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Discussion Starter · #1 ·
I have a 2007 Chrysler 300C with approximately 3500 miles. I have recently started to notice a slight surge / jerk sensation as the vehicle starts to barely accelerate while in fuel saver mode. I first started to notice it when driving on the highway with the cruise control on. On a level road everything is smooth but as the car goes up a slight grade and starts to advance the gas pedal to maintain speed, a small surge or kick is felt and the fuel saver indicator goes off almost immediately. The rpms don't change much but a slight needle width jump on the tachometer is seen (approximately 50 rpms at the most). The problem can be induced any time the car is in fuel saver mode and the gas pedal is barely advanced to just slightly accelerate. It does not appear to be downshifting as there is no significant rpm rise. It is not felt with a harder acceleration.

Has anyone experienced this same thing or have any ideas? I would think it should be able to be fixed as it never used to do it until lately. It definitely gets annoying after a while! I wonder if it could be fuel related?

Thanks
 

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It is not felt with a harder acceleration.
Well there ya go - - accelerate faster! Problem Solved! :pat:

Seriously though, I'm wondering if you are feeling the torque converter clutches unlocking as you slightly accelerate, rather than something directly related to MDS. I don't have an MDS indicator light (mine's an '05) and I cannot discern when MDS engages or disengages. I do know that the torque converter is a lock up design, but (as are many modern automatics) it's not an "on/off" thing like the older ones were. it's more of a gradual locking or unlocking (making it less obvious under most driving situations). But if you are cruising at a steady speed long enough for the converter to fully lock up, then when you accelerate slightly, the torque converter will begin to unlock gradually - - basically the clutches in the converter slip a little - - and you will see the RPM's rise slightly with no change in vehicle speed. If you accelerate more decisively, the the converter unlocks quicker and you don't notice the slippage because the vehicle speed rises along with the RPM's. Just a thought anyway.....
 

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I have a 2006 5.7 and if you are cruising at 50 on the freeway and hit a slight hill that causes the MDS to go back to 8 cylinder mode I can feel the car surge. I think it is more noticeable because the engine is accelerating and when it switches from 4 to 8 cylinders hit has much more power. Now going back the other way I can only tell a change in the exhaust drone.....I think this is totally normal......Oh, yes the tach doesn't budge and the transmission doesn't down shift.. so I don't think the torque converter ever unlocks
 

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I have a 2007 Chrysler 300C with approximately 3500 miles. I have recently started to notice a slight surge / jerk sensation as the vehicle starts to barely accelerate while in fuel saver mode. I first started to notice it when driving on the highway with the cruise control on. On a level road everything is smooth but as the car goes up a slight grade and starts to advance the gas pedal to maintain speed, a small surge or kick is felt and the fuel saver indicator goes off almost immediately. The rpms don't change much but a slight needle width jump on the tachometer is seen (approximately 50 rpms at the most). The problem can be induced any time the car is in fuel saver mode and the gas pedal is barely advanced to just slightly accelerate. It does not appear to be downshifting as there is no significant rpm rise. It is not felt with a harder acceleration.

Has anyone experienced this same thing or have any ideas? I would think it should be able to be fixed as it never used to do it until lately. It definitely gets annoying after a while! I wonder if it could be fuel related?

Thanks

Try pulling fuse 11 in the engine bay for 30 secs with the car OFF and then see if it does it on the highway. The car will eventually go into granny mode with the tranny becoming lazy and by pulliing fuse 11 its like a clean slate.
 

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I think the surging is the torque converter reacting to the change in 4 cylinder to 8 cylinder. So yes, the surge is indirectly the result of our car's having MDS.
Based on this article, the torque converter performance was designed to eliminate the 4 cylinder roughness.

Switching from eight cylinders to four decreases the frequency but increases the amplitude of engine vibrations. So the techies had to come up with a solution. They found it in the form of a torsional torque converter damper acting on the turbine side, in combination with a moderate amount of torque converter slip--but not so much slip that it negates the fuel economy benefits of running on just four cylinders. Together these two strategies absorb the V4’s harsher firing pulses, making the cylinder-deactivation transition seamless.
Building A 5.7-Liter Hemi V8 - Popular Mechanics
 

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Discussion Starter · #6 ·
Try pulling fuse 11 in the engine bay for 30 secs with the car OFF and then see if it does it on the highway. The car will eventually go into granny mode with the tranny becoming lazy and by pulliing fuse 11 its like a clean slate.



What does fuse 11 control?
 

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Joey, sounds reasonable to me...All I know for sure is that it is the MDS. To me it makes sense and the jerk is barely noticeable and you have to be in a narrow situation to even experience it. I don't see any reason to reset anything cause it will come back....
 

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What does fuse 11 control?
all i know is that it clears the comp and wakes up the tranny. The car has 3 different programs it can run which is decided on how you drive. So you pull the fuse and it re-learns how you drive giving you some great shifting for a while. if you have an 08 ITS NOT fuse 11
 

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I think I am having the same problem but it only surges while idling in (D) drive/automatic mode. I haven't had the problem at speed or while cruising speed. Can anyone shed some light on the subject for me please ?
 
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