and the results are in!
230miles on 5.72 gal = 40.2mpg
198miles on 4.80 gal= 41.2mpg
207miles on 4.85 gal= 42.6mpg

and just for your info miles on trip were rounded DOWN (ie 207.5 was rounded to 207)
gallons of gas were rounded UP (ie 4.846 was rounded to 4.85)
This is how i went about doing this... on the FIRST tank i got gas, let ecu reset (switch off overnight) turned the switch back on and drove the 230 miles (the needle was still above half tank) the SECOND tank i reset the ecu right after i got the fuel AND when the trip had 100miles on it.... the THIRD tank i reset every night... i dont think this is something i would do all the time especially with gas back down to $3.13 but it was interesting to find this out

 

Nicely done. I assume the first set of mpg values was obtained without the ECU reset procedure and the second set was obtained with the ECU reset procedure. If so, your data suggest that resetting the ECU gives you an approximately 10% increase in gas mileage.

I'd sure like someone to explain this interesting observation. Does your state have annual inspections that require emissions tests? If so, post the data. All I can come up with is that the reset procedure temporarily causes your engine to run slightly lean while the ECU relearns the normal drive cycles. This would predict that your NOx emission levels may be high during the relearning process. Anyone else?

 

yeah... the first 3 tanks were without the ecu being reset the last three were with the ecu reset. my state does have emissions BUT my county doesnt have emissions :P. i agree with the idea of the engine running lean and i also notice smoother shifts... (auto trans) but i dont think i'll keep on doing this cause im sick of reseting my clock and stereo every time i turn off the ecu... plus i saw gas for $2.98.