Why on Earth do people want to disable MDS? (Hemi newb here)

[Brett A Landry]

I have a 2018 RAM 4x4 with the 5.7 and asked customer care about what exactly does tow/haul mode does and this is the answer I got.
Tow/Haul Mode
When driving in hilly areas, towing a trailer, or carrying a heavy load and frequent transmission shifting occurs, pressing the TOW/HAUL switch to select TOW/HAUL mode will improve performance and reduce the potential for transmission overheating or failure due to excessive shifting. When operating in TOW/HAUL mode, transmission upshifts are delayed, 8th gear overdrive is prohibited, the Multiple Displacement System (MDS) system is prohibited from cylinder deactivation, and the transmission will automatically downshift (for engine braking) during steady braking maneuvers.

 

[m25443]

Marie Les - Does Cafe' even include 2500/3500 trucks? If not, then your first point of meeting Cafe' reqs is not valid. If it does include 2500'3500, then we should start to expect other lightening approaches in the near future (more aluminum beds, less steel in heavy components, etc.).

 

[RLJ10X]

GM/Cadillac was doing multiple displacement engines in 1981.

Tell me when you think Dodge started.

 

[Marine Les]

Marie Les - Does Cafe' even include 2500/3500 trucks? If not, then your first point of meeting Cafe' reqs is not valid. If it does include 2500'3500, then we should start to expect other lightening approaches in the near future (more aluminum beds, less steel in heavy components, etc.).[/QUote
I don't think the HD trucks are part of the CAFE standards but that does not make my point invalid. The CAFE numbers are governed by a specific set of tests that some manufacturers actually have programed the computers to recognize the test and reduce fuel delivery to achieve higher numbers. Café standards are not the only reason for better mpg, customers want the best mpg they can get for their vehicles and will shop the all that fit their needs and choose according to need and taste. Manufacturers are going to great lengths to get better mpg because of demand and could do better without arbitrary standards. Free market solutions are the best way not government dictating results that give us MDS and fuel programming designed for a single test not the real world. Work trucks are exempt because it does not work for the needs. Imagine big long haul rigs forced to get unrealistic mpg and being fined for not getting those numbers and maybe you can see my point.

 

[Matts175]

GM/Cadillac was doing multiple displacement engines in 1981.

Tell me when you think Dodge started.

My X Father-in-law had that terrible terrible running car. He disabled that one too, and it ran perfect after that.

 

[Ratket]

I have a 2018 RAM 4x4 with the 5.7 and asked customer care about what exactly does tow/haul mode does and this is the answer I got.
Tow/Haul Mode
When driving in hilly areas, towing a trailer, or carrying a heavy load and frequent transmission shifting occurs, pressing the TOW/HAUL switch to select TOW/HAUL mode will improve performance and reduce the potential for transmission overheating or failure due to excessive shifting. When operating in TOW/HAUL mode, transmission upshifts are delayed, 8th gear overdrive is prohibited, the Multiple Displacement System (MDS) system is prohibited from cylinder deactivation, and the transmission will automatically downshift (for engine braking) during steady braking maneuvers.

And that’s not true. Those people just read from a scripted screen like any other help desk.

 

[heefageLA]

Im sure this has been said already, but I always disable it. Even though you are running half your cylinders when MDS is engaged, you are dumping Twice the fuel to those cylinders still operating... It kind of negates any fuel savings IMO... Ive actually studied my MPG with MDS on and off. I still get the exact same gas mileage either way.

 

[RLJ10X]

I just wonder how many miles you have to put on these trucks before all the "Fuel Saving Gizmos" like shutters, transmission heaters, mds actually pay for themselves. You know all that worthless crap cost several hundred dollars.

Then there's the worthless crap that didn't cost anything, like the lightweight car tires they put on these things, too tall gears, front end droop.

They make a damn good truck. But the sure manage to screw up some of the details.

 

[Wahrsuul]

And that’s not true. Those people just read from a scripted screen like any other help desk.

And I suppose Customer Care just makes this stuff up for fun? The script doesn't come from FCA? Just because they're reading it doesn't make it invalid.

 

[Lucy Girl]

Can someone tell me how to shut it off??

 

[Ohio5pt7]

Can someone tell me how to shut it off??

Put truck in drive click gear down. That will put you in 1st click gear up till it reads 8. Then go.

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[pacofortacos]

And I suppose Customer Care just makes this stuff up for fun? The script doesn't come from FCA? Just because they're reading it doesn't make it invalid.

And yet he is correct, customer care was incorrect on many points.

Tow/haul does delay upshifts to a higher gear by a little bit, does do an earlier downshift when decel or going down a hill, and CAN reduce shifting depending on conditions.

Tow/haul does NOT lock out 8th gear overdrive or disable MDS.

This is true at least on my 2016 and I am pretty sure the 18 is the same.

 

[Ratket]

Yes customer care releases the info they are given by FCa, and yes it’s wrong and right, we all know what is and what isn’t, Sadly people who do not know from experience just have to go with what they are told, untill they come on here and we all can help steer them in the correct direction.

 

[Lucy Girl]

Put truck in drive click gear down. That will put you in 1st click gear up till it reads 8. Then go.

Sent from my SAMSUNG-SM-G891A using Tapatalk

Thanks

 

[Lucy Girl]

Thanks

Also will that work with the 6 speed trans?

 

[DA Smith]

GM/Cadillac was doing multiple displacement engines in 1981.

Tell me when you think Dodge started.

The crap Cadillac did in 1981 was way different than what is used now. The so called 4 6 8 system they used was a complete joke and failure. Using cheap solonoid's that didn't work, discontinued after first year. Chrysler came out in 2005 with a system that workes well and in 2007 GM followed with a copycat system. The 1981 crap from GM don't count and they only came out with a system that worked 26 years later following behind Chrysler two years later.

 

[Ohio5pt7]

Also will that work with the 6 speed trans?

I think it does but don't quote me

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[Lucy Girl]

Thanks. No problem. I will try it.

 

[prohunter4]

The thing about the GM system is it will aid in the destruction of your transmission.

 

[Black W900]

The crap Cadillac did in 1981 was way different than what is used now. The so called 4 6 8 system they used was a complete joke and failure. Using cheap solonoid's that didn't work, discontinued after first year. Chrysler came out in 2005 with a system that workes well and in 2007 GM followed with a copycat system. The 1981 crap from GM don't count and they only came out with a system that worked 26 years later following behind Chrysler two years later.

I had one of those Cadillacs...I disabled the 4-6-8 within a month of buying the car.

I'm a big fan of stock trucks, I don't do "mods"....I also don't ever drive my truck without shutting off the MDS system.
It makes little to no difference in fuel efficiency and causes an annoying drag and drone when it goes from 4 back to 8 cyls.
It's a stupid feature that is forced on us by the EPA and their ridiculous fuel mileage standards.