Fuel Milage Loss

[bugg88]

I recently installed a Banks exhaust brake along with the monster exhaust system on my 2002 Duramax dualie. My fuel milage has fallen from a range of 10-11 mph to a range of 8.2-9.8 mph. I pull a 37' Cardinal 5th wheel.

I have contacted various tech reps at Banks and have had a range of responses. Several reps said no way this could cause milage loss. Another said he thought the monster exhaust could lower milage and that I should try replacing the pipe from the exhaust brake to the turbo exhaust pipe with stock.

I'm confused as it doesn't seem like this could help. Could the installation of either the exhaust or the monster exhaust cause a drop in milage?

I like the whole system real well and I would prefer not to it change but I don't like to lose milage. Any input will be appreciated.

[chuntag95]

bugg88,
How many tanks of data are you using? Did you change fuel suppliers? Could you be putting your foot in it more than before? Have you checked air and fuel filters? Sorry I only have questions and no answers, but I agree that you shouldn't be seeing this.
Chris

[britannic]

Is the exhaust brake working properly (not staying slightly closed)?

More back pressure would be one cause of higher fuel consumption.

Have you seen any differences in the boost and pyrometer gauge readings?

Does the brake integrate with the transmission and therefore your shift points are being affected?