Scanguage Miscalibrated? - Fuel Economy, Hypermiling, EcoModding News and Forum

stryker16 · 10-13-2008, 12:00 AM

Hey guys,

I just adjusted my Scangauge for the tires that I have on my truck. Before I was getting readings of around 16mpg in the city and 20+ on the highway. It was 19 for the tank. So, when I refilled the other day I also put that it was 2.7L and followed the manual for how to calculate how much is in the tank.

My tires now are 31.8" diameter and the stock ones are 28" ( I got this info from the web by typing in what tire size they were) So I did the calculation and got that I should adjust the speed setting by 12%, so I did. Now I am getting a reading of 26.5MPG mostly highway. I expect this to come down when I start driving around the city more as I usually do, but I wasn't expecting such a change (around 5 mpg gain at least). Did I mess something up??

Daox · 10-13-2008, 11:46 AM

If you changed the size of your engine you'll definitly have recalibrate the scangauge.

taco · 10-13-2008, 01:01 PM

so your came stock with the 225/75 r15? 28.3 inch tire that is what mine had.
and u have a 31 .8 so more a less a 265/75 r16?

yeah it is 12% but get a gps or another car and have it do 60 and u follow and adjust gps works the best.

i went from 225/75 r 15 to a 30x 9.5 r15 which is 5.xx% but on my calubration i have a 2 in speed.

stryker16 · 10-14-2008, 01:20 AM

Quote:

Originally Posted by Daox

If you changed the size of your engine you'll definitly have recalibrate the scangauge.

What? I just changed the default 3.0L on the Scanguage to 2.7L which is what my engine size is. I didn't change me engine.

Quote:

so your came stock with the 225/75 r15? 28.3 inch tire that is what mine had.
and u have a 31 .8 so more a less a 265/75 r16?

yeah it is 12% but get a gps or another car and have it do 60 and u follow and adjust gps works the best.

i went from 225/75 r 15 to a 30x 9.5 r15 which is 5.xx% but on my calubration i have a 2 in speed.

Yep. The side of my truck's door says stock tires are P225/75R15. New tires are BFGoodrich LT 265/75R16 which I found out were 31.8" This calculated to a 12% increase. I would love to use the GPS option but I can't afford one and don't know anyone with one. Maybe I'll try following a car at 60MPH though. Can you explain your reason for using 2 instead of 5% ?? Thanks

Daox · 10-14-2008, 08:05 AM

Yes, that is what I meant. If you change the size of your engine in the scangauge, you're going to need to recalibrate it.

stryker16 · 10-17-2008, 01:32 PM

oh you mean fuel calibration?? yeh i just did that it was around 12% also.

trikkonceptz · 10-17-2008, 04:00 PM

I understand that the scangauge can be calibrated, but since it is plugged into your OBT port, has your ecu been recalibrated also? or does it still think you are running your factory setup?

Are you guys sure that just adjusting the SG settings is enough?

stryker16 · 10-19-2008, 08:26 PM

Quote:

Originally Posted by trikkonceptz

I understand that the scangauge can be calibrated, but since it is plugged into your OBT port, has your ecu been recalibrated also? or does it still think you are running your factory setup?

Are you guys sure that just adjusting the SG settings is enough?

The scangauge doesn't change ECU settings. There are no codes on my ECU and it has always run factory settings. The MPG is down to about 20 in the city so I think it is working fine now.

brucepick · 10-20-2008, 08:01 PM

My understanding is - - -

You input the basic info into the ScanGauge and let it run. It will tell you what it thinks your mpg is for a tank.

Then you calculate your ACTUAL mpg from tank fillup quantities and actual miles driven. Here's where your tire size will make a difference, you have to know how many actual miles regardless of changes to tire size or rear end ratios etc. Doesn't matter how you find the actual distance but I think most of the time getting it from the odometer plus calcs on tire size and any rear end ratio changes is best/easiest. Unless you have a GPS.

Then compare actual mpg to what the ScanGauge says for that same tank/fillup and you can get a correction factor. One that will add or subtract some percent to/from the Scangauge result to make it match your real world result. You enter the correction into the ScanGauge and after that it's pretty accurate.

If you want to do engine-off coasting, tell the S-gauge your car is a hybrid. That allows it to continue measuring distance when engine is not running, as long as the key is in the "On" position (usually would make the battery and oil idiot lights light up).