20cherokee00

hey everybody im new here and this is my first post. so here's my problem.. i have a 2000 xj 4.0 with 89,000 miles on it. on my last quarter-tank i only traveled 32 miles which is about 6.5 mpg. i know when i bought my xj last year that it was gonna get horrible gas mileage and i've been pretty content with the 10-12 mpg i've been getting, but why this sudden drop off of 40-50%? i ran out of ideas so i hope you guys can help me. i changed the plugs 2,000 miles ago and i just got a new air filter. i run valvoline high mileage 5w30 syn blend. i hope im missing something so i can fix it asap. thanks everyone


nik

kilbrethj

what did you put in for plugs? you shouldn't be getting that bad. I was getting 14mpg then changed cat and o2 sensor and my milage has gone up 1mpg with every fill up so far. up to 16.5mpg. i doubt your cat or o2 sensor is bad... alignement helps to... stock tires? how are you checking your mpg's?

20cherokee00

i cant remember exactly..either champions or autolites but im pretty sure they were champions. im just doing the mpg's in my head. 20 gallon tank = 5 gallons per quarter tank. 32 miles traveled divided by 5 = 6.4mpg

joshpallotta

i dont think you have a 20 gallon tank. i think its a 17. that can mess up your calculations

20cherokee00

its definately 20 gallons- i just google'd it to reassure myself.

projectmayhem

have u checked ur float

20cherokee00

huh?

EvilBlackXJ

Going by the gauge to figure mileage will not be accurate. Most gauges I've seen go down slowly at first and faster the lower you get in the tank. You need to fill back up, see exactly how much gas you put in and divide the mileage by that. Even then, going by that little usage will not give you an exact mpg. Was that all highway, or all stop and start driving?

20cherokee00

mostly stop and go, and i'll take your advice. thanks