2007 Durango w/MDS @ 68k miles. Gas mileage has gone down in wifes Durango over past couple months 12-14mpg. Got around to driving it the other day and in order to get the torque converter to lock up at highway speed, you pretty much have to lift your foot completely off the gas to get it to lock and then your good for a while. It is not MDS locking and unlocking, i know it does that; it is not initially locking up. Warranty is expired and dealership wont suggest anything with out a full diagnostic analysis. I remember having to ease off the gas to get it to lockup sometimes after we bought it 2 yrs ago, but now you pretty much have to almost start to slow down for it to lock. Any suggestions?

 

The torque converter should lock up when you maintain a speed, it doesn't matter 3rd,4th or 5th gears. You can ask a tech to go on a road test, just to verify lock up.

 

The converter does lock up when you take your foot off the gas pedal almost all the way to the point of deceleration. If you keep it steady w/o lifting off the gas, it will not lock up and the rpm's will not drop; even on completely flat road. Dealership will not even let me talk to a technician without paying a diagnostic fee because i am out of warranty. I normally do all of my own maintenance anyway, but i am clueless when it comes to transmission work.