Loss of Gas mileage

[WileE7]

Recently i put 4.56 gears in my bronco i was averaging 11 mpg after i changed them I haven't drove it for about 3 weeks and now i get 8-10 mpg i fixed the cracked line on my vapor canister i can't think of anything else that would affect my gas mileage any ideas?

 

[Seabronc]

Did you do anything to recalibrate your speedometer? Also, that will increase your engine RPM in order to go the same speed you normally cruise at, ergo lower mileage. ex. if you had 3.08, then your engine had to turn 3.08 times in third gear for each revolution of the wheels, 4.56 means your engine has to turn 4.56 times in 3rd gear to turn the tires one revolution. If you have OD then that helps some but still requires higher RPMs to sustain a given speed.

Good luck,

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