I've run three tanks of gas through my new (to me) 2006 SS/SC with GMPP Stage 2 installed. My DIC tells me I'm getting 26-27MPG, but the old school slide rule method comes up about 4MPG less, around 22-23MPG. I reset the DIC with each fillup. Does the stage 2 reflash not take into account the higher flow injectors? Or is there something wrong with my 'Balt? Anyone else see this sort of thing? Or is this my DIC's revenge for all the beatings it took as a teen?

 

its all a guestiment, no matter what it will be wrong

 

Weak dude. I was all excited because I was only getting 24MPG in my VR6 Jetta and thought I was now getting 27MPG.
I guess that means YOU GOTTA PAY TO PLAY

 

its no guess. The DIC measures the pulse width of the injectors and plots that against mileage covered through the vss.. Try calculating fuel mileage with your slide rule calculations on the price of the gas consumed, against its cost per gallon and redo your math with more accurate volume calculations. my guess is the dic is right...the gallons pumped permits error, the price per gallon gives you a few more decimal points to work with....

 

Mine is usually about a gallon per mile more optimistic than my calculations