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Discussion Starter #1 (Edited)
2012 Impala LTZ
3.6
I know there are tons of these threads but none fit my problem.
Shaking starts around 60-75 MPH under slight load. I can do the manual shift down into 5th and it will usually go away. The RPM range I have found for this is 1300 to 2000.
I have lightly pressed the brake while maintaining speed and the shake was evident up to the point the brakes started grabbing and I let off the brakes.
I cannot get it to shake while stopped in neutral or drive.
I do not feel the vibration or shake in the wheel.
As soon as you lift off the gas the condition goes away immediately.
Fluid levels are all good.
Raising RPM above 2000 will make it go away.
I can get it to stop for a short period by shifting to 5th and back to 6th but I can get it to shake in 5th if I leave it in that gear.
Gas mileage is not affected.
Temperature is normal.
Motor mounts appear good.
Weaving the car right and left does not stop the shaking.
I can see the tach bouncing 100 rpm during the shake.
There are no codes.
 

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I'm not sure what the "3800" line is in the second line of your posting. The 2012 Impala did not have a 3800 series engine - it came standard with the 3.6 HV V-6.
 

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Discussion Starter #5
If the tire balance was the issue I would think the engine RPM would not factor in. This is only under load, I wont an out of balance tire shake between specific speeds whether applying power or coasting? I need to find a way to check the CV joints, they aren't making any noise at all.
 

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Agreed - to me, it doesn't sound like a tire/wheel issue if the issue goes away as soon as you let off of the throttle...

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Fuel injector? I had a similar issue with my Ford. I could only get it to run smoothly running in a lower gear and higher RPM. It was chugging and bucking at the low RPMs. It was a bad fuel injector.
 

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Discussion Starter #8
A new update.
I was able to find time to crawl under and check some things. Found the inner CV joint had some funny play in it. None of the parts stores carry the axles yet and the dealer needs 450 for one. I ordered a new one through rock auto for 80 bucks. Installed the new axle and the found this one to have the exact same play in it. Making sure I wasn't losing my mind I drove it and could duplicate the original issue with the same conditions. Does anyone know anything about bad bearings in the transaxle?
 

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Discussion Starter #9
If the injectors were bad would the problem have a certain rpm range? It goes away above 2000rpm and is not there at all under heavy load. I'm dumping in a can of seafoam today, I know it wont bring back a dead injector but a slight clog maybe.
 

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Mine does the same thing exactly what your saying. I was figuring it was the torque converter but didn't want to spend the money but now I know thanks bro.. Saved me a lot time to start working on the impala

If the injectors were bad would the problem have a certain rpm range? It goes away above 2000rpm and is not there at all under heavy load. I'm dumping in a can of seafoam today, I know it wont bring back a dead injector but a slight clog maybe.
 
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