Worse Fuel Mileage

[dford]

We put a power puck on a friend of mines 05 1 ton Dually. The computer says that he is getting 19 or 20. When he puts a pen to it...its getting about 13. Before we put this chip on the truck it would get 15 stock... Whats going on here... We have seen good mileage from a 2006 Megacab?

[johan]

Is it possible the guy is floggin the throttle a little more with the puck on there maybe. A lot of people do not realize they do with the added power as it is addictive but we have not had any negative reports on mpg with the pucks.