matt3, can you watch your fuel mileage and let us know if it changed after the MDS Update. My dealer said there was a MDS flash, but didn't suggest it to me as I am getting 20-21 mgp on the highway. He stated he saw some drop to 16-17 post flash, wondering if they are 3.92's or 4x4 or driver influenced drops.

 

I'll keep an eye on it.

I don't really care though, I was originally asking the dealer to turn the MDS off. They denied they could but, I told them a simple aftermarket programmer could do it and that I doubt that a dealer would lack the ability. Then they suggested this flash. So far so good.

 

[quote=skyhawk763;1949077]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.

quote]

EXACT same issue here, EXACT same fix, too! (well, I used tie wire instead of a zip-tie!)

I have a 09 Reg cab Shortbed. SLT ,5.7 w3.92. At 38 MPH, in 'fuel saver' mode, with a slight load on the engine, it rattled like 'an adult novelty' set on "HI" placed up under the bed of the truck!!! ANNOYING as 'you know what'!!!!

Made this noise since 'day one'. Made it during my initial 'test drive' before purchase. (Thought a nerf bar was making the noise, as one was loose) Truck had 238 miles on it. That was the end of December 09.

Noise seems to originate from the 'middle' of the truck (left and right), and seems to come from the 'front' of the bed / rear of the cab area. (kinda hard to 'pinpoint' by ear)

On a Reg cab, there are (2) exhaust hangers about 8 inches apart at the cab/bed junction. Both are individually offset from the centerline of the exhaust pipe. (1 slightly left, 1 slightly right) The Hemi will 'shake' a little bit at just the right RPM and load when running on 4.

What was happening in my case was that, with the 2 hangers being slighly offset from each other, the exhaust pipe would shake back and forth enough that it 'slapped' the rubber bushings back and forth,,, At one moment, a rubber bushing would be being 'pulled', (in expansion) and the next moment, it would be being 'pushed' (in contraction) The rapid 'back and forth' slapping of the bushing(s) from 'push' to 'pull', basically 'hammered' against the steel hanger, which is welded to the hollow box frame.

Just like beating on a drum,,,,

At first, I removed the front rubber bushing and went for a test ride. An instant 95% improvement!!!

My front rubber bushing was also slid all the way 'back'. The hanger rod was 'polished' in the area where rubber was slappin aroung on the hanger.

In order to 'tighten up' the 'slack' between the 2 rubber bushing's (front and rear), I slightly bent the rear frame mounted hanger 'outward',,, I re-installed the forward rubber bushing, and slid it all the way forward. Secured it with tie wire.

At this point, you REALLY have to be listening for it to even realize there is any rattle at all.


I hate rattles.

I hate trying to describe rattles to the Dealer.

I hate taking 'Service Representatives' for rides to have them listen to and acknowledge there is a rattle, only to have them later say they couldn't make it rattle when the Tech was riding with them,,,,

Hopefully this will help someone else,,,