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Hi all, this is my first post and I hope you can help me. Iv'e had my SGII for about a year now and I love it, but I have one minor problem. The fuel offset keeps changing and I'm wondering if anyone else has run into this or can explain why it happens. I track and record every tank, both actual and SG. For the first 2000mi. or so I was avg. 5-5.5% offset. Then it dropped off to 2-2.5% avg. fairly quickly and stayed there for about 4500mi. It's started climbing again over the last few tanks though. I'm up to 6% now and I think it will need to go higher. Other than a minor speed offset adjusment that has to be made for in town or on the highway, nothing else has been changed. Any suggestions?

That sounds like a summer / winter fuel blend change. Check the dates when the change happened.

It's possible, but the dates don't really seem to line up to me. I don't understand, though, how fuel quality would affect the Scangauge calibration. Could you please explain.

Shorter version: Sg expects same level of "efficiency" per gallon of fuel indefinitely. Winter blend and summer blend have a different "efficiency." From what I've read on here, the summer blend should be more efficient, however, I haven't been able to isolate that condition in my 14 months of logging my mileage.

My fuel offset changes by about 4% with E10 compared to straight gas. It's right on with real gas, and 4% optimistic with E10.

Ethanol fuel, or winter blend fuel, or both (even worse) has lower energy per gallon. The Scangauge estimates fuel used by measuring airflow, since that's all that's reported to the OBD plug. It only knows the airflow, and the ideal air-fuel ratio. If you change the fuel type (winter / E10 / whatever) or the ratio (lean-burn like the Insight or a diesel), it will be off and you'll have to adjust it.

It measures air flow only? Darn, I guess this thing isn't as smart as I thought it was going to be. How can it be accurate when my fuel injectors are shutting themselves off during deceleration?

It measures air flow only? Darn, I guess this thing isn't as smart as I thought it was going to be. How can it be accurate when my fuel injectors are shutting themselves off during deceleration?

It has a fuel cutoff parameter that recognizes DFCO as a combination of TPS and open-loop. MORE> SETUP>FUEL> CUTOFF> and set it to 1 or 2 above your idle TPS setting.

Unfortunately, it isn't in fuel cut the whole time my foot is off the throttle, and I barely need to touch the throttle to keep it going at around-town speeds. I haven't actually received it yet, so I'll just have to wait and see what the TPS readings are. I may be worrying over nothing.

This is an interesting discussion that has helped me with my own SG setup. I do need some more information, however, on setting the cutoff. My idle TPS is 0 or blank. So when I set the cutoff, I supposing the engine should be warmed up or aleast showing an open loop?

I go from 8% with winter gas to 2% with straight summer gas.

My now ancient SGI has no compensation for dfco or for FAS for that matter reading a constant 0.1 gph with the engine off.

Can I send this museum piece in for an upgrade?:eyebrow:

I think the settings for the HCHII were different, it acts really strange unless you match the cut-off to something it shows when in an auto stop, a very different number from idle or key off conditions.

I go from 8% with winter gas to 2% with straight summer gas.

My now ancient SGI has no compensation for dfco or for FAS for that matter reading a constant 0.1 gph with the engine off.

Can I send this museum piece in for an upgrade?:eyebrow:

I think you can get the upgrade for DFCO and FAS for $25. I haven't done it yet.

The 0.1 gph is a toyota thing. My sister's camry does the same.

^

Guess I should e-mail and see what they can do for me.

If and increase or decrease of 2-6% is normal what would 19% be??

The last time I filled up the change was from 16% up to 20.1% in the first week in May. I just fillied up on Friday and it just from 20.1% to 39.4% what gives? Should I have kept it at 20% or decrease it to 16% as this mornings drive the MPG's I could barly get to to 2-4 MPG of what I have been getting under similar conditions. The 20% change was way OVER estimating what fuel (was still saying I had 6 gals left when I filled up with about 3 left) I had left and was way UNDER reading the milage (about 50 miles low) traveled.

Do you think I should just fill it up again and put it back to 0 and go from there or average all the changes since I stated using the SG and go with that number?

Thinking back without looking at the number right now (don't have them here at work) I am thinking that when it was at 16% it was reading very close to what was going on.

Any advice or help would be great at this point, because I don't want to go though this tank seeing 19-20 MPG when it should be aroung 21-23 MPG's, although it would be a great suprise at fill up :D:Banane18:

I would note all the specific settings (other than the fuel one -- so cut-off, speed, engine displacement, tank size, and fuel type), then do a factory reset and put those settings back in.

Run a tank and see if that fixes it for you.

Just so we are all on the same page, what procedure are you using to adjust the fuel offset?

when I fill up I look at the gals pumped and increase or decrease the number on the SG to match (isn't that the manual says to do?). After looking at Andrews method of filling I think I will start using 1/2 the adjustment.

Is that the information you were looking for?

Yes -- that sounds correct.

I don't know why your offset would be increasing so drastically...

If I reset to factory defaults I will lose any Xgauges that I have added right?

here are the numbers from the fills
first fill after a few miles on the SG to get the calibration started - 16.6%
second fill - 7.1%
third fill - 3.8%
fourth fill - 16.8%
fifth fill - 16.8% (I don't think I changed it)
sixth fill - 20.1%
seventh fill (the latest) - 39.4%

I think that at 16.8 it was just a little off on the low side so I my put that number in when I recalabrate. I will need to note the changes on the record sheet I keep.

Maybe it is fliping out with the increse in FE :Banane18::rolleyes: