I'm new to the Dodge scene, so i would appreciate any suggestions for my problem: my little 3.9 4X4 averaged 17-18 miles per gallon when I first bought it (fall 2005). In the last month I have seen it fall to 16, to 15, and now down to 14 MPG. The only recent change I have made was cutting off the poor sounding duals and glasspack that were on it and returning a more stock muffler (no check engine light following change). The truck has an AIRAID cold air intake, and because I drive on gravel fairly frequently I have pulled the filter and cleaned it...it was pretty nasty, but I can't imagine a 3 MPG change due to that alone. Please give me some suggestions...fuel filter, injectors...any educated guesses will b appreciated.

 

Wheel alignment?
Low tire pressure?

Only educated guesses I have.

 

checked all the tires a couple weeks ago and evened them up, although they weren't off by more than a couple lbs. As far as alignment, seems to go down the road straight as an arrow

 

Fuel injectors could be cleaned, possibly 3 step system. Transmission fluid could affect it. Try disconnecting your battery for 5 minutes try starting it and it'll reset the computer.

 

Had tranny fluid changed in about Dec. Should be fine I guess. Explain what u mean by three step system please. And to reset the computer, I should try starting the truck while the battery is still diconnected, or do u mean to disconnect for five min and then hook it back up and fire it up? Thanks for the input

 

Change the oil? Is there synthetic oil in it now?

 

Oil and filter changed religiously every 3000. Not running synthetic ...always use Q...doesn't use any oil.

 

Check out:

https://dodgeforum.com/m_387238/tm.htm

?

That might help?

 

Cleaned my air filter, but that only got me to about 14.5 MPG. Any other suggestions? Thanks for the input thus far

 

OK, I went through a diagnostic book and the causes listed for loss of MPG are as follows. Keep in mind these are all generic causes in order to be able to diagnose more vehicles, and therefore are not limited to this make or model in any way.

Air Filter
Heat control valve stuck open or closed
PCV Valve stuck open or closed or dirty PCV Valve
O2 Sensor defective
Incorrect ignition timing
Incorrect idle speed
Fuel leak
Fuel injection internal parts worn or damaged
Cold start injector, if equipped.
Parking brake stuck
Defective carburetor

Hope this helps a bit.