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hello all, I am new to the forums. I just recently purchased a dream car of mine, a 2015 RT dodge challenger. I have been in love with the car since seeing the movie vanishing point as a little boy, so I'm very pleased with my purchase. However, I do have a small issue. I have never driven a A8 automatic transmission I don't know if this is normal or not or what's really causing this issue. but when I am holding speed in any gear, I stay around 55 or 60 most of the time, the car feels like there is a shutter. But when I step on the gas it goes away, however when I go back to holding the pedal to keep it at one speed it starts back and like I said this does it at any speed when holding it. So I am wondering if anyone here has has the same issue and what was causing it. It is not noticeable in sports mode but it is in regular driving mode. Sorry for the long post and thanks for any advice!
 

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The Bacon Hauler (‘12 Cop Charger)
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Sounds like that is the MDS kicking in at cruising RPM and kicking off when throttle applied.

Nothing to worry about, it’s expected, even if not desired, behavior for the auto trans v8 cars
 
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The Bacon Hauler (‘12 Cop Charger)
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So this is normal and nothing to worry about? The it never does it in sport mode so thats what's been throwing me off a little thanks for the quick response.
It is disabled when in sport mode and also when trans is in AutoStick mode

All it is is the engine running on 4 cylinders instead of all 8 in an effort to increase MPGs. Unofficially that’s when it becomes a Semi-Hemi 🤣
 

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All it is is the engine running on 4 cylinders instead of all 8 in an effort to increase MPGs. Unofficially that’s when it becomes a Semi-Hemi 🤣
😂😂 Thanks for letting me know the last few days I've been scratching my head over it because otherwise the car is damn flawless ...Don't know why Dodge thinks we care that much about mph otherwise we'd buy a Honda.
 

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The Bacon Hauler (‘12 Cop Charger)
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😂😂 Thanks for letting me know the last few days I've been scratching my head over it because otherwise the car is damn flawless ...Don't know why dodge thinks we care that much about mph otherwise we'd buy a Honda.
They know it is not a selling point, they’d just as soon not have to mess with it on the engines either I imagine. They actually do it to satisfy CAFE requirements set for all auto makers years in advance. If they don’t meet the MPG numbers set by some previous administration, they could lose out on incentives or be outright fined.

If you think the MDS operation is unpleasant now, replace the stock exhaust with something more throaty. Aftermarket exhaust hates the 4 cylinder mode, and they will sound like crap while it’s operating in it with them.
 
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They know it is not a selling point, they’d just as soon not have to mess with it on the engines either I imagine. They actually do it to satisfy CAFE requirements set for all auto makers years in advance. If they don’t meet the MPG numbers set by some previous administration, they could lose out on incentives or be outright fined.

If you think the MDS operation is unpleasant now, replace the stock exhaust with something more throaty. Aftermarket exhaust hates the 4 cylinder mode, and they will sound like crap while it’s operating in it with them.
I couldn't agree more. I replaced the stock exhaust with magnaflows. The drone when MDS is on will drive a person insane. I'm in sport mode 90% of the time.

hello all, I am new to the forums. I just recently purchased a dream car of mine, a 2015 RT dodge challenger. I have been in love with the car since seeing the movie vanishing point as a little boy, so I'm very pleased with my purchase. However, I do have a small issue. I have never driven a A8 automatic transmission I don't know if this is normal or not or what's really causing this issue. but when I am holding speed in any gear, I stay around 55 or 60 most of the time, the car feels like there is a shutter. But when I step on the gas it goes away, however when I go back to holding the pedal to keep it at one speed it starts back and like I said this does it at any speed when holding it. So I am wondering if anyone here has has the same issue and what was causing it. It is not noticeable in sports mode but it is in regular driving mode. Sorry for the long post and thanks for any advice!
Congrats. I have a 16 RT. My first new car in 20 years. Love it.. You'll also experience transmission lunges when engine is cold, and the occasional hard downshift. Normal for the transmission, nothing to be concerned about. Performs like a champ on WOT.
 

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😂😂 Thanks for letting me know the last few days I've been scratching my head over it because otherwise the car is damn flawless ...Don't know why dodge thinks we care that much about mph otherwise we'd buy a Honda.
The automatics have MDS and the manuals have the skip shift so that they can meet the advertised MPG ratings
 

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Double check your assumptions by setting your instrument cluster gauges to the "fuel mileage" setting. When the MDS comes on, there will be the green "4CYL" light on the cluster (your drone and trans will sound different at that point) and if you "blip" the gas, the 8 cylinders will come back on line and the trans and drone will get different again--- all normal.
 

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2015 RT Shaker (STP/A8/FORGED/NAPPA/NO SUNROOF)
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Normal for regular mode.
 

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Discussion Starter · #11 ·
Double check your assumptions by setting your instrument cluster gauges to the "fuel mileage" setting. When the MDS comes on, there will be the green "4CYL" light on the cluster (your drone and trans will sound different at that point) and if you "blip" the gas, the 8 cylinders will come back on line and the trans and drone will get different again--- all normal.
Yeah I did that little test and when the car does the little shake (mainly you feel it in the gas pedal) its dropping down to "4" I've just put it in sport mode and left it alone...Because I'm changing the exhaust and I've heard when it drops to "4" it sounds like pure crap.
 

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hello all, I am new to the forums. I just recently purchased a dream car of mine, a 2015 RT dodge challenger. I have been in love with the car since seeing the movie vanishing point as a little boy, so I'm very pleased with my purchase. However, I do have a small issue. I have never driven a A8 automatic transmission I don't know if this is normal or not or what's really causing this issue. but when I am holding speed in any gear, I stay around 55 or 60 most of the time, the car feels like there is a shutter. But when I step on the gas it goes away, however when I go back to holding the pedal to keep it at one speed it starts back and like I said this does it at any speed when holding it. So I am wondering if anyone here has has the same issue and what was causing it. It is not noticeable in sports mode but it is in regular driving mode. Sorry for the long post and thanks for any advice!
Does your car have cruise control? If it does do you still get the same shudder if you put it in cruise control?
 

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I don't notice it as much in cruise control
But you do notice the shudder while using cruise control right? If so, this could be related to any of the following: failing coil on one of the cylinders, worn transmission engine mounts, a U-joint that is starting to fail or it could be more serious such as a short stroked cylinder or faulty ECM module. If it were me, I would try and knock out the simple things like failing cylinder coil's or an ECM issue by either using an OBII or OBIII diag tool to see what it tells me. However, if you're not comfortable with working on your own car, then I would take it to a reliable dealer or mechanic and have them run the diagonal tests on your engine. A standard compression test will reveal whether or not you have a short stroked cylinder. As for the U-joints you will need to put it up on a lift and inspect them for wear and play. Again if you're not comfortable doing this type of work yourself I would take it to a reliable mechanic or dealer. In closing, I hope this helps give you some ideas as to where to start diagnosing the issue.
 

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2008 Challenger SRT8 #1101. 2005 Dodge Magnum RT AWD
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hello all, I am new to the forums. I just recently purchased a dream car of mine, a 2015 RT dodge challenger. I have been in love with the car since seeing the movie vanishing point as a little boy, so I'm very pleased with my purchase. However, I do have a small issue. I have never driven a A8 automatic transmission I don't know if this is normal or not or what's really causing this issue. but when I am holding speed in any gear, I stay around 55 or 60 most of the time, the car feels like there is a shutter. But when I step on the gas it goes away, however when I go back to holding the pedal to keep it at one speed it starts back and like I said this does it at any speed when holding it. So I am wondering if anyone here has has the same issue and what was causing it. It is not noticeable in sports mode but it is in regular driving mode. Sorry for the long post and thanks for any advice!
my SRT8 was doing something similar to that but it does not have different modes as it was the first year it was made and those were not part of it yet. I found out that mine was actually caused by the wheels which had been enlarged to 22 inch rims by the previous owner. I don't know if they were slightly warped or not counterbalanced correctly or if it was just because the tire was that low profile but any shuttering issues I had which I felt through the steering wheel sometimes went completely away when I changed my wheels.
 

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But you do notice the shudder while using cruise control right?
I can feel the car change from 4 to 8, or 8 to 4 cylinder mode - I would describe the effect as more of a drone in the exhaust system in lower RPM's - rear view mirror will vibrate - has done it since the car was new, never really considered it a mechanical issue....I knew very little about these engines.
 

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I can feel the car change from 4 to 8, or 8 to 4 cylinder mode - I would describe the effect as more of a drone in the exhaust system in lower RPM's - rear view mirror will vibrate - has done it since the car was new, never really considered it a mechanical issue....I knew very little about these engines.
It could also be the muffler mounts have worn out.
 
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