same as no ac condenser ect..

 

There must be something wrong with my truck. 2003 3.9 4x4 Dakaota automatic. I get 15-16 on the highway with cruise. Shold I have it scanned? What about a larger throttle body?? More air??

 

change ur o2s latley?

 

With the SCT tuner showing up on the market to reflash Chrysler OBD-II PCM computers,
someone could experiment with setting highway cruise
to a higher air to fuel ratio than 14.7 to get a fuel economy gain

Two things need to be found out:
...how high an a/f can the various Dodge v8s and v6s ignition systems go to before miss-fires become a problem
...hwo much fuel economy gain is at each a/f like 16, 17, 18

most of the engineering tables on aircraft engines show about 7% better at a/f of 17
but the ignition system needs to be strong to keep firing that lean

 

Wouldn't a bad o2 sensor show up on the dash as check engine? Also it just went through emissions and passed well. As for the thermostat being changed to 180dg, I thought the hotter an engine ran, the better it runs mileage wise.

 

no

 

Does it really make that big of a difference (the tstat that is)?? I mean i cant imagine that 15deg would make a world of diff.

 

it does...

my wifes 2002 3.9 cc got 16's on the hiway... once in a blue moon she'd get 17.

 

as said, keep yer foot out of. I bought an Extang bed cover and mileage went up about 2-3 MPG.. it paid for itself on the move from Florida to Utah. also keep your oil maintainance up. and check tire pressure regularly.

 

I used to get 20-21mpg but now its around 17-18mpg. I think my tires and lift have more to do with. but I'm still happy.


when myO2's went, I was down to like 12mpg and they didnt throw a code at all.


if I could baby it for 1 tank, I bet I could get back into the 20's again. but Idont see that happining.