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What is MDS
- Thread starter omalley72
- Start date
Nails
Ram Guru
Multi Displacement System- shuts 4 of the 8 cylinders down. Buy turn those cylinders injectors off and using solenoids to collapse the intake/exhaust valves
Edit: didn’t put in exhaust valves also
Edit: didn’t put in exhaust valves also
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Here’s a cool vid...
Nails
Ram Guru
All ram truck hemis have this system. As well as rest of vehicle line ups with them. Though I’m not 100% sure on hellcats or demons.
Reduce fuel consumption and add manufacture points for cafe/epa
Reduce fuel consumption and add manufacture points for cafe/epa
daberk
Active Member
Does anyone know if when MDS is active the same 4 cylinders fire all that time or are the 4 active cylinders rotated among the 8? From SpeedyVs video above it looks like each cylinder fires every other cycle when MDS is active (if my eyes are seeing it right).
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SD Rebel
Spends too much time on here
Just a note, your ECO light which corresponds to MDS being active is not on by default. You need to activate the ECO light in the Uconnect setting screen, then you will see when MDS is active.
If you have a stock exhaust, it's almost impossible to know when it's on or off other than the ECO light turning on. If you have an aftermarket exhaust, you will tell when MDS is on because it will drone noticeable in the cab.
That's why a lot of us will turn off MDS by setting our gear limit selection to 8. I will give you all 8 gears like normal, but turn off MDS.
Helmetface
Active Member
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From my understanding, while the parameters that affect ECO mode and MDS are very similar (maybe identical even), the ECO light is not an indicator that MDS is active.
I could be wrong, but I have read this numerous times on these boards.
SD Rebel
Spends too much time on here
I wasn't sure either, but I heard the opposite on this forum.
But after my exhaust install, you know exactly when MDS is activated with the cab drone you get at 4 cylinders, it's extremely obvious. Every time my MDS turns on, my Eco light turns on. I have never seen my Eco light turn on without MDS activated.
From what I've personally seen and also heard from others on this forum, the Eco light is indicative of MDS activation.
Though I would like to see official confirmation, I haven't seen anything in the manual to state one way or the other. It could be possible that the Eco light will turn on without MDS activation, but I haven't seen a situation where that has happened yet. It should be noted my truck doesn't have etorque, which may have a component in those trucks where the light turns on without MDS.
Same as mine.
I have Borla Atak exhaust and it doesn't drone or make a horrible noise but you can hear the difference with the window open.
I'd initially been turning off MDS as I was worried about piston drag, I fuss less about it now.
ECO is MDS. ECO is cylinder deactivation.
I haven't heard any different until about the last 2 weeks and it stemmed from someone asking.
I have a 6.4l Hemi that ECO came on quite often. I have fuel level sensor failure and the check engine light is on and it will not go into MDS or ECO because just like using the +/- gear selector takes it out, so does a check engine light.
You will never have the ECO light come on unless MDS is active.
ECO is MDS. ECO light indicates 4 cyls are deactivated.
It means nothing else.
I would really like someone who thinks otherwise to show proof, but the 6.4L was designed solely to get MDS into a heavy duty. You will not see ECO on a 5.7 l HD because there is no MDS.
Sometimes you will not hear it go into or out of MDS, because that is why the Hemi got its last power bump and with the 2019 5th Gen it has active noise dampening to make it even more seemless
I haven't heard any different until about the last 2 weeks and it stemmed from someone asking.
I have a 6.4l Hemi that ECO came on quite often. I have fuel level sensor failure and the check engine light is on and it will not go into MDS or ECO because just like using the +/- gear selector takes it out, so does a check engine light.
You will never have the ECO light come on unless MDS is active.
ECO is MDS. ECO light indicates 4 cyls are deactivated.
It means nothing else.
I would really like someone who thinks otherwise to show proof, but the 6.4L was designed solely to get MDS into a heavy duty. You will not see ECO on a 5.7 l HD because there is no MDS.
Sometimes you will not hear it go into or out of MDS, because that is why the Hemi got its last power bump and with the 2019 5th Gen it has active noise dampening to make it even more seemless
Same 4 Cylinders
That's it for the owner's manual.
I have the stock exhaust and I can feel when the MDS turns on/off. There is a slight clunk felt when MDS turns off when I give it more gas. There is also a noticeable pinging/metallic sound when in MDS under slight load. I'm having the dealer check this out to see if it's normal when i go for an oil change later this month.
RavenHemi19
Member
Did you ever get any feedback on this issue? I think I might feel the clunk you are talking about.
Gunner69
Member
Wow, now that I think about it, I may have heard and felt the same thing...
Trooper4
Ram Guru
Try Google search. It's amazing.
en.wikipedia.org
media.stellantisnorthamerica.com
Multi-Displacement System - Wikipedia
Stellantis Media - Multi-Displacement System to Save Customers 60 Million Gallons of Fuel Annually
The Chrysler Group Multi-Displacement System (MDS) is a fuel-saving cylinder deactivation technology that is here today – customers get the power and capability of the HEMI® V-8 that they desire with an improvement in fuel economy of up to 20 percent.
Well you can't expect them to fit everything into just 690 pages.
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