I have the factory duals and I can hear and feel the MDS kick in. There is a distinct sound that's for sure. I know the rumble you are talking about. I sometimes defeat the MDS by pushing the tow/hual button, that locks out the MDS system, it does a few other things as well that kills MPG's. There are times when I want the truck to sound like the killer Hemi that it is not like a 4 banger! Build date July 09.

 

I have a Larmie crew cab,hemi.built after the bankruptcy.When the MDS kicks in at low speeds there is a strong rumble and it allmost feels like it is lugging.I recently removed the resonators (rear dual exhaust,single stock muffler)looking for a little better sound.Sounds a little better except when the MDS cuts in at low speeds.The growl,lugging thing is more pronounced,first time my wife noticed.Not sure what a magnaflow will do?

 

This sound is getting worse. I have 2600 miles now and right at 1400 rpm, while in MDS mode the truck sounds awful. Like there is not a muffler at all. Like you are towing something right up against the exhaust and getting the vibration and sound. Just hoping that some exhaust change will help this. It is stock single now. Just hate going down the road and all of a sudden the loud roar and lugging starts. I love this truck but that is not normal for it to vibrate and get that loud.

 

We are the only ones that are normal everyone else it nuts LOL. I don't hear a thing, I have a prior to Dec 09 so mine has no light I try everything to try to hear or engage mds like keep the pedal steady or put the cruise on at a low speed, my truck must has super insulation I can't hear nothing, maybe cuz of the bed rug in the back might muffle the exhaust. This truck is as quiet as some luxury cars I have been in.

 

I have a pre-dec 09 big horn Hemi with 3.92 gears that makes the same rumbling noise...sounds to me like a worn AC compresssor running. It's been to the dealer twice ... second time the tech finally heard it and says it is a resonance problem. He's been on the chrysler tech line trying to find a solution but nothing back yet.

 

Mine makes the same sound (build July 09) and seems to be getting louder IMO. When I first bought the truck, other than the fuel saver I couldn't tell when MDS kicked on. Now with 4100 miles on it, at low speeds especially when the engine is cold or if it kicks on while accelorating up a hill it is very pronounced.

 

I also have a pre Dec09 Ram hemi, single exhausts, with no fuel saver light. I have tried to hear a change in exhaust tone when mds kicks in, but I don't notice a difference. Best I can do is monitor the avg mpg. But that is not really telling when mds kicks in and out.

 

Mine also does this (09) but never in MDS mode. If I am going over 50 mph and get in the 1300-1600 rpm range I hear what sounds like a metallic vibration. It was always under a slight load such as going uphill and barely on the throttle, even more noticable while pulling my boat. It now does it more often and even on straightaways. Just barely touch the gas and it is gone. Local tech could not reproduce the problem. I will have to take him for a ride the next time. I really don't think it is an MDS problem since I have read about it happening in and out of the mode on another 4th Gen Ram forum. I have payed a lot of attention to it and it is only in this rpm range. Mine is an 09 Ram 4x4 Hemi with factory duals

 

I have it right at 1500 rpm. Sounds like a metallic rattle, maybe like a heat shield vibration. Anyways I fixed mine myself after going to the dealer 3 times. I have a Nov. Build Crew Cab Sport Hemi with the 3.55 rear axle. It was making the noise at 1500rpm under light acceleration. With MDS on or off.

I noticed the rubber hanger for the exhaust pipe located under the front passenger seat was slid rearward to the end of its pegs. There are 2 rubber hangers along the passenger side that hold the exhaust pipe close to the frame, one under the front passenger seat and one about where the cab and bed meet. My front rubber isolator was sliding back and allowing a vibration. I used a zip tie at first to hold the rubber hanger to the front of the pegs (farthest towards the engine). I drove it for several days and no sound. Took the zip tie off and the sound was back. The deal put 2 rubber hangers on and its fixed.

Also, for those early build with no MDS light. My dash cluster was flickering occasionally and they replaced it, now I have the light. So cool.

 

Just got back from the dealer. I told them of my (our) problem and they said there is a flash to fix mds drivablility issues. So far after the flash, it is MUCH better.