Was concerned about MDS ("Multi Displacement System") in my DSRT 392 ... not anymore!

[SilverBillet]

Good point with the metallurgy comment, looking at my failure and seeing "wear" failures for a bearing surface, or multiple bearing surfaces (needle bearings and trunnion) in my case is concerning from a part spec requirement standpoint, meaning it points to a design failure or heat treat failure where lubrication is actually present in sufficient quantity.

What I said…

 

[Hamsquatch]

Thanks OP I never really thought about it too much. I guess I always figured - maybe incorrectly? - that when it's placed in Sport or Track in the Performance Pages it turns it off. But I guess this is not the case? Again, I thank God she runs great and jumps when asked, so I've never really dwelled on its operation.

 

[ScottsSRT392Durango]

Excessive idling seems to be a common cause if failure, as does using the wrong oil. I have 449,000 miles on my Ram with the 5.7 and MDS. I wish I had a nickel for every YouTube genius with a theory and another nickel for everyone that believed them.

Just keep the vehicle in Sport or Track mode. MDS is turned OFF in BOTH of these modes.

 

[drag racer]

MDS does nothing and its a waste. After deleting it I noticed 0 mpg difference yes 0. Its just a sham!

I agree 100%, and if I ever have to tear into the top half of either of mine they will be gone and deleted. It is nothing but an expensive, overly-complicated system that adds nothing to vehicle mobility or performance, except bow to liberal retards.

 

[RetiredFirefighter]

So maybe in summation, it's like with every vehicle ... some are made well and some not so well.

 

[GNBRETT]

Is getting a bad lifter after 144,000 miles really that bad/unexpected?



So from what I'm seeing people reporting here, with good maintenance my 392 should last 100,000-150,000 miles before any lifter/cam issues.

Up until then, I purchased Dodge's 100k extended warranty so I have that.



I haven't done a thorough test yet, but so far it seems MDS nets me another 2.5 mpg (from ~15 mpg to 17.5 mpg).

If that is the case and I drive ~12,000 mi/year, that works out to a monthly fuel savings of ~$40 month.

Negative. Its does nothing! Another 2.5 mpg lol thats a pipe dream bro not happening...... Its literally less thgan 1 mpg if that.

 

[drag racer]

I have done a lot of observing of this system in my DSRT on highway drives. Usually, I can feel it go on and off, but sometimes it is subtle if the road is rougher. Anyway, if you tune the center stack to the fuel economy page, you will see the light to know for sure when its on or off. I have found that when it comes on at the speeds I usually cruise at like 80-85 out on the open road, it doesn't take but a hint of throttle to either accelerate slightly, or when the elevation goes slightly uphill, to turn it off.

My conclusion is, having the system on board helped Dodge during their certification testing in controlled environments get some kind of brownie points with the fed's. But in the real world, unless you are travelling in super flat terrain at a speed low enough to keep it on for a long time, I doubt it is helping mpg a whole lot. I could be wrong, but I agree with Brett that if you get +1 mpg out of it, you're doing great. Not to mention the nausea I feel when I feel it going on and off, on and off, ... just thinking about the 4 lifters locking pins and springs and the solenoids just cycling away their life and wondering how long I'll get until the system takes a dump on me at an inopportune time and I have to teardown the top of the engine to fix it all... And any money in gas saved over the life of the system until it fails will likely be small in comparison to the cost to fix or get rid of it.

 

[RAMBLE1]

Just keep the vehicle in Sport or Track mode. MDS is turned OFF in BOTH of these modes.

I found another way to block out the (Hemi) MDS. Start, put in D and then, tap the "GEAR-" button, then tap the "GEAR+" button to gear "8" or what ever gear you want. This will keep the MDS from engaging. I do this every time the Ram is driven. I have done this on my last three Rams and Ram Classic and works like a charm. I received this advice years ago, when I was purchasing my first Ram with MDS. Also, was told, this will be much better for the engine and transmission and will avoid many problems after 100,000 miles. I noticed the transmission doesn't bounce from gear to gear, and is much smoother. Glad I listened.

 

[RAMBLE1]

MDS does nothing and its a waste. After deleting it I noticed 0 mpg difference yes 0. Its just a sham!

I agree with you. I tried the MDS on my Ram Hemi on short vacation and around the house for a little while. There was no difference! I went back to blocking out the MDS and my truck runs better, the transmission isn't continually jumping in and out of MDS mode. That is the first and last time I will use MDS.

 

[DGatzby]

I hate it on the 392. It certainly “grinds” and has an awful vibration sometimes at low speeds. Won’t be too long and they can have their warranty shit, I am about to rip out the ECM and have my good buddy fix this bitch to run correct. Besides the tune $$ and ECM unlock $$ the rest of it will be an easy addition using HP Tuners etc.

@RAMBLE1 I will try your suggestion next time I drive it. I have been just switching to Custom mode and keeping everything the same except tranny. Double enjoyment in town use it in Sport or Track tranny and screw the MDS.

 

[RetiredFirefighter]

Negative. Its does nothing! Another 2.5 mpg lol thats a pipe dream bro not happening...... Its literally less thgan 1 mpg if that.

Well, it's what I noticed when I tried it that one time. It wasn't a real "back-to-back" extended test or anything.

So I just checked a few YT vids where owners tested the MDS, and it seems you guys were right.

This guy only gained ~1/2 mpg with MDS on:

This guy actually got better mpg with MDS OFF!

 

[DGatzby]

Well, it's what I noticed when I tried it that one time. It wasn't a real "back-to-back" extended test or anything.

So I just checked a few YT vids where owners tested the MDS, and it seems you guys were right.

This guy only gained ~1/2 mpg with MDS on:

This guy actually got better mpg with MDS OFF!

Not surprised. I know while it is grinding etc. and it don’t matter hitting Sport in a 5.7 Grand or hitting custom on the Durango, when it stops, I can lift the throttle just a bit.

 

[2ndAmend]

Different but somewhat related topic, and I want to bitch about stellantis!

I ordered a M6 in my ’24 Wrangler, and I think I found out why you never see them on a dealer’s lot. The engine hesitates, then stumbles, pulling then hesitating, so badly that sometimes it is a “bump”. Dealer did nothing.

I contacted Jeep and they sent a rep to the dealer to check. He drove similar Jeeps and reported it is a characteristic of all of them. Serv advisor said it is the variable valve timing. Apparently it can’t make up it’s mind and stellantis (Jeep Cares) couldn’t care less. Apparently the A8 masks the prob.

I would dump it in a sec if there was a competitive product, but they sure have that niche locked down. Besides, my wife loves her Jeep. I often think maybe I should have kept the rusted out TJ.

I mailed a letter to Antonio Filosa, COO North America, CEO Jeep, on Dec 6 politely detailing my frustration, have not heard back yet…

What we have here is overbearing gvt forcing mfr’s to make simple things unnecessarily complicated for questionable gains. In the process, drivability, initial cost, long term cost, and reliability all suffer. Thanks FJB!!!

Every politician in DC needs to experience the impact of their work, make them, and all of their aids/staff buy and drive EV’s only! And include Secret Service, police, ambulances, and all Fed agencies! But NOOOO! It is ALL for THEEE, and NOT for the anointed!!!

Thanks for letting me rant!

 

[RetiredFirefighter]

Not surprised. I know while it is grinding etc. and it don’t matter hitting Sport in a 5.7 Grand or hitting custom on the Durango, when it stops, I can lift the throttle just a bit.

What gets me is the time, effort and $$ that CDJR put into the MDS system ... and it doesn't actually help that much.

Was 1/2 mpg worth all that? Why the smoke in mirrors?

 

[Unholy707]

I have done a lot of observing of this system in my DSRT on highway drives. Usually, I can feel it go on and off, but sometimes it is subtle if the road is rougher. Anyway, if you tune the center stack to the fuel economy page, you will see the light to know for sure when its on or off. I have found that when it comes on at the speeds I usually cruise at like 80-85 out on the open road, it doesn't take but a hint of throttle to either accelerate slightly, or when the elevation goes slightly uphill, to turn it off.

My conclusion is, having the system on board helped Dodge during their certification testing in controlled environments get some kind of brownie points with the fed's. But in the real world, unless you are travelling in super flat terrain at a speed low enough to keep it on for a long time, I doubt it is helping mpg a whole lot. I could be wrong, but I agree with Brett that if you get +1 mpg out of it, you're doing great. Not to mention the nausea I feel when I feel it going on and off, on and off, ... just thinking about the 4 lifters locking pins and springs and the solenoids just cycling away their life and wondering how long I'll get until the system takes a dump on me at an inopportune time and I have to teardown the top of the engine to fix it all... And any money in gas saved over the life of the system until it fails will likely be small in comparison to the cost to fix or get rid of it.

What does the light look like when it kicks in? I thought this only kicked in while in eco mode?

 

[MikeD1]

What does the light look like when it kicks in? I thought this only kicked in while in eco mode?

That is true for the R/T's - you press the ECO button and it's off (even thru stop/start cycles) till you press the button again.
With the DDSRT's it's on unless you put the car in Sport or Track mode (which gets reset in the stop/start cycle).

 

[drag racer]

What does the light look like when it kicks in? I thought this only kicked in while in eco mode?

I think it says "4 CYL MODE"...blue light (?), right in the center of the center stack

 

[DGatzby]

I know it does if you watch the gas mileage screen.