Possible problem with MPGuino mileage readings.
 

My MPGuino has only been installed on my civic VX for a couple of fill ups now but it's been slightly off in both directions. First it read too low and I calibrated it up, then it read too high and I calibrated it back down... I know it's common to have to calibrate the MPGuino over a few tanks, but I noticed something today that might be throwing off the calculations.

When I'm stopped at idle the instant mpg gauge switches to gallons per hour. When the engine is cold and idling higher/using more fuel, the gauge stays in gal/hour (about .25-.35 on a cold engine). But once the engine is at operating temps and I come to a stop, some times it keeps switching back and forth between gal/hour (usually reading .10-.12) and instant mpg (which always reads 0.00 because I'm stopped). I notice the current/trip mpg won't decrease unless the gauge is reading in gal/hour. When it reads instant mpg is 0.00 my current mpg's stay the same and do not decrease.

I feel like I'm rambling, but I guess my question is if this is a problem with my specific MPGuino or is it normal? And is it affecting my current/trip mpg readings, therefore not allowing me to accurately calibrate the MPGuino?

Any help is appreciated, thank you.

Mine doesn't switch readings while stationary. You could try uploading a different version of the software without this feature/bug if you're sure it's causing your issues.