Turning off MDS

That's enough....

After reading this thread, I turned MDS off (using the paddle gear selectors) and just returned from a 355 mile round trip for the weekend. I was amazed to see that with MDS off I also experienced a ~ 2 mpg improvement. That's hand calculated. My driving was consistent to previous trips. On the trips with MDS normally engaged, the absolute best I ever saw was 20.2 mpg on one trip leg when I kept speeds to 65mph. Driving normally (for me) with speeds between 70 and 75 sometimes a bit over, and not babying the throttle when passing, I usually would see high 18's and low 19's in miles per gallon.
On the first leg (175 miles) I got 20.95 mpg which was hand calculated, and on the return leg I got 20.68 mpg, driving the same way.
I was very surprised but I'm not complaining.
Another thing I noticed was my transmission temperatures were 3 to 5 degrees cooler with MDS off during the hiway driving, something I clearly don't understand. With MDS on, my trans temps usually are in the 186 to 188 degree range just about all the time. With MDS off, those temps were in the 180 to 182 degree range. I hope this is just a fluke as I can't envision any connection.

tsielski said:

After reading this thread, I turned MDS off (using the paddle gear selectors) and just returned from a 355 mile round trip for the weekend. I was amazed to see that with MDS off I also experienced a ~ 2 mpg improvement. That's hand calculated. My driving was consistent to previous trips. On the trips with MDS normally engaged, the absolute best I ever saw was 20.2 mpg on one trip leg when I kept speeds to 65mph. Driving normally (for me) with speeds between 70 and 75 sometimes a bit over, and not babying the throttle when passing, I usually would see high 18's and low 19's in miles per gallon.
On the first leg (175 miles) I got 20.95 mpg which was hand calculated, and on the return leg I got 20.68 mpg, driving the same way.
I was very surprised but I'm not complaining.
Another thing I noticed was my transmission temperatures were 3 to 5 degrees cooler with MDS off during the hiway driving, something I clearly don't understand. With MDS on, my trans temps usually are in the 186 to 188 degree range just about all the time. With MDS off, those temps were in the 180 to 182 degree range. I hope this is just a fluke as I can't envision any connection.

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Awesome data thank you for posting! If you do another trip in the future with MDS disabled please post here again.

Just out of curiosity, what did the dash say the mpg was? My dash usually says it's getting less mpg than it is hand calculated with MDS disabled and more MPG that it is hand calculated with MDS on...

swanny297 said:

Is it better to use tow/haul or run through the gears on the column?

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According to Ram engineers Tow/Haul mode will not turn off MDS, the only way to deactivate it is through the ERS range selector.

Also I will note I do get better mileage with MDS than non MDS. This was averaged through several thousand miles and not just one tank and averaged about 2.5 better mpg.

The EVIC mpg readout for the trip was showing 19.7 mpg with the MDS off, and as I posted, the hand calculated mpg was higher by over 1 mpg. I agree, with the MDS left engaged, most of the time, hand calculated mpg is a bit lower than that shown on the EVIC, but not always. A few times, with MDS left engaged, the hand calculated mileage was better than the computer generated number.
Also, as it is pertinent, my Ram has 3.92 gears. RPM while cruising on the high way is around 2000 with speeds in the 70 to 75 mph range.
And because another member posted about the ECO light, with MDS turned off, the ECO light never illuminates. With MDS left on, it does at various times, but I've no idea if that illuminated light means MDS operation, or just a high manifold vacuum condition, something economy lights only indicated on older vehicles.

My wife and I drive to the house we intend to retire in every two weeks, so yes, I will post my observed mileage after the next scheduled trip in two weeks. I now turn MDS off every time I start the vehicle and put it in drive. Vehicle operation is just so much nicer, tho I have to turn it off again after putting the vehicle in reverse and then back to drive. A tuner would solve that, but I can't justify the $$ (PCM & tuner).