Gas Mileage Questions

just wondering what could be wrong..im not doing anything different and havent even put my new tires on, but my gas mileage went from 20-21 mpg to now about 16-17. i do hear a clicking type noise every once in a while tho, could it be the cvs or that cat? not sure

i have billy 5100s set at .85 and everything really that i have read is saying that lift wouldnt necessarily cause a drop in mpg, that it is the size of the tire that would. i mean im expecting to be around 16-17 when i put my new tires on, im just wondering why my gas mileage has gone down with nothing being changed? anyone know what could be the issue?

thanks for any input

 

What motor? Auto or 6speed? Clicking could just be the notorious taco tick... need more specifics... tire size could definitely be a factor I get 16mpg and I drive like a grandma... plugs been changed? Air filter condition? Gas being used? ...

 

4.0 V6
Auto
doesnt sound like an engine click or anything..almost metal on metal, pretty sure its cvs tho
regular unleaded
air filter changed with oil change 500 miles ago

 

Ok good and good ... I use premium and notice a slight change... seafoam every month in your gas to clean out fuel system, when were the spark plugs changed last? ... metal on metal ... hmmm if it's the cvs, any vibes? Patterns with the noises?

 

just bought it in july..havent checked spark plugs..but i will now. and yea noise is with accelerating and turning while accelerating. i wouldnt necessarily say theres vibrations tho i guess there might be a little. either way would cvs even be a cause for gas mileage?

 

I'd check wheel bearings/hubs first... those are known for going bad... your mileage at 16/17 doesn't sound that bad to be honest ... how long have you owned the truck?

 

Just throwing this out there. Does your clicking stop when the brakes are applied? I just had a clicking that would increase with speed. For some reason my front passenger side caliper was holding too much pressure on the brake pads. They were dragging on the rotor and clicking when the rotor would make a full rotation. The sound would dissapear when brake pressure was applied. I pulled the assembly apart, pressed the caliper pistons back in and reinstalled everything. Clicking stopped and everything seems to be working fine again.

 

This could effect mpg's lol