrenty last a little bit longer.

typhoonorchid

I though part of the point of getting a SG was the real time feed back of your MPG, or a trip average. Not just waiting till your tank is finished. how far off is the SG from from the correct figure, in both instantaneous and tank average?

Jan06xB

The accuracy of the instant readout is a function of the fillup calibration that compensates for the estimate of the fuel being injected in each pulse that it counts. Initial setting can be about half a gallon off from actual which in a 10 gallon fillup is 5% error. The newer ScanGauge does a much better job of measuring actual fuel used because it compensates for the fuel cutoff during engine braking which the earlier software, like the one I have, didn't calculate. As a result I get some variation in the fillup amount because mine still has the engine burning fuel during engine braking which over a 10 gallon tank can be almost half a gallon. Calibrating the speed properly also affects how far you are traveling in miles (the speed adjustment corrects the odometer error) which also directly affects the mileage calculation.

douglasinct

Excellent point.

Also NEVER run a tank lower that 1/4 full... unless you want to prematurely burn out the fuel pump and to pay for the repair ($$$) - BTDT.

Why?
Because:
- The fuel pump is located INSIDE the fuel tank.
AND
- The fuel pump NEEDS gasoline around it to keep it cool.

kewlbox

I have run every car that i have under empty all the time, and never had i had to replace a fuel pump ever.

douglasinct

You, Sir, are most fortunate.

However, I still stand by my original statement.

Jan06xB

Actually I believe the fuel pump is located in the tank on top and uses gasoline running through it to cool it so keeping enough gas in the tank to prevent sucking air into the pump is all that is needed. I have referred to the fuel system diagram that used to be on line here in SL.

douglasinct

I defer to your knowledge of the vehicle.

I am a relic from older American fuel systems.

Jan06xB

Of course the other thing to remember is that the xB does NOT return excess fuel to the tank via a regulator in the engine compartment so any air you suck into the fuel system from the tank while stopping turning going up or down hills or accelerating with a nearly empty tank will end up pumping air into the injectors and causing some misfires and hammering of the components and in-line filter with fuel surges. The most important thing to remember is that when you finally do run completely out of gas, make sure you turn off the ignition or else you will be running the fuel pump . . . dry.

rhin0sb

so i read in some other thread, that somebody set their offset at 14. all i know about the offset is that its something to do with throttle position and when fuel stops getting pumped in.

anybody else, set this offset thing up?