poor gas mileage - ideas?

[Radley]

so.. this summer mostly highway was getting 18mpg.

2 fill ups ago, checked, was down to 15 mpg... ok... it has been cold..

ohyeah 2000 t4r sr5 3.4 4wd.

last fill up and mileage calculation... 11.2 mpg !! wtf?

checked online, possible vacuum leak... how do I check that, anyone deal with this before or is there somptin on these models that typically faults, other than lbj and trans cooler, lol.. ?

any other ideas? ran some injector cleaner thru few fillups ago.. CEL is NOT on.... saw a Utube vid with no CEL and had poor mileage...guy hooked it up to some computer and checked banks 1, 2 or somptin.. and was able to test with a SMOKE vacuum leak check unit thing... yeah that's 500 bucks, lol.

so.... what do you experts think about this one?

oh yeah. i know running in 4wd has been minimal, but regardless. 11.2? ok what ya'll think?

thanks!

 

[nissanh]

Sorry not much help here. I am looking pretty similar numbers in the city. My 100 series LandCruiser AWD V8 is also doing 11 MPG in the city! Probably 5VZFE is bit too hungry.

 

[wemslie97]

How are the plugs, wires, MAF, Etc...usual tune up stuff?
Also could be 02 sensors, clogged cat., pcv, or Like you say, a vacuum leak. Cold weather is ***** on vehicles and mpg's.
Hope this helps.