Scangauge II accuracy

Neous

Veteran Member
Joined
Jan 17, 2007
Location
Woodstock, CT
TDI
2009 Audi Q7
this is my first fill so I don't expect tank accuracy to be correct but while my speedometer shows that I'm doing 70 mph the scangauge show that I'm doing 66 mph
 

roadhard1960

Veteran Member
Joined
Feb 1, 2004
Location
Covington, Ga.
TDI
2003 Jetta wagon GLS 5 speed
What does your GPS show? On the highway drive exactly 64 mph on a level area with mile markers and the cruise control turned on. Start timing between mile markers. If it takes 60 seconds then you are doing 60 mph. the indicated speed tend to be a bit optimistic but the odometer tends to be dead on with factory wheels. My GPS tends to agree with your Scanguage for indicated speed. Speedometer is off by about 3 mph at 65 indicated.
 

Waterfrontray

Well-known member
Joined
Jan 14, 2008
Location
Tampa
TDI
2001 A4 Jetta
I go by a digital speed board every morning and it reads 45MPH when my Speedo says 48 - 50MPH. No GPS on the car. GPSs are for boats....:) Stock wheels and tires...
 

Shawnz

Veteran Member
Joined
Apr 14, 2008
Location
Peoria, AZ (Phoenix)
TDI
'02 Jetta GLS TDI, ex-O1M
Mine is the same way for the speedo. My Scanguage is my speedo now.

After 2-3 fill ups and assuming your driving doesn't change I think you'll find it to be eerily accurate. Mine is dead on in the city and will read slightly low if I take a road trip.
 

NarfBLAST

Top Post Dawg
Joined
Mar 3, 2002
Location
Waterdown, Ontario, Canada
TDI
2001 Golf 5MT
Speedo (instuement cluster) always shows faster than actual speed on VWs. Engine Control Unit (which Scangauge communicates with) shows a closer to actual speed. The odometer on the cluster shows closer to actual speed also (that is that it does not match the speedo). GPS may be different from the first three. You ground speed may be different depending on tire choice/wear/inflation.

By default the Scangauge displays the ECU speed but you can set the scangauge to match the speedo or a GPS unit whatever is your preference.

My VW Golf speedo was 6% faster than the ECU speed... most say this is normal. The ECU was 3% off I think... then I got bigger tires so my scanguage is set to plus 12% to match GPS.

Our Mazda5 speedo matches the ECU perfectly but have not checked against GPS yet.
 
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Sip'n Diesel

Veteran Newbie
Joined
Apr 13, 2008
Location
San Joaquin Valley, I have VCDS (KII-USB)
TDI
2003 ALH: 254,000 miles
Neous - on your next top off (you do vent all the way to the brim, right?) you will be entering a "consumption correction percentage" or somesuch, along with the price per gallon you paid. this is where the calibration (for MPG) can get too sensitive, or not sensitive enough. I'll assume you are familiar with how it works, it's pretty self-explanitory

now, here's my tip on adjusting that percentage: if your SGII "thinks" you used 9.50 gallons (for example) but you actually top off with 10.0 gallons (measured by the pump) then don't tell SGII you pumped 10.0. instead tell it 9.60, 9.70, 9.80, or 9.90 and after several tanks it should be getting closer and closer to being accurate

for awhile I would tell it exactly what I was doing, but it seemed that it would over-correct even though it had the "real" numbers. for example: if it thought I used 9.50 gallons and I actually topped off with 10.0 then I would tell it I pumped 10.0. logical, right? you would think this is more accurate, but in my experience it is not. I've gotten more accurate results by "lying" the the SGII than being "honest" with it. over time the results are more and more consistent, usually accurate to within one-tenth of a gallon +/-

on 2 occasions the SGII has accurately hit the number to the one-hundrendth of a gallon. for example: SGII thought I used 9.28 gallons and I actually pumped 9.280:cool:

I use a "speed correction factor" (or whatever they call it) of 3 IIRC. either 2 or 3 seem to be accurate to within 0.5% on the MKIV VWs

due to the speedo correction, the distances traveled won't match perfectly. for example: on a 700 mile tank (dash tripodometer) my SGII will think I traveled 695 miles +/-

IMHO it's not really a huge problem since @ 50 MPG, 5 miles is a discrepancy of "only" 0.10 gallons. also, I occasionally treat a tank with ~5.5 oz of PowerService which (I think) is a good amount to blend for 17 gallons. so, they kinda cancel each other out on tank averages:)

have you tried tweaking with any of the X-gauges yet? so far I've only added an X-gauge for the "current trip average MPG" and horsepower
 

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
I thought I was dead on after two fillups of 8.9 gallons at which I set my SG. The third fillup was .3G off, which I thought was close enough until I went and inflated a low front tire. That threw off the SG vs actual pump usage, so now instead of going back to default and reentering all the tank info, I will adjust on a tank by tank basis. I also recently set my sg speedo % at 4. That too has an impact on mpg accuracy.
 

Neous

Veteran Member
Joined
Jan 17, 2007
Location
Woodstock, CT
TDI
2009 Audi Q7
This is going to take a while to calibrate,
I messed up after my 2nd fill up so I'm back to square 1.
 

jettawreck

Top Post Dawg
Joined
Aug 2, 2004
Location
Northern Minnesota-55744
TDI
2001 Jetta and 2003 Jetta
Sip'n Diesel said:
Neous - on your next top off (you do vent all the way to the brim, right?) you will be entering a "consumption correction percentage" or somesuch, along with the price per gallon you paid. this is where the calibration (for MPG) can get too sensitive, or not sensitive enough. I'll assume you are familiar with how it works, it's pretty self-explanitory

now, here's my tip on adjusting that percentage: if your SGII "thinks" you used 9.50 gallons (for example) but you actually top off with 10.0 gallons (measured by the pump) then don't tell SGII you pumped 10.0. instead tell it 9.60, 9.70, 9.80, or 9.90 and after several tanks it should be getting closer and closer to being accurate

for awhile I would tell it exactly what I was doing, but it seemed that it would over-correct even though it had the "real" numbers. for example: if it thought I used 9.50 gallons and I actually topped off with 10.0 then I would tell it I pumped 10.0. logical, right? you would think this is more accurate, but in my experience it is not. I've gotten more accurate results by "lying" the the SGII than being "honest" with it. over time the results are more and more consistent, usually accurate to within one-tenth of a gallon +/-

on 2 occasions the SGII has accurately hit the number to the one-hundrendth of a gallon. for example: SGII thought I used 9.28 gallons and I actually pumped 9.280:cool:

I use a "speed correction factor" (or whatever they call it) of 3 IIRC. either 2 or 3 seem to be accurate to within 0.5% on the MKIV VWs

due to the speedo correction, the distances traveled won't match perfectly. for example: on a 700 mile tank (dash tripodometer) my SGII will think I traveled 695 miles +/-

IMHO it's not really a huge problem since @ 50 MPG, 5 miles is a discrepancy of "only" 0.10 gallons. also, I occasionally treat a tank with ~5.5 oz of PowerService which (I think) is a good amount to blend for 17 gallons. so, they kinda cancel each other out on tank averages:)

have you tried tweaking with any of the X-gauges yet? so far I've only added an X-gauge for the "current trip average MPG" and horsepower
Sip'n,
Agree 100% w/above info...except what about the part of "entering in the price per gallon paid". How/where in SGII do you do that? I've happily had mine for a year or more and never done that, but then I haven't gotten into xgauge features if it's in there. So much to learn...
 

mackconsult

Veteran Member
Joined
Mar 12, 2009
Location
Vancouver, WA, USA
TDI
95 TDI Passat Wagon
Waterfrontray said:
I go by a digital speed board every morning and it reads 45MPH when my Speedo says 48 - 50MPH. No GPS on the car. GPSs are for boats....:) Stock wheels and tires...
GPS is for what every you want. I use my hand held unit on sailboat deliveries and racing, my avon for fishing and other stuff, on my XR600R, in my automobiles, and as a hand held unit when hiking.
 

NarfBLAST

Top Post Dawg
Joined
Mar 3, 2002
Location
Waterdown, Ontario, Canada
TDI
2001 Golf 5MT
jettawreck said:
Sip'n,
Agree 100% w/above info...except what about the part of "entering in the price per gallon paid". How/where in SGII do you do that? I've happily had mine for a year or more and never done that, but then I haven't gotten into xgauge features if it's in there. So much to learn...
Maybe you have the older firmware version (lower than v3.15) that doee not have price of fuel nor xGauge features... may need to ship it in to Linear Logic to get the upgrade. Click menu, more, more, more until you get to "version".
 
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