Jeep Garage  - Jeep Forum banner

Why does MDS suck so bad?

14K views 69 replies 26 participants last post by  tyresmoker 
#1 · (Edited)
After 20,000 miles, I absolutely love my '15 SRT but really hate the MDS system. Yea I get that you can disable it with the flick of the shifter and yea I get that gov't fuel efficiency requirements put it there.

But at speeds under 60 and with frequent acceleration/deceleration, this vehicle can really drive like crap in normal mode. In fact, I've had passengers and friends I've let drive it ask me if something was wrong with the vehicle.

Do other performance SUVs have this system and if so is it better executed so it's not so noticeable? There has to be a better solution to the engine rumbling and feeling of slack in the drive train as MDS engages/disengages.


Sent from my iPhone using JeepGarage
 
#2 ·
MDS has always sucked going back to the introduction of the new 5.7 years ago.

I had a 07 Overland with the 5.7 with the MDS. It sounded like a helicopter. Same with the SRT now. I literally always put it in Sport mode. I wish it could engage as soon as I turn the Jeep on. lol

The MDS has never improved. :(
 
#4 · (Edited)
I live in north Jersey. Traffic and local roads don't always make over 60 possible. Trust me, I push the beast when I can but the reality is I have to drive alot of miles at slower speeds



Agree RP - I've been doing the same shifting into sport at startup.


Sent from my iPhone using JeepGarage
 
#5 ·
It's retarded and I hate it ! It feels like the car is being held back whenever MDS is active...no other car manufacturer has such a system I believe and Jeep would do well to get rid of it. No one buying an SRT gives a crap about fuel consumption anyway


Sent from my iPhone using JeepGarage
 
#8 · (Edited)
I can say in my experience, without doubt, that there is a delay in throttle response with MDS activated and as the MDS switches back off, especially around town. That seems to translate to a feeling of hesitation. It's not a huge difference, but I notice it particularly on part throttle acceleration.

In saying that, I drive with S selected on the trans almost exclusively. So the few times I've forgotten to flick the lever off D on start-up, and with the softer, slower shifts it has, makes it seem worse than I'm sure it would be, if I normally drove in D only. But it's definitely there.
 
#11 ·
First thing I did for my old MY13 was to purchase a tuner, turn off MDS and get a custom tune. But given the small gains unless you are modifying a number of items on the MY15, seemed a bit over the top to buy a new ECU (if that's still a thing), and then a tuner for the MY15, just to remove MDS. Flick of the wrist into S on start-up and problem solved. :)
 
#17 ·
Hmmm. Jeeps must be set up different then, because I've never felt anything like that. Though as mentioned, the audible tone of the exhaust is noticeable. Guess you gotta get a tuner to disable it, or keep using sport mode.
 
#21 ·
I don't think I'd call it garbage. Like I said, I've never been able to feel it, and I've had several Rams, and a Chargers with it. Not trying to say it isn't poorly implemented in the Jeep though, since I have no experience with it in GC. Since the mechanical system is the same between the Dodge and Jeep, I'd assume the "garbage" is computer controlling it. I wouldn't be too surprised to find that it's the same computer too, just programmed different. From the sounds of what you guys are saying, it seems the Jeep is taking too long to reactivate the extra 4 cylinders when you need the power.

And by the way, Yeti is correct on the acronym.
 
#22 · (Edited)
In my experience it is very inconsistent. Sometimes I don't notice it. Other times it feels like it is in too low a gear. The engine rumbles and vibrates and I feel a real heaviness in the drivetrain before the other cylinders engage.

Most likely software is to blame.


Sent from my iPhone using JeepGarage
 
#25 ·
I think the big question is do you see anything gained from MDS? And I would say only benefit is to decrease fuel consumption.....
Correct, that's the only benefit of the system. It isn't doing, or trying to do, anything other than save fuel.
As for my savings, I notice about about a 3 mpg improvement in the Ram with it on. The Charger is around 5 mpg better with it on. Neither of those are ground breaking improvements, but I suspect they would be slightly higher if I drove long stretches on the interstate where going to 4 cyl mode really makes a difference. Also as you mentioned, driving habits certainly play into it. If someone is hammering the gas to get it out of MDS, they're likely going to use more fuel during the brief WOT blast than they saved by having 4 cylinders shut down for 1/2 mile or something.
You can feather/baby a Hemi to get it to produce some pretty good MPG numbers, but then none of us have bought a V8 to hypermile it.
 
#24 ·
IDK if it because I have a 14', or the mods (aFe intake/Corsa full cat-back), but I am at 21k miles know and it has been running amazing! I used to notice it more before I switched to Mobil1 oil...that was about 8k ago...plus I have Toyo non runflats...which may help a little.

I could not be happier with how it drives...hope it stays that way. No issues with MDS; ONLY thing I notice is a 55-60 weird "lag" sometimes when I have been babying the throttle. Otherwise with spirited driving, or Sport Mode as Robert Palmer said appears to eliminate it for my driving: around town and 10+ mile freeway trips weekly 65-80mph
 
#29 ·
I knew the truth but you served yourself up commenting on MPG and SRT in the same convo... :thumbsup:

i, too, get great mpg on highway trips with my human nanny, the Mrs., on board...once in a while she grins while she is shrieking :cool:
 
#31 ·
I prefer MDS. There are times I granny the Jeep for MPG's (highway driving more than anything - but sometimes if I am not in a hurry). It makes up for all the WOT runs I do, which is almost certainly every time I drive it. :)

There is a slight hesitation that can be felt when it is on the verge of wanting to stay in 4 cyl and jump into 8 cyl. And at highway speeds I can feel it lurch forward during the transition where it gets the extra power. Since I have redone the full exhaust, passengers quickly noticed when the transition occurred at freeway speeds and asked if something was wrong. With a full exhaust, the engine lets out a, sometimes, very loud grunt when it kicks into 8 cylinders. Just depends on the speed and required throttle increase, but it is really noticeable in my SRT with the mods. I don't mind it one bit though.
 
#32 · (Edited)
Just an update here.

After doing some more research, I came across suggestions to do a "throttle calibration" to smooth out the lag of MDS. While throttle calibration is a known procedure for many vehicles, there seemed to be a lot of back and forth over whether it actually works for the WK2. However, quite a few owners reported it very effective and it is a simple procedure so I figured I'd give it a try.

According to what I found, you put the vehicle in run mode --- without the engine on. After the warning lights disappear you slowly depress the gas pedal to the floor and release three times. Then hit the push button to off.

I don't truly know if this did anything but I can say that my throttle is significantly more responsive and MDS is nowhere near as noticeable or clunky. It is really a night and day difference.

Anyone else ever hear or know more about this?


Sent from my iPhone using JeepGarage
 
#33 · (Edited)
Well I hate to be the barer of bad news, but that's not doing a throttle callibration. All you just did was reset your Oil Change Indicator. Your computer tracks duty cycle (time on, throttle positions, etc) to determine the life of the oil. The system tracks when you should change the oil based computations related to your specific use. When it's time for an oil change the light turns on telling you it's due. Once you change the oil, you perform the above cycle, and it restarts tracking the life of the new oil.

This has been how you reset the oil life indicator for years now on Dodge and Jeep vehicles equipped with it. For further it should be in the area of page 298 of your owners manual.
Though the mentioned perception of increased throttle response, and decreased lag tells me there was a definite placebo affect. Which further tells me that the MDS transition may not be as bad as assumed, but when you're "searching" for it, it's much more obvious. IDK, just kinda spit-balling here.
 
#34 ·
Lol who knows?!! The Internet is full of good and bad info!! I don't use the oil change indicator anyway. I go by miles and it's fairly easy for me to remember!

Regarding MDS, I have no idea. I'm not the kind of person who goes looking for things wrong but trust me there was no missing it. Sounded and felt like the vehicle was in the wrong gear.

Anyway I'm just gonna continue to slap it into sport and enjoy the hell out of it!!


Sent from my iPhone using JeepGarage
 
#41 ·
I have about 1000 miles on my new 2017 SRT and I love, what a great car! But I started noticing some weird things...
When I drive at around 55 mph in 8th speed at about 1500 rpm the car starts vibrating , so much that rattles are coming out of everywhere.
On the highway if I use the acc, which I loved in my Overland , I can feel the Jeep launch forward every time the 4 cyl light goes off, and I clearly hear the engine change. When the 4 cyl light is on it feels like I'm in a small plane because of the noise!! The noise and vibrations instantly disappear when push the gear shifter in sport and the engine is smooth as silk.
Is there something wrong with my car or is it just the mds system that is crap?? My 2005 Hemi had mds and I could hardly feel it coming on or off.
 
#44 ·
To slow the car down the ACC will downshift. That causes the engine speed to increase which shuts off the MDS. Next time it happens check the speedometer and the tach. You may find the tach is up and it is you lurching forward, not the Jeep.

As for the noise, that is a known issue. I know the Summit has noise cancellation technology built into the sound system for this purpose.
 
#46 ·
Heres what I do. Start off in Sport mode through the first 4-6 gears, slap it into Drive mode to get into 7th/8th and then slap it back into Sport. Mine holds 8th gear in Sport mode and I cant say Ive ever felt MDS kick on
 
#47 ·
Thank you for your responses, but Bill the transmission does not downshift everytime mds goes off, it does not explain the surge in power every minute to ajust to the speed of the car in front ouf me. This system is suppose to go from 8 to 4 cyl and back depending on driving conditions without the driver noticing it, at least not that much. I've seen it work in a Hemi 5.7 and if the radio was on I could not notice it. And from the responses of other owners it seems everyone has figure out a way to go around it in sport mode... which will have exactly the opposite effect it was designed for: save fuel. I cannot beleive engineers drove this and decided it was ok. But hey, this car in sport mode is FANTASTIC to drive!
 
#49 ·
Thank you for your responses, but Bill the transmission does not downshift everytime mds goes off ...
But MDS shuts off when the car downshifts. Any time the engine speed increases more than the slightest bit, all 8 cylinders kick in. I think you have the cart in front of the horse.

--
 
#48 ·
You can thank the greenies for MDS.
Chryslers version of Volkswagon software.
With retuned cam timing etc, and MDS off, I get 10% better mpg than OE.
Even with a supercharger it is 8-10% better.
NOX is probably not good tho and that is what the greenies get upset about.......
But I just hate the NVH that comes with MDS most of all.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top