No luck!
refueled today and mileage was in same range as before. guess when i disconnected battery it somehow reset the scanguage adjustment and now that i refueled it's all messed up. i set for what i pumped and reading was way outa whack. checked the adjustment when i got home and it was showing -56%!! wtf?? i'm almost ready to get rid of the thing.

Mike, are you ever going to stop adjusting your SG?? I will try to help again.

Clear your settings by (use default settings). Set your tank size to 12 gallons. Set your fuel type to (hybrid). Engine size to 2.0. Use the 1 extra click method to fill, and please use 1 extra click method for every fill thereafter. Changing your fillup method constantly confuses everything. Then go to fillup (push done) do not ever change settings, just push done. Make sure you have 0% adjustment. Do this for a couple tanks and you will have your SG stabilized.

When you make the adjustments you have been making, you are essentially telling your SG it is wrong and your filling methods and pump inconsistencies, tilt, and temps are always right. What would you expect it to do? You are telling it what to do and when it does that, you don't like that.

I know in my own experience SG has been very accurate in recording the amount of gas used. I believe the vast majority of lack of agreement between SG and gallons pumped is filling methods.

I use gallons pumped to keep records and I do not adjust SG at all, over a
period of time SG gallons used will become very close to actual.

Hope this helps. Again. CO ZX2

it got messed up when i put in new battery. i just changed all to original setting. 2.0 engine, 12 gal tank, 0 fuel ajustment and hybrid mode. i had it pretty close before the battery died on me.

Whoa.... I thought the only feedback the SG got was when the user completed the loop and physically entered how many gallons were actually used. Is there another feedback loop the SG uses automatically?

I'm going to do a reset and try the method you just outlined. I've been consistent with my fuel ups as the adjustment is typically no more than .2 gallons either way. I also round up to keep the SG on the conservative side of error :p

hmm i have the same engien and prolly the same PCM in my truck. i just replaced my o2 sensor maybe 3 months ago but never disconnected the battery. i also yanked the egr valve off and nevr disconnected the battery.
maybe i will try that later today...see what happens. i dont have a very good baseline mpg tho usually around 22-25 but since i yanked the egr off its been high 27's 28's.

One of the issues with my Civic was the ECU. I had it replaced once. But the car would get into a ,,, Im not going to do good mpg for you mode. I would reset the ECU and it would come right back up for a month or so.

Very strange. One of the many reasons it had to go.

A peek inside my ecu shows a few things that might help FE when it's reset. Or it might not. As usual, other cars may respond differently depending on their strategy.

Here's a list of the things that are remembered by the ecu and adjusted to account for different driving conditions
Octane. My car has a variable that is subtracted from the calculated ignition timing to make up for frequent or large ammounts of engine knock, i.e. bad gas. When knock is heard the octane value is slowly lowered from 100%. Naturally the ignition timing is pulled immediately, too. When the octane value is less than 100% it pulls timing all the time to prevent knock. If you're not getting knock, then resetting the ecu will bring the octane value back to 100%. If you are getting knock, resetting the ecu will give you more knock until the ecu can readjust. If the motor is old and knocks from loose parts, the ecu might read this noise as real knock and pull timing+octane. In this case resetting the ecu will help briefly.

Fuel trims. Personally I prefer that these don't get reset since they help the ecu add the right ammount of fuel instead of guessing wildly. IIRC all OBD I and II cars have fuel trims.

Idle speed control motor position.
And of course all the error codes will go away until next time.
OBD II will initialize it's smog test readiness cycle again.

Once you get it stable again, when you fillup after running a full tank thru it, note the % of fuel adjustment. You will need to reset that or consumption and mpg numbers will be way off. Mine is at over %12 on the saturn.

Also, you need to reset your mileage adjustment, so make sure to write it down. This adjusts for the difference between how far the car thinks it went vs real distance checked via GPS or mile markers. Most cars are off by at least 1/2% from the factory.

I hit these same problems each time I move the scangage from one car to another. Writing down the settings and putting them back in the same is the solution.