I recently traded in my 2005 durango for a 2007 durango, both were hemi 5.7l with the 2007 having the MDS motor. I noticed immediately that the 2007 idled higher at start up before eventually settling down. My city MPG dropped on my 2007 to 11MPG from 13 mpg for my 2005. any ideas out there on why the MPG drop for the newer durango? I was wondering if maybe the previous owner installed a performance chip.

 

How many miles on the 2007? Could be a sensor thats not working properly.

 

A clogged fuel filter could cause the engine to surge at idle, but it would do it after start-up too. There are chips which are useless and then there are programmers that will install a program in place of the factory one. I have a stage II Jet Performance chip that I never opened and they plug into the ECM if I remember correctly,
FF

 

If there is a chip, it is indeed plugged into the PCM. Additionally, it is junk and unless recently installed, the PCM has already calibrated around it making it useless.

More than likely just differences in the tune via plugs, sensors, etc.

IndyDurango

 

Just drove 300 miles on the highway and averaged 16 MPG. Terrible. This durango also has the MDS system which I thought was supposed to improve highway mileage? I will look into a tune up, but dealor told me they did it before I bought it. Thanks for the help.

 

16MPG is about right for that big brick with the HEMI. Gas mileage friendly these are not nor were ever reported to be.

 

But my 2005 Durango with the Hemi got about 18/19 on those long trips. The purpose of the MDS system (I thought) was to improve highway gas milage, not reduce it.

 

Different aero, diff tires, diff gas, diff motor, diff history, diff oil, diff miles, diff upkeep, diff plugs, diff filters, diff everything. Can't really relate the two and it ALL matters.

MDS is a system to save fuel yes... under certain situations... like government testing labs for CAFE and mileage standards.

Again, 16-18 is fine/normal for pushing that huge *** brick through the air powered by the HEMI.

 

I average 14 MPG that has the MDS system,
FF

 

Drive it like your Demon FF.

14 hell... Let's go for 12! You'll match mine then!! LOL

IndyD