Jebb
Senior Member
- Joined
- Aug 22, 2017
- Posts
- 127
- Reaction score
- 65
- Ram Year
- 2017
- Engine
- Hemi 5.7
I was surprised to find out that my 2017 Hemi QC has "MDS". I thought they got rid of that when they went to variable valve timing.
I have been experimenting with MDS off (8th gear trick) and can really tell the difference in sound and feel when MDS is turned on/off.
Surprisingly, I am seeing NO DIFFERENCE in mpg with it turned off. In fact in my truck (3.21 gears and 35" tires) it seems MDS struggles - it's too low of gear and too much tire for a "4 cylinder". Sounds like it's bogging when on. Works OK at 70mph on flat ground but kicks out then causes downshift on the slightest grade. Runs better overall with it off.
Why does an engine with VVT even NEED MDS?
I have been experimenting with MDS off (8th gear trick) and can really tell the difference in sound and feel when MDS is turned on/off.
Surprisingly, I am seeing NO DIFFERENCE in mpg with it turned off. In fact in my truck (3.21 gears and 35" tires) it seems MDS struggles - it's too low of gear and too much tire for a "4 cylinder". Sounds like it's bogging when on. Works OK at 70mph on flat ground but kicks out then causes downshift on the slightest grade. Runs better overall with it off.
Why does an engine with VVT even NEED MDS?