Well, I see lots of MDS issues and tranny issues so I figured I'd slap them together. I have an 06 Hemi QC 4x4 w/73,000 miles. Bought the truck in 09 w/46,000 and unfortunately just had to have the trans rebuilt. First, I wanna ask how the trans is SUPPOSED to react to MDS kicking on and off. Seems to me when I bought the truck, at cruising speed when the MDS would kick on/in the RPMs would slightly increase. When it went back to 8 cyl the RPMs would drop a little. Is this correct and if so how does the trans compensate for this?

Here's my issue (I think). After the trans was rebuilt (couple weeks ago) I have noticed that the MDS wouldn't kick in at all after a 30 mile trip. After driving it one or two more times it started to kick in but it still takes forever. It used to kick in withing 5-8 miles or so. now I'm driving probably 15 or more till it kicks in. Today i drove almost 30 before it kicked in at all. I have only driven it 5-7 times since the rebuild though so I'm wondering if the TCM/PCM is still adjusting itself?

Also, when the MDS kicks in now, the RPMs stay pretty much the same. That seems to cause it to engage and disengage more often than before. Also, I can get up to around 37 mph and get the trans to drop into overdrive and sit around 1,100ish RPM. Sometimes the MDS kicks in too. Before the rebuild it never caused an issue but now when MDS kicks in it feels like the truck is lugging. Like it's in a (numerically) higher gear than it should for the vehicle speed/engine speed. Any ideas? I know I need to talk to my rebuild guy but I wanted to get some other opinions before I spoke to him.

Sorry for the long post. I just wanted to try to be as specific as possible.

Thanks

 

It is normal to gain about 300rpm in MDS. From what I have read, it partially unlocks the torque converter when in MDS mode.
Sounds like yours may be relearning the new transmission. You might want to unhook the battery for about an hour and start over on the relearn. It shouldn't take too long.

 

I asked the same questions about a month ago. I bought my truck in Jan and it is the exact same truck as yours , color and everything (nice choice) with 54K on it. within a month of getting it the LR shift solenoid went out and i had to have it replaced. the transmission guy said that there was a lot of torque converter material in my pan when he dropped it and said it may be going too.

My MDS was kicking in and out exactly like yours was and i hated it. the RPMs going up and down and it never settled in MDS and was constantly shifting. so i just turned it off with my Diablo. i have found that the gas mileage is really no different. after 3 tanks i am getting the same mileage out of a tank of gas. and no annoying shifting and worries about the tranny.

I fear that the constant shift in and out of MDS was causing unnecessary wear and tear on the converter. like stated above, when the converter comes out of lockup and goes back in a hundred times a 20mile trip to work cant be good on the internals.

how did you know your tranny was going bad? any tell tale signs? i am concerned about mine as well. how much did it cost to get it rebuilt? thanks for the info.

 

Thanks. I suppose it couldn't hurt to try to reset the PCM before I contact my tranny guy again. I thought it was normal for the RPMs to change. Problem is mine don't change anymore since the rebuild. I'll try the reset and see if that helps.

When the trans started acting up it was acting like it didn't know what gear it wanted to be in. When it shifted from 1st to 2nd it felt like it "let go" for a split second. Then the check engine light would come on and off intermittently till finally the trans went into 'limp' mode where it's stuck in like 3rd gear. The weird thing was that after that it drove normal and then started acting up again.

I got a couple quotes for it and ended up paying $1600 for the rebuild.

 

do all new rams with the hemi have mds? i bought mine used its a 2008 with 19,000 miles on it six months ago. the dealer ship couldnt tell me anything about the truck other than were to put they key.

 

IIRC its on all hemi's 2006 and up. Not sure if they're still doing it on the 09+ trucks?

 

Sorry I've been off this site for a long time. You probably already found your answer but yea, 2006 and up have MDS on the hemi.

Also figured I'd update. (Just bought a 2010 Ram and would like to become active on the forum again). As far as the trans issues with my 2006 it seemed to be the shop's fault. I took the truck back and they rebuilt my trans again. Still had problems. Took it back and they rebuilt another core and put that in. Still had problems. Finally they said they ordered a new trans from Chrysler and put that in. Had a minor issue with that but overall the trans seemed ok.

I had several other issues with that truck that caused me to sell it last friday. I picked up a 2010 Mango Tango Ram with 28,xxx miles. Hate to say it (after all chrysler vehicles) but this will be my last Ram if I have as many issues with it as I did with my 2006. Hopefully I have as many issues with this as I did my 98 Ram (none other than maintenance).