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I noticed this problem when I first drove my 2009 LTZ (6 speed) but it seems to be getting worse. If I'm cruising down the highway at 65 and take my foot off the accelerator (such as when coasting downhill) the transmission *really* pulls on the engine and then I get a "shudder" as if I tapped the brakes slightly -- enough to make my head move forward/back. I've been experimenting with this and it's driving me crazy. With my Grand Prix, when I would take my foot off the gas, it coasted like a son of a gun; my Boo doesn't seem to want to coast at all -- when I take my foot off the gas it feels like I hit a gust of wind coming at me -- the slow down is very noticeable. Has anyone else experienced this? It seems to be at its worst in 6th gear, but I notice it in 5th as well (I would expect this if I had manually in 5th gear and revved up and I took my foot off the gas, but not at 30mph on the level).
 

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Noticed this on mine also (09 2LT V6). What I "think" it is doing is downshifting, infact if I put it into manual mode I can see it downshifting.

Guess it is a "feature" of the 6 sp tranny:)

But as I taking it to the dealer tomorrow to do the BT upgrade, and take care of the tranny recal will mention this to see what they say.
 

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Noticed this on mine also (09 2LT V6). What I "think" it is doing is downshifting, infact if I put it into manual mode I can see it downshifting.

Guess it is a "feature" of the 6 sp tranny:)

But as I taking it to the dealer tomorrow to do the BT upgrade, and take care of the tranny recal will mention this to see what they say.

Mine was downshifting at first -- did like you did, checked and sure enough it showed M5 -- so they had to reprogram how it shifts. Now, it's almost like it's trying to downshift, but doesn't (when I put it into manual, it shows M6 but sure feels like it was trying to downshift at 65mpg).

I hope it's not a "feature" of the 6sp tranny -- I hate that loss of momentum feeling!
 

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On mine, I feel the shudder and then I believe the TC unlocks and the tranny seems to free wheel after that. There also seems to be more going on too like rough down shifting or somthing that can be felt. Watch your tach and you should see the RPM's drop down after you remove your foot from the throttle. Transmission programming needs some work on this engine/tranny configuration IMO. I've been complaining to Chevy about it but I'm only at the beginning phase. I don't know if all cars do it and only some people notice it or what. My Chevy mechanic notices it and wrote it up on a service ticket and then drove another on the lot and said it was even worse. He is trying to get the district engineering involved to try and figure out a solution. Really pisses me off as the 4spd does not do this.
 

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Seems like the same thing as our still long running Malibu shudder thread...either/or a shudder on acceleration especially in a certain speed range and strange shakes, surges, etc. on deceleration. All with the 6-spd, V6 and some 4-cyls.

The '09 2LT I had, and which caused me to be a big part in our shudder threads and such, had a shudder throughout the car from 40-55'ish accelerating lightly and then anytime decelerating, was just rough with very noticeable surges, tach/rev spikes and dives, and other weirdness when decelerating. And not always the same, sometimes even gone, depending on the day--such as when the GM engineers came to test it, of course.

Look here:

http://www.chevymalibuforum.com/forums/showthread.php?t=1663

http://www.chevymalibuforum.com/forums/showthread.php?t=906

It can be a little different for different people and cars, but the same basic issues are the same.
 

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It can be a little different for different people and cars, but the same basic issues are the same.
I had read these threads as I noticed a rumble or shake in my LTZ when I was driving between 40 and 50... that seems to be better. This is more a lack of ability to coast -- worst than that, it feels like the brakes have been put on.

The "shudder" I notice is most likely the tranny finally unlocking as Blu-bu said. I have to think I'd be getting better gas mileage if this car didn't do this...

I'm going to take it in to have them work on a mildew smell (again) and the recall... will have them check this too.
 

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Its basically like a jake brake. The low low gearing in 6th gear actually slows down the car if you are trying to go down a moderate hill while coasting.

Its just something youll have to live with in the 6sp.
 

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Its basically like a jake brake. The low low gearing in 6th gear actually slows down the car if you are trying to go down a moderate hill while coasting.

Its just something youll have to live with in the 6sp.
Can the "low low gearing" in 6th gear be reprogrammed?
 

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No, it cant. Its the actually gear ratio thats so low that it lugs the engine.

In my Formula I have a 6 speed manual and its 6th gear is a .50:1. Its A LOT lower than the .742:1 in the Malibu.

The only difference is that my engine makes more HP so at a lower RPM it can still coast downhill and uphill without changing gears. At 70 in my car im turning around 2100 RPMs and the car makes about 150-160 HP and around 270 TQ. With that amount of power it can "lug" the car up a hill easily.

With the Malibu the 4cyl makes around 40-50 HP in 6th gear and the 6 cyl makes around 60-70 and that just isnt enough to lug a 3600 lb sedan up a slight hill so it downshifts to 5th where it gets the RPM up higher so the car can make more power to get it up the hill.

However, I will tell your dealer that the car isnt downshifting when going up a hill. Thats a huge problem for you and the car.
 
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