MDS question

[Hangman]

Sorry if it’s been covered, did a search but didn’t see what I was looking for.

Why do I see everyone looking to disable the MDS in their trucks?

I haven’t received mine yet so I really have no dog in the fight per say. So curious as to the reasons to disable.

 

[LateToTheParty]

There is a handful of reasons.

At one time there was some internet lore that tied lifter failure to MDS equipped engines. I believe that was mostly squashed when data pointed to failures beyond the MDS equipped engines and many times pointed to usage of the wrong oil.

Some who really care about the sound of their exhaust don't like the change in tone/volume when it kicks in.

Some don't like the momentary "lag" when in MDS mode and wanting/needing to jump on the throttle.

Personally, I don't ever purposely try to deactivate it, but I do limit my gears quite a bit while I'm up and down in the mountains, so it gets turned off in those situations, but not specifically because of MDS.

 

[Hangman]

There is a handful of reasons.

At one time there was some internet lore that tied lifter failure to MDS equipped engines. I believe that was mostly squashed when data pointed to failures beyond the MDS equipped engines and many times pointed to usage of the wrong oil.

Some who really care about the sound of their exhaust don't like the change in tone/volume when it kicks in.

Some don't like the momentary "lag" when in MDS mode and wanting/needing to jump on the throttle.

Personally, I don't ever purposely try to deactivate it, but I do limit my gears quite a bit while I'm up and down in the mountains, so it gets turned off in those situations, but not specifically because of MDS.

Very good job explaining it. Thank you

 

[mountainears]

I’m in the Corvette world as well. In that space, there are some suspected issues that are related to it with regards to transmission issues. As a result many folks thought that by disabling it (Range makes an OBD device that kills it) then you would eliminate the issue. Not sure it has been totally proven but the mindset has stuck in that community.
Additionally, many did not by a Corvette for fuel economy reasons, they want performance all the time. I’m guessing this may be more of the thinking here.


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[Poolmonkey]

I didn’t like it at first, hardly notice it now

 

[jsalbre]

I find it funny that people complain about lag from MDS as the transition time between modes is about .04 seconds at 1500 RPM and even quicker at higher engine speeds.

 

[Greenhills]

it's pretty noticeable with certain aftermarket exhausts. I have a flowmaster muffler, with the resonator removed (exhaust dumped at the axle) and it sounds great until the MDS kicks in. So i turn mine off every time i get in the truck.

 

[Dave01]

I definitely notice it, don't mind it at all. As jsalbre said the lag time is a non factor. A thank you to Ram for putting an indicator light on the dash, even though it's easy to hear I like having the indicator too.

GM in the 2010's had a very real MDS lifter failure issue on 5.3's. I had a few and thankfully didn't have it, was very careful about oil change intervals (3000 miles) and oil used. That kind of tainted other manufacturers by association, but to my knowledge Chrysler has had no issues.

How much does it gain us in mpg? Can't amount to much. Maybe if you drive with a light foot and no towing you can get 1 or 2 mpg, not sure, but in my driving I'd be shocked if I get more than half a mpg from it, and when you think about all the mechanical parts and complication it just doesn't seem worth it.

 

[jsalbre]

I definitely notice it, don't mind it at all. As jsalbre said the lag time is a non factor. A thank you to Ram for putting an indicator light on the dash, even though it's easy to hear I like having the indicator too.

GM in the 2010's had a very real MDS lifter failure issue on 5.3's. I had a few and thankfully didn't have it, was very careful about oil change intervals (3000 miles) and oil used. That kind of tainted other manufacturers by association, but to my knowledge Chrysler has had no issues.

How much does it gain us in mpg? Can't amount to much. Maybe if you drive with a light foot and no towing you can get 1 or 2 mpg, not sure, but in my driving I'd be shocked if I get more than half a mpg from it, and when you think about all the mechanical parts and complication it just doesn't seem worth it.

It’s hard to quantify an exact MPG gain from it as that’s going to depend entirely on how and where you drive. If you spend a lot of time at highway speeds on flat ground you’ll probably see a lot more improvement than someone driving in the mountains.

The technical reviews of the Hemi MDS system say it uses about 20% less fuel when it’s engaged.

 

[Rockcrawlindude]

I don’t like it mostly because of the sound at low speeds. I have an issue that happens frequently to me.

Leaving my neighborhood around 20mph slightly uphill it will go into MDS right after the same left turn up the hill to get out. At that low speed it lugs and doesn’t sound great and I don’t want to use enough fuel to bring it out of MDS because I am in the neighborhood.

Here is the real problem: i have two buddies that live right there and one is a race car guy the other is a truck guy. Car guys like to be out in the garage. I’m a man and I can’t stop being a man. I can’t let my truck sound like that driving past those guys. So I disable it

So I disable it every time I get in the truck, typically. I might let it come on when/if I get on the highway because it’s surprising that it’ll be in MDS at 80mph cruise control.

 

[Dave01]

How do you disable it?

 

[Rockcrawlindude]

How do you disable it?

Either push the gear +/- button or use tow/haul mode. I usually use the +/- button and just set it to 8

 

[jetrinka]

I don’t like it mostly because of the sound at low speeds. I have an issue that happens frequently to me.

Leaving my neighborhood around 20mph slightly uphill it will go into MDS right after the same left turn up the hill to get out. At that low speed it lugs and doesn’t sound great and I don’t want to use enough fuel to bring it out of MDS because I am in the neighborhood.

Here is the real problem: i have two buddies that live right there and one is a race car guy the other is a truck guy. Car guys like to be out in the garage. I’m a man and I can’t stop being a man. I can’t let my truck sound like that driving past those guys. So I disable it

So I disable it every time I get in the truck, typically. I might let it come on when/if I get on the highway because it’s surprising that it’ll be in MDS at 80mph cruise control.

LOL I do the same thing when driving down the Main Street of our small town past all the bars at night hahaha!!! It makes an embarrassing noise for sure

 

[Dave01]

Either push the gear +/- button or use tow/haul mode. I usually use the +/- button and just set it to 8

Thanks, I knew tow/haul disabled it but didn't realize locking in 8 did so. Good to know.

My Durango has the "eco" button, when that mode isn't on MDS is still active but rarely comes on.

 

[JimKIII]

I always disable it because of the low vibration/rumble it causes when MDS engages. I'm told over and over that the engineering is exact and there are no problems and no wear and tear on the engine when four of eight cylinders go offline. But the low vibration it creates just annoys me. To me it's just another bunch of crap designed into these engines to appease the doom-and-gloom climate screamers. It's like all the starters you hear crank on at every stop light now. A friend of mine who owns one of those cars say his starter engages over 3 dozen times to get to work (he drives through a major city with lots of lights), where previously it only did it once where leaving the house. Seems to me the percentage of burned out starters needing replacing in a year or two is going to sky rocket. I guess we'll see about MDS engines being foolproof as time goes on and mileage piles up.

 

[Jimmy07]

I guess we'll see about MDS engines being foolproof as time goes on and mileage piles up.

I would think 16 years of MDS being implemented in Ram trucks (8 years for the 6.4 hemi specifically), and all the myths of it being bad for the engine having been debunked would be enough…

 

[jsalbre]

I always disable it because of the low vibration/rumble it causes when MDS engages. I'm told over and over that the engineering is exact and there are no problems and no wear and tear on the engine when four of eight cylinders go offline. But the low vibration it creates just annoys me. To me it's just another bunch of crap designed into these engines to appease the doom-and-gloom climate screamers. It's like all the starters you hear crank on at every stop light now. A friend of mine who owns one of those cars say his starter engages over 3 dozen times to get to work (he drives through a major city with lots of lights), where previously it only did it once where leaving the house. Seems to me the percentage of burned out starters needing replacing in a year or two is going to sky rocket. I guess we'll see about MDS engines being foolproof as time goes on and mileage piles up.

MDS is to save you gas and money (and by saving fuel helps the manufacturer meet fleet economy standards). For an HD engine it’s not even helping the company as fuel economy numbers aren’t published. It’s strictly to save you gas. It’s not some vast conspiracy.

Start-stop is the same way. The starters used in start-stop systems are engineered much differently than “normal” starters and will likely outlast a standard starter in a non-stop start vehicle. Aside from better engineering of the starters themselves the computer actually knows the exact position of the engine when it stops, including which cylinders have fuel in them and which spark plug fires next. This allows the starter to run for a much shorter time to restart the engine. They’ve been using them in European vehicles for more than 20 years without issue.

 

[jetrinka]

I would think 16 years of MDS being implemented in Ram trucks (8 years for the 6.4 hemi specifically), and all the myths of it being bad for the engine having been debunked would be enough…

This. Exactly

 

[JimKIII]

MDS is to save you gas and money (and by saving fuel helps the manufacturer meet fleet economy standards). For an HD engine it’s not even helping the company as fuel economy numbers aren’t published. It’s strictly to save you gas. It’s not some vast conspiracy.

Start-stop is the same way. The starters used in start-stop systems are engineered much differently than “normal” starters and will likely outlast a standard starter in a non-stop start vehicle. Aside from better engineering of the starters themselves the computer actually knows the exact position of the engine when it stops, including which cylinders have fuel in them and which spark plug fires next. This allows the starter to run for a much shorter time to restart the engine. They’ve been using them in European vehicles for more than 20 years without issue.

Ok Ok..... I still don't like the low rumble and vibration and no amount of saving gas is going to change that.

 

[jetrinka]

Ok Ok..... I still don't like the low rumble and vibration and no amount of saving gas is going to change that.

I agree I don’t like it either. I’ve gotten used to it for the most part though