New dodge owner and new to thesite, need help.I purchased a new 2007 Ram Hemi QCMDSand installed a new exhaust...si/do magnaflow..no other mods to date. My question is this...ever since the exhaust was installed, the shift points have been eratic..ie..during acceleration the shifts are fine...its when im cruising along at 30-40 that it wants to shift into od to soon causing it to bog down and fall on its face...it also seems to engage into 4 cylinder mode too soon 5-10 mph it will engage. My dealer told me the new exhaust iscausinga reduction in back flow..which is causing the transmission to misread from the computer. Does the sound to be true..or is the stealership screwing with me? Any help would be appreciated.

 

I installed Magnaflow 16699 on my 07' hemi. I noticed the eratic shifting. Never took it in but I'm looking for others with the same problems first.
Dealerships have a way with putting problems on aftermarket parts even if they are not the problem.

Did you ever confirm if the exhaust was the cause?

 

sounds wierd, did you reset the computer by disconnecting the battery? will have it relearn the shifting habits and such, this time with the new exhaust system

 

I just finished mine today, 16701, and no issues. Are you sure you arent interpreting the MDS it self as the weird shifting? I have noticed with the Magnaflow muffler you can notice the MDS 20000000000% more. It causes a low rumble in the cab and I can see how that would be viewed as erratic shifting. Drive around in O/D off mode and see if you still have the issue - if it is a backpressure issue it will still shift funny, but if it is the MDS engaging causing you to think it is shifting then this will stop as MDS is off in OD off mode.

First this I thought when it went into MDS was that the tranny shifted. All in all I am still on the fence with MDS – when it is active I can get around 20MPG, when it is inactive I am around 17 or so (highway at 66 MPH, 1,300 miles on truck)

JD

 

I left the battery unhooked for about 1 hour. The funny thing is that today the temp dropped about 20 degrees and this made it even worse.

 

I drive 40 miles to work with cruise control on 70mph. I can watch the rpm's go from approx 1950 to 2200. Up/down. No hills. No wind.

 

I don't know if this will help but...

Taken from KenHemi on Dodge Talk

Disconnecting the batter will not reset the pcm.

You need to leave the battery connected, remove the pcm fuse then buckle the driver seat belt, put the key in and turn to start and hold it there (it won't start). You will hear a chime and if you hold it a lttle longer you'll hear a 2nd chime.

The first chime is the pcm is reset. The second is the trans control is reset.

Disconnecting the battery will reset some stuff, but not the pcm stuff that you are looking for.

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Remember to put the fuse back in
What kind of Gas are you guys using?

 

Using 87 octane. Drove to work this morning at 75 mph and worked fine. Rpm at2200. No erratic shifts. Had to slow down to 65 for slow traffic and RPM came down then came up to about 2300 and stayed there. Had to pedal it to get transmission to shift.

 

Thanks guys...I will try to reset the pcm and see if that works.

 

I have made some calls to another dealership and they stated the pcm may need to be reflashed for the new exhaust. I called around to various exhaust shops and they told me theyhave changed alot of these trucksexhaust and have never heard of any proplems to date.Toanswer the question about the mds kicking in....I too can hear themds kick in...but the problem im having is its kicking in at 5mphlike when driving through a parkinglot andim just easing through it will engage...secondlyI can hear the engine change swiftly into od if off theaccelerator say cruising at speeds of 30 to 40 mph. I have read where the factory exhaust masked these transmission behavior where you couldn't hear all the actions of the transmission. With an after market exhaustyou can hear and feelall the little actions of the transmission in more detail. Im not sure...this is my first Dodge and Im trying to get to know how these things work.