MDS vibration

Skippy426 · Nov 11, 2015

Maybe I'm just more sensitive to it now but after my CAI and axle back, I can definitely feel and hear when it drops to 4 cylinders. It starts vibrating pretty good also... But if I use the ERS while it's doing it and put it into 5, the rpms don't change at all but everything smooths back out and quiets down. Now the road I'm on is pretty hilly and going up hill it seems that it's right on the verge of dropping back to 8 cylinders, but otherwise stays in 4. Accelerating is smooth, cruising with ERS in 5 is smooth (though it does seem like the torque converter doesn't want to lock up very quickly doing this). Anyone else notice or am I insane?

Oh... No idea when the plugs were changed last, or if they've ever been changed at all, if that matters... There's between 40k and 75k on them... Runs great though.

Chase300 · Nov 13, 2015

You are experiencing what is known as MDS Drone. Common discussion on LX forums.
Some aftermarket axle back exhaust systems are better than others at keeping the 4 cyl noise at bay...others not so much.

I believe Corsa was one of the first to promote their no drone axle back exhaust for MDS equipped Hemi's.
I'm sure there are other brands out there that also keep it at bay.
You might have to add a resonator.

Durangutan · Nov 13, 2015

As for the vibrating, my Ram's rear view mirror would visibly vibrate when it was in MDS. Irritating, Just enough to make the image a bit fuzzy.

Robfrmny21 · Nov 14, 2015

I know what you mean after my intake the drone is louder as well.

Skippy426 · Nov 14, 2015

Chase300 said:
You might have to add a resonator.

No.

Lol, it's only on hilly or windy areas that it's really noticeable... I'll just use the ERS or give it more gas to drop it out of MDS. Can't wait to get a tuner...

DDC · Nov 22, 2015

I have the same MDS vibration. 2011 HEMI Crew with Volant intake, HT Interceptor, stock exhaust and just changed the plugs to oem Police Package Mopar plugs about 3,000 miles ago.

personally, I think its an inherent quality in the MDS. and yes, it bugs me too. bugs me so much I'm beginning to consider just buying a Diablo tuner from HemiFever and having the MDS turned off.

on mine I noticed the vibration even when I bought the D last year when it was still bone stock. I'm not sure I would call what I feel drone. I would call it vibration in the driveline and steering wheel. I run around town in ERS 5 all the time which of course turns off the MDS. so when I'm cruising on the highway or interstate in D (Drive) I don't even need the ECO light to come on to know MDS has kicked in.

Skippy426 · Nov 22, 2015

2011CrewLuxSC said:
I have the same MDS vibration. 2011 HEMI Crew with Volant intake, HT Interceptor, stock exhaust and just changed the plugs to oem Police Package Mopar plugs about 3,000 miles ago.

personally, I think its an inherent quality in the MDS. and yes, it bugs me too. bugs me so much I'm beginning to consider just buying a Diablo tuner from HemiFever and having the MDS turned off.

on mine I noticed the vibration even when I bought the D last year when it was still bone stock. I'm not sure I would call what I feel drone. I would call it vibration in the driveline and steering wheel. I run around town in ERS 5 all the time which of course turns off the MDS. so when I'm cruising on the highway or interstate in D (Drive) I don't even need the ECO light to come on to know MDS has kicked in.

There is a Diablo tuner in the hopefully near future... But yes it's a vibration in the drivetrain. I've noticed that ERS 5 doesn't kick into final overdrive unless EVERYTHING is warmed up, whereas D seems to drop into MDS and final overdrive as soon as the coolant is around 170.

Side note- where did you get those plugs, what's the part number, and how well do they work because I've read that the 5.7 is very picky about plugs.

DDC · Nov 22, 2015

ERS should be using the lower 5 gears (in 2011's). it should be enabling the 2*(Prime) gear and locking out the top over drive gear which is 5 in normal operation. normal 4th & 5th gears are both overdrives and very close in ratio. ERS should be operating very similar to Tow/Haul by changing shift mapping and holding gears longer. to me, ERS 5 makes so much more sense for around time driving. as a bonus it disables MDS, just like Tow/Haul.

the plugs are the oem Mopar plugs developed for the Police Package HEMI's. they're made of Iridium instead of copper and they're rated for 100k miles. (link below). they're pricey, lowest I found was about $160 for the set of 16. dealer cost is close to $13 per plug. I bought mine from the local Dodge dealer. I had a $150 certificate from FCA for getting recall work done or I would have purchased online. changed the plugs myself and since I probably drive only about 12k miles a year, hopefully will not have to change plugs for a good long time.

part #SP143877AA

Jeep Grand Cherokee Spark Plugs (Part No: SP143877AA x 16)

my HEMI loves the plugs. these are genuine Mopar plugs developed for the HEMI. just pricey so reserved for the Police Package vehicles.

Skippy426 · Nov 22, 2015

2011CrewLuxSC said:
ERS should be using the lower 5 gears (in 2011's). it should be enabling the 2*(Prime) gear and locking out the top over drive gear which is 5 in normal operation. normal 4th & 5th gears are both overdrives and very close in ratio. ERS should be operating very similar to Tow/Haul by changing shift mapping and holding gears longer. to me, ERS 5 makes so much more sense for around time driving. as a bonus it disables MDS, just like Tow/Haul.

the plugs are the oem Mopar plugs developed for the Police Package HEMI's. they're made of Iridium instead of copper and they're rated for 100k miles. (link below). they're pricey, lowest I found was about $160 for the set of 16. dealer cost is close to $13 per plug. I bought mine from the local Dodge dealer. I had a $150 certificate from FCA for getting recall work done or I would have purchased online. changed the plugs myself and since I probably drive only about 12k miles a year, hopefully will not have to change plugs for a good long time.

part #SP143877AA

Jeep Grand Cherokee Spark Plugs (Part No: SP143877AA x 16)

my HEMI loves the plugs. these are genuine Mopar plugs developed for the HEMI. just pricey so reserved for the Police Package vehicles.

Thanks for the plugs! I'm thinking come spring mine are gonna be due.

As for ERS, I've noticed that if I'm in D and put it too 5 before the trans and oil and all that is fully warmed up it'll drop down a gear. But if I wait till it's fully warmed up it'll stay in top overdrive but disable MDS, and it'll still shift normally through all the gears and back to top overdrive

DDC · Nov 23, 2015

hmm... here's what the Owners Manual says about ERS.

5.7L Engine
On vehicles equipped with the 5.7L engine, use of ERS (or TOW/HAUL mode) also enables an additional under- drive gear which is not normally used during through- gear accelerations. This additional gear improves vehicle performance and cooling capability when towing a trailer on certain grades. ERS 1, 2, and 3 are underdrive gears; ERS 4 is direct drive. ERS 5 (Overdrive) is the same as the normal 4th gear. When in the DRIVE position in first through fourth gear, the first tap to the left (-) will display the ERS designation for the current gear (the transmission will not downshift). For example, if you are in DRIVE and are in third (direct) gear, when you tap the shift lever one time to the left (-), the display will show 4 (ERS 4 is direct gear). Another tap to the left (-) will shift the transmission down to ERS 3 (the added underdrive gear). When in the DRIVE position in fifth gear, the first tap to the left (-) will downshift the transmission and display 5 (ERS 5 is the same as normal fourth gear). Another tap to the left (-) will shift the transmission down to ERS 4 (direct gear).

normal 4th and 5th gears are really close. I suspect you just haven't noticed the slight difference between the two. this is what makes ERS so great around town, you still get an overdrive gear.

according to Allpar, the 5speed 545RFE and 6speed 65RFE are essentially the same transmission.

"The next six speed derived from the 545RFE was the 65RFE, used with V8 versions of the Ram 1500, Durango, and Grand Cherokee. The 65RFE only has six forward gears in ERS/AutoStick mode or kickdown mode; it is essentially a software and name change..."

MDS vibration

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Chase300

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DDC

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DDC

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