MDS Shutter and shake first and second

[GarrettLaube]

Hello everyone!!

I am back again with more testing since my last post. To recap, I drive a 2014 1500 with the 5.7 and zf 8hp70 , I run a 93 octane tune but drive mostly with my MDS on(not full time active). About 4 months ago shortly after I had acquired the tune I noticed a slip or shake when shifting between first and second making a right hand turn out of my subdivision. Since my OP I have done some ¨real world¨ testing but no dedicated day to testing, just play with the throttle some as Im driving to and from work. Here is what I have observed.

I know the ram does have the eco light but I also know that just because the eco light is on doesn't mean that the MDS is active. I prefer to keep the MDS on for that little itty bit of extra fuel I save but I believe I have pinpointed my shifting shake issue. Since the MDS system actuates under load I have done multiple trial runs with light throttle and MDS on and off. The usual test consists of me turning the MDS off through the diablosport (or the TH mode just because) and rounding the right hand turn out of my subdivision.

In the trials with my MDS off or in TH mode and not even quarter throttle the shift is rumbly but no where near as bad as before. Turn around and repeat the process with MDS on and I get the rattle and shake that I am much use to as soon as I hit 10 mph or 1500 rpm as the transmission shifts. I want to reiterate that the shake ONLY OCCURS DURING OR SHORTLY AFTER THE SHIFT, I can get it to shutter longer by playing with the throttle attempting to actuate and then deactivate the MDS shortly after shifting to second. None of this occurs if I either A)keep MDS on and just power through my turn keeping MDS deactivated by keeping the load on the pedal high, or B)Turn MDS off or put in TH mode and just quarter throttle through the turn, just enough load to actuate the MDS but ofc it cant because I have told the engine not to.

Does anyone at all have any insight or explanation on the engineering of how the MDS affects the transmission or if it even does?? Looking for an explanation more then a fix as I can live with it by keeping MDS off or just ignoring it.
Thanks for taking the time to read this.

 

[jws123]

How many miles are on it? you may have a underlying trans issue that is worse when mds turns on have you checked your trans fluid level ect?. Most of us disable mds for a lot of reasons 1 it really saves little to no gas 2 it causes more issues then good 3 It makes the truck feel and sound like a prius its a flawed design my opinion nothing good comes from keeping it on.

 

[GarrettLaube]

It is sitting at just over 95k. I have checked my trans fluid and even had it flushed back in november, the dealers fix for this problem which did not work and just left my wallet lighter. You are right the MDS does not save that much fuel and seizure of a component that is meant to be in constant rotation overtime does cause issues. Running 93 is not cheap so any fuel I can save whether be in theory or application I will gladly take, I do see your angle of the mater however. Just another flaw to add to the list caused by EPA regulations.

 

[Wild one]

It is sitting at just over 95k. I have checked my trans fluid and even had it flushed back in november, the dealers fix for this problem which did not work and just left my wallet lighter. You are right the MDS does not save that much fuel and seizure of a component that is meant to be in constant rotation overtime does cause issues. Running 93 is not cheap so any fuel I can save whether be in theory or application I will gladly take, I do see your angle of the mater however. Just another flaw to add to the list caused by EPA regulations.

You're running a 93 tune,and worried about milege,do you live on planet earth,lol. Learn to manually shift the tranny till you're above 50 mph or at least shift it down so that 8th is showing on the Evic,then kick it up at 50 mph so the mds becomes active again,as the mds won't give you any better milege under 50 mph.BTW who in hell is tuning your truck for 93 octane and still leaving the mds engaged,i'd be almost looking at your tuner and his tranny tuning abilities
If you're running just a canned 93 tune,you're nuts,no matter how many bolt-ons you have,your truck will at very most need a 91 tune

 

[PoMansRam]

You are going to feel a rumble or vibration from the MDS on pretty much every Ram 1500 equipped with it during certain driving situations. No way to mitigate this completely when a V8 is forced to run on 4 cylinders.

Like wild one said, all you have to do is put it in 8th with one button push and MDS goes away until the next time you spin the shift knob or cycle the ignition.

I pretty much always disable MDS if I'm tooling around at speeds less than 55mph or in stop/go conditions because the NVH associated with it drives me nuts. Your average owner doesn't even know it's there. I've talked to many late model Ram 1500 owners who either have no clue about MDS and have no idea you can temporarily disable it.

 

[NJMOPAR]

FYI, tow/haul does not disable MDS, it changes the shift points. Short of using a tuner, only way is to use the +/- button to manually select a gear.

 

[caulk04]

I'm very suspect that MDS is operating in 1st or even 2nd gear. 20mph or close to it should be the activation speed. My last MDS Hemi was 20mph on, ~17 it would shut off. It may be lower in these.

Try it as NJ suggest, use the +- button to display 8 in the dash and see if it still behaves as you're described. Not discounting what you're feeling, I just don't think it's strictly and MDS related issue.