I have a brand new '09! 5.7 Hemi! When my truck goes into the 4cyl mode and I hold the throttle right at 1300 to 1500 RPM, the exhaust or something lets out a big roar and vibration. Speed up and it goes away, let off and go under that 1300-1500 range completely stops. Just wondering if a new exhaust would help. I hate for a new vehicle to have such a problem. Have taken it to dealer and no solution. 1200 miles on the truck. Other than that problem it has been an Awesome ride!!!! Any help would be great!! Ram Tough

 

check out http://www.mufflex-performance.com/
thats a popular system around here....

 

It will most likely not help. Would like a vid to hear it, but right now I would recommend a programmer and turn off mds

 

I just ran to the store and right about 1400rpm and 40mph it let out a big roar! As long as I held it right there it continued. I dont think it is only during mds because I can be coming up through the gears and if I hold it right in that range before transmission shifts it will do it! If you hold the throttle just right it will really roar!!

 

I would keep taking it back to the dealer. What was their explanation?..."its normal"

 

Yeah, definately make a video or audio recording of it happening. Sounds more like the hill assist than the mds to me though. Is it while you're driving up a hill?

 

nope. When I hit that magic rpm range and am barley in the throttle it roars.

 

Mine makes more noise when the MDS is in 4 cyl mode, and it is louder at lower RPMs. Without hearing it I couldn't say for sure, but it sounds normal.

Putting a mufflex or other less restrictive exhaust on the truck is only going to make it louder. As for turning the MDS off - bah. It was one of the reasons I bought the truck.

 

i just purchased 2010 and i have the same thing going on. i took it back to the dealer and had the service manager ride along with me so he knew exactly what it was/what i was feeling. he claimed it was something to do with the mds and its not a problem. i had him put it in the computer that i was in for that to be checked out at 700 miles old and that should something happen that it be fixed correctly. so i will keep you informed should anything occur

 

could this be a trans issue? almost as if its downshifting ?