Engine/Transmission (1998.5 - 2002) Lost my fuel mileage!!!!

[curatchko]

I was getting almost 21 miles per gallon on the e-way about 2 months ago. Only change I've made since is these tires and now I'm getting 16 on the highway... .



Almost 5 mpg??? Truck runs great... . but my mileage took a poop.



could it be the fuel filter? I haven't changed it for about 16000 miles...



I have good fuel pressure. 13. 5 at idle, and about 10. 5 cruising down the freeway... this is post-filter. Drops to 8 at WOT. :{

 

[Riflesmith]

Your odometer should be off by around 8% following a switch from 245's to 285's. Add 8% to your miles at fill-up and your mileage calculation will be more accurate. Forgive me if you are already aware of this.

 

[curatchko]

Thanks for the tip...



But that still only puts me around 18 mpg. Still around 2 mpg down.

 

[Got Smoke?]

Originally posted by curatchko

Thanks for the tip...



But that still only puts me around 18 mpg. Still around 2 mpg down.

Your always gonna lose some mileage when going to bigger tires.

If you went from 245's to 285's then yeah that sounds about right "2mpg". The fact that you have an auto makes it a little harder on the mileage with the edition of bigger tires.



I had a Toyota 4cyl auto truck before I got my CTD, went from 30x9. 50xR15's to 33x12. 50xR15's boy was I :{ :{ :{ at the pump. But I was off road! :-laf

 

[curatchko]

Well then it's time for them 4. 10 gears... . no more messin around!!!!!

 

[Adam]

Winter time?

You don't list where you're located, but is it possible the fuel stations have started to run a winter blend? I usually lose 2-3mpg when the winter stuff hits the tank.

-Adam

 

[curatchko]

I'm in Michigan... . that might be the case.



Thanks