ScanGauge tuning

[vectorg]

I have learned from using my ScanGauge for several months that it registers my trip-mileage at between 25% and 33% low.

What is the menu or key-sequence for me to make this calibration to my ScanGauge? I read the manual about a method to calibrate when doing fill-ups, but didn't see a general adjustment like I need.

Is there a way to make a general calibration like this?

Thanks.

[Rick Rae]

Odd that it's that far off.

Is the speed reading off proportionately? If so, there's a speed adjustment factor that would likely correct the distance thing too.

If mileage is off but speed is correct we're back to "odd."

Rick

[Jay2TheRescue]

Mine was off till I got my speed reading calibrated as well. The best way to do it is this:

Change your GPS and scangauge to readings of kilometers (Kilometers are smaller than miles, so you'll be able to more accurately dial it in.) Get on an empty stretch of highway with the GPS and a competent passenger. Accelerate until the GPS reads you are traveling @ 100 KPH and set the cruise. Verify that once set the vehicle maintains 100 KPH. The passenger should be able to change the % variance in the speed settings until both the SG and the GPS read 100 KPH. Change the vehicle speed and verify that the readings are still accurate as compared to the GPS. If so, save the setting on the SG, and exit.

Then just switch the SG and GPS back to MPH. The whole process is outlined in the latest version of the SG manual. If you don't have the latest version you can download it from www.scangauge.com.

-Jay

[Rick Rae]

Great details, Jay; thanks!

Just a suggestion, vectorg: Once you have all your calibrations (speed, fill-up, tank size, etc.) worked out, jot them down -- a small sticker on the back of the Scangauge would be good.

Twice I've had service-related disturbances that reset my Scangauge to factory defaults. If that happens to you and you've recorded the numbers, you can just punch them right back in. Otherwise you'll have to go through another tank of gas and make a calibration run to get things right again.

Unless you have a much better memory than I do.

Rick

[vectorg]

Originally Posted by Rick Rae

...you'll have to go through another tank of gas and make a calibration run to get things right again.
Rick

Thanks Rick. I'm wondering how to make this calibration on-the-spot using the info I have now, without going through more tanks of gas.


I've driven past some radar-speed-detector things recently, and my speedometer seems to be accurate. The SG is also very close to my speedometer.

Last week I drove from SoCal to San Francisco and my SG showed 24.7 mpg, yet my fillup calculated to 33 mpg. Then, on the way home, I used P&G with drafting of large trucks. My GS showed around 32 mpg, and my fillup revealed over 48 mpg.

These numbers follow the pattern that I've seen since I got my SG.

[Rick Rae]

Originally Posted by vectorg

Thanks Rick. I'm wondering how to make this calibration on-the-spot using the info I have now, without going through more tanks of gas.

My suggestion was to help you avoid calibrating again. No connection to what you're doing right now.

The SG is... very close to my speedometer.

You originally posted that your trip mileage was off, which is what prompted replies about your speed calibration. If your speed is reading correctly, then the Scanguage knows how far you're traveling per unit time as well.

Last week I drove from SoCal to San Francisco and my SG showed 24.7 mpg, yet my fillup calculated to 33 mpg. Then, on the way home, I used P&G with drafting of large trucks. My GS showed around 32 mpg, and my fillup revealed over 48 mpg.

It sounds to me like your fuel usage is what needs to be calibrated. Have you set the displacement of your engine? When you fill up, does the amount you put in the tank differ significantly from what the Scangauge is expecting? Are you making that adjustment when you fill up? Does the correction factor change from tank to tank?

The first couple of fills should have gotten you very close to perfection.

Rick

[Jay2TheRescue]

Good point. I had made the assumption that the engine size and such had already been set. Also be sure to enter the number of gallons purchased into the SG when you purchase fuel.

-Jay

[vectorg]

I've never made any adjustments or calibrations to my ScanGauge. I thought it was a plug-n-play type thing. Are you saying my car's computer doesn't even know the displacement of it's own engine?

When I say "trip" mileage, I just push the trip button when driving somewhere to see my average mpg as I go. Or, I push the "gauge" button to see the real-time mpg.

I'll go read the manual again.

[Jay2TheRescue]

Yes, the computer knows what size everything is, but the SG is trying to calculate fuel usage based on the live sensor data it reads. Knowing what size the engine is, how large the fuel tank is, and how many gallons are put in the tank at each fillup helps it calibrate.

-Jay

[vectorg]

Thanks, Jay. I just looked, and changed engine from 3.0 liters to its actual 2.2 liters. Should this adjustment cause me to see a difference in my trip and real-time mpg readings as I'm driving?

Other units looked okay for now.