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MDS

Sorry you all are having issues. After about 6K mikes and varied driving/towing I can’t feel MDS at all. Either the 19 PowerWagon’s ATM is really performing, my butt is numb, or my MDS is working as designed. [knocks on wood]
 
MDS cuts off 4 cylinders. In my truck, it makes a very, very slight vibration. I usually don't notice it, guess I tune it out. Plus I can feel a slight power lag of about 1/4 second sometimes if I try a hard, sudden acceleration when the MDS is on. It's very much like driving some cars with turbos and feeling the boost lag. But it's not so noticeable if you're accelerating lightly.
 
I can certainly notice when MDS kicks in (there’s a slight change in exhaust tone), but it seems to respond fast enough that I haven’t noticed any hesitation or anything I’d call negative.

If I’m cruising along with MDS active and I stomp on it the engine is back at full power before the transmission completes a downshift, so it’s not having any effect on acceleration.

The transition between modes takes 0.04 seconds, so if you can notice a delay there you may have a future career as an NHRA drag race timing system.
 
The other thing I will add is I think MDS only kicks in once the engine is up to full operating temperature. Also I deleted the muffler on my truck so it was really easy to hear the change in exhaust note, maybe that was some of the vibration I was experiencing.
About the MDS/ECO light, pretty sure everyone is talking about the ECO light, mine always kicked in whenever the ECO light turned on (I know they're technically not related).
 
jsalbre said:
I can certainly notice when MDS kicks in (there’s a slight change in exhaust tone), but it seems to respond fast enough that I haven’t noticed any hesitation or anything I’d call negative.

If I’m cruising along with MDS active and I stomp on it the engine is back at full power before the transmission completes a downshift, so it’s not having any effect on acceleration.

The transition between modes takes 0.04 seconds, so if you can notice a delay there you may have a future career as an NHRA drag race timing system.
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Nope, no career for me there. :) There are thousands of forum posts all over the various Hemi / Ram / Dodge forums from people with the 5.7L and the 6.4L who have noticed (and often are complaining) about the "throttle delay." It seems to be common across all vehicles with the Hemis, and not just the trucks.

My '15 was more noticeable in lag. My '18 is less. The mode is supposed to shift within 1 revolution of the engine, and at 1,500 rpm, that's 25 rps, or 0.04 seconds. But there's something about the engine that seems to lag bringing the hp up. Because the MDS actually causes the valves to stop opening, the engine is pulling in less air. Perhaps when the MDS kicks off, even though it's fast, the airflow takes a little longer to spool up? I don't really know, although I know that it's a detectable difference from doing exactly the same maneuver with the MDS disabled by selecting 8th gear.

Maybe it's reduced somehow in the '19s?

As I said previously, I don't really notice it normally, I don't tend to drive that hard and the system responds fine with my normal driving.
 
It’s possible that you’re feeling something there, though I’d put some money that a lot of the complaints boil down to “this is different and I don’t like it”. I bet if you took away any audible difference and didn’t tell anyone the feature was there then no one would notice.

It’s the same thing every time new technology comes around, especially on V8 vehicles, and doubly so on trucks. It hits the smaller stuff too though. People on the VW forums spend so much time figuring out ways to disable the start stop system, but there’s no point as the engine is back running before you can get your foot all the way off the brake pedal.
 
All I can say is try it for yourself. Get somewhere on flat ground at 55-60 mph, so you're relatively sure MDS is engaged. Try accelerating a few times at different levels but return to the same base speed. Then click your gear-downshift button once so your instrument panel says D 8. That just prevents MDS from engaging. Then try the same variety of accelerations and see what you think. If you can't feel the difference at all, oh well.

I think it's more detectable to folks with a heavy foot, honestly. And I don't tend to hear any difference. I am able to feel the vibration sometimes. It's really minor. It's never been an annoyance like a lot of these folks claim. Makes me wonder if something is actually not working right in their vehicles.

Yeah, folks complain about a lot of changes. Like all the complaints about losing the right hand column shifter for a dash knob in various forums. I don't get that, either. But.... it's their vehicle.
 
I‘ll give your test a shot when I get back home in a few days (yay work travel). I’ve never been accused of a light foot, so if heavy acceleration is what brings it about I should notice.

I can feel the vibration change and hear the tone shift, but that’s the only thing I’ve noticed so far.
 
After about 2000 miles on my truck I don't notice the MDS like I did at first...still trying to get used to the gear shift dial tho....old habits are how break I guess.
 
Distillusion said:
No. The ECO light is tied to a different circuit. When it kicks on, there is a good chance that the MDS is on, but it is not actually connected. At least not in the trucks I've had. BTW you can disable the light in the Uconnect menus, but that doesn't disable the MDS.
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Were all the trucks you drove HDs, or were some 1500s? I think the 1500 Eco light works differently. I can say with certainty that my old '15 2500 Eco light was 100% tied to MDS. Never had the light without MDS.
 
1HasBeen said:
Were all the trucks you drove HDs, or were some 1500s? I think the 1500 Eco light works differently. I can say with certainty that my old '15 2500 Eco light was 100% tied to MDS. Never had the light without MDS.
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Drove both LD and HD. Didn't notice a difference. Back when I got my first MDS, it was a 1500. I've seen a lot of discussions on forums over the last 5-6 years about this. Some swear the light is tied to MDS, some swear it's not. All I can say is that in my 1500 the light would go on even when MDS hadn't kicked on. I asked a tuner tech one time, and he told me the control for the light is based on whether the truck is running at reduced engine load, best fuel economy. MDS may or may not kick on, depending on what the computer thinks. I've had the ECO light kick on at times at speeds where MDS wouldn't. The tech said that if the truck is moving at a high enough speed and the throttle was low enough, the ECO light is triggered. The light would go on if MDS came on, but MDS wasn't required to kick the light on.

I've long since started de-activating the lights once I have the truck broken in.

(I have problems with the bad ergonomics of dash indicators that won't dim with the rest of the dash at night. ECO, Headlight, Foglight, Bright light, and others - none of them dim. So you're trying to preserve night vision with the dash dimmed down and those things are all at full intensity, seemingly a hundred times brighter than the rest of the dash, like the speedometer. Terrible design on RAM's part.)
 
Ahh. So that’s what that is. Just got my truck 6 days ago and have noticed a slight change in exhaust pitch and a slight vibration when I get settled in on a speed (especially driving around town at 25 30 mph). Then when I accelerate it snaps out of it and feels normal. Not that big of a deal but noticeable. I’m guessing won’t notice after a while.
 
I don't know yet if it's any different but I never ever noticed MDS in my 18 Jeep GC Hemi, hopefully the new Ram is just as smooth.
 
@JC said:
I don't know yet if it's any different but I never ever noticed MDS in my 18 Jeep GC Hemi, hopefully the new Ram is just as smooth.
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My RAMs have all been very smooth with it. It's pretty quick under normal driving, and with a heavy foot, it still doesn't kick, it just sort of spools up, quickly. Some guys complain about it. Not really sure why.
 
I wonder if RAM ever considered running the MDS only when the truck is idling. I find the "feature" annoying most times, but I don't mind it under about 20mph. Thought it strange that it clicks back to all cylinders when I come to a stop, though.
 
JDGreen said:
I wonder if RAM ever considered running the MDS only when the truck is idling. I find the "feature" annoying most times, but I don't mind it under about 20mph. Thought it strange that it clicks back to all cylinders when I come to a stop, though.
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Just be glad the 6.4 didn't get saddled with Start/Stop... yet
 
I have a new 6.4 and honestly I wish it had the auto start-stop. It's been on my last three vehicles and I'm so used to it that it really bothers me that this car stays running spending my money while I'm sitting at red lights. So from my perspective, hopefully the next full fifth generation of the heavy duties gets the start stop.

Sent from my SM-N960U using Tapatalk
 
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