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2018 Challenger 392 R/T Scatpak
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Discussion Starter #1
Hey guys, Im new here and just made the jump from a 2017 R/T 5.7 to a 2018 R/T scatpak 392, both of which have MDS. What I noticed and am concerned about is that the 5.7 was much more MDS friendly, in the sense that it would engage as soon as it could and stay on for as long as possible. The 392 on the other hand rarely ever engages MDS, even when it does, all it takes is the slightest press on the throttle to disengage it. I know MDS isn’t a desirable feature for most people here, but I use my car as a daily driver and can benefit from even the smallest gains in fuel economy. My questions are:

1) Is this a sign of the MDS failing or is it normal?

2) How should I look out for now that I own a 392? (What are some common failures and problems with the engine or trans)

3) I’ve read on many places that the 6.4L is much more reliable compared to the 5.7L, is this true?

My vehicle is a salvage but was repaired to factory specs, it has 15K miles on it. Thank you!!
 

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2018 Scat Pack SHAKER in Plum Crazy
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The thing with going from a 5.7 to 6.4 with MDS is the additional torque. (I went from a 2015 Charger R/T R&T to 2018 Scat Pack Challenger)
The MDS kicks in on the 5.7 when you are low throttle for a few seconds and under about 95 Torques, and kicks off when you demand about 120.
With the 6.4 instead of running low throttle opening, it can kick up another gear and still have enough torque at the low rpm to run fine. Running a large engine with tiny throttle openings is what kills efficiency, "pumping losses" with the engine trying to suck air, but isn't allowed to. With low RPM, and open throttle, the engine is very efficient, more than running in a lower gear with MDS enabled.
Being in SW PA, we have every type of terrain, every single mile on every road, so I see the engine doing everything. If you pull up performance pages and watch the torque when it kicks in and out, you will get an idea, and can actually drive in the sweet spot if you want to.
 

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2015 RT 5.7 M6
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From what I have read, signs of MDS lifter/cam failure are misfire or air/fuel ratio imbalance DTCs that pop-up on the same cylinder or bank.
 

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2019 Challenger Scatpack
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Being new here I have done tons of catch up reading on old threads. And the MDS has as many different opinions than the subject of oil does.. I personally do NOT like it and after reading which models do what in sport mode, I went out and played some with mine and I found out my 2019 SP mds does in fact not kick in while it is in sport mode ! What a pleasant surprise. I would rather pay the difference in a little fuel than to be bothered with the MDS mode.
I have found that in auto mode it is hard to figure out when or how MDS works, it never seems to do the same thing as a routine. Seems like in a perfect world MDS would have had a on/off switch and operate at the pleasure of the owner. Just my 2 cents worth on MDS
 

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2016 SXT Plus Blacktop
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In Televisions, to get the Energy Star rating, the TV needs to default to whatever Eco mode the manufacturer used to achieve the rating. But they give you the ability to turn it off in the menu

Since MDS has to do with CAFE standards, and is much more than just a rating, having the ability to just switch it off wouldn't fly. BUT, in a way Dodge has provided you with an off switch (Sport mode), you just have to switch it every time you start the car ;)

A Guy
 

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The thing with going from a 5.7 to 6.4 with MDS is the additional torque. (I went from a 2015 Charger R/T R&T to 2018 Scat Pack Challenger)
The MDS kicks in on the 5.7 when you are low throttle for a few seconds and under about 95 Torques, and kicks off when you demand about 120.
With the 6.4 instead of running low throttle opening, it can kick up another gear and still have enough torque at the low rpm to run fine. Running a large engine with tiny throttle openings is what kills efficiency, "pumping losses" with the engine trying to suck air, but isn't allowed to. With low RPM, and open throttle, the engine is very efficient, more than running in a lower gear with MDS enabled.
Being in SW PA, we have every type of terrain, every single mile on every road, so I see the engine doing everything. If you pull up performance pages and watch the torque when it kicks in and out, you will get an idea, and can actually drive in the sweet spot if you want to.

Sounds like normal operation for the MDS on the 392.

Personally, I run in Sport Mode all the time. I lose only 1.5 - 2 mpg's, but the car is more responsive, no 4 cylinder vibration, and I don't have to listen to that 4 cylinder exhaust tone.
 

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I can't tell when my 18 Scat Pack is in MDS mode unless I pull up the MDS gauge. The transition is seamless between 4 cyl. MDS mode & the 8 cyl. mode.
 

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There are times when I'm cruising on the highway at a constant speed and don't want the loud exhaust noise either cause I'm talking to someone or listening to music. MDS exhaust note is definitely much quieter in most speeds and is welcome in those situations.
 

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2019 Challenger Scatpack
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I can't tell when my 18 Scat Pack is in MDS mode unless I pull up the MDS gauge. The transition is seamless between 4 cyl. MDS mode & the 8 cyl. mode.
The flutter of the MDS kind of reminds me of a carb with a plugged up jet until it makes the transition. I have read all sorts of what modes it works, and what modes it don't work in. But I know for a fact my 2019 Scat MDS does not engage in sport mode, and the other day just playing with things in regular street mode in M shift it never engaged one time. Back in auto mode it works as it should. If I did more highway miles it would probably be less annoying but most of my driving is around town.
 

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2015 RT 5.7 M6
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Sounds like MDS on the challenger is really annoying...on my 2013 5.7 JGC all you feel is a slight increase in vibration, change in exhaust note is hardly noticeable.
 

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2018 Scat Pack SHAKER in Plum Crazy
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Sounds like MDS on the challenger is really annoying...on my 2013 5.7 JGC all you feel is a slight increase in vibration, change in exhaust note is hardly noticeable.
Yes it does, sound like it, on the internet, from people that notice it.
But actually, NBD. It was basically transparent on my 2015 Charger R/T 5.7, and you can tell on my 2018 6.4, but it isn't bad, just noticeable. And with the louder/free flowing exhaust, you can hear it over road noise at slow speeds. Personally I'm impressed when it can cruise along in 4cyl mode. Then again, it is a 3.2 liter 4 cyl! I wish you could "lock" it into 4cyl mode to keep it there longer and force it back quicker.
 

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Lol, lock 4 cylinder mode. Reminds me of thoughs old Gordon Smith 460 BBF air units that ran 1 bank as a 4 banger and the other bank had a special head that was the compressor. If you did not have it hitched behind a vehicle that dam thing would hop around the job site. Can't believe they would do the same with Model A motors (2 cylinders were the compress and the others internal combustion).
 

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Just me, but when the MDS activates, the exhaust sounds like crap at any speed/RPM.

It's this way on my 392, and it was the same way on my R/TC.

Just a low pitched groan.

"Look away, I'm hideous."
 

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2018 Scat Pack SHAKER in Plum Crazy
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Lol, lock 4 cylinder mode...
Yep, would be nice, for when on the up and down crests of hills where you hit a dip just enough to kick it out of MDS, and a few seconds later, it is back in. Maybe call it "ECO Plus" or something where it is very aggressive in enabling MDS. Also I wish you could turn off, even momentarily, auto braking under cruise control, for those same scenarios with up and down small hills. Mine auto brakes in normal or adaptive cruise.
 

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Barely notice MDS. Exhaust note changes, mileage increases. That's about it. Kicks off if I want to accelerate or in manual. I set up a custom mode that is basically a street sport mode. That's good for cruising without MDS, but honestly I hardly notice it.
 

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987156


A Guy
 

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They were thinkin' though!

A Guy
 
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