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Discussion Starter #1
chevy.jpg Hello! Thanks for this great forum. I picked up this CPO 2012 LT fleet for a very good price about a month ago (Love that first year depreciation!). I'm enjoying the power and comfort, and still getting used to the car. I have noticed a couple of issues. There is an unusually loud noise from the engine or exhaust when I'm accelerating under load from a stop or low speed. It sounds like an exhaust leak or even a possible restriction, although none has been found. There's not a distinguishable knock or tap, but more of a breathy, muffled growl that has a rhythm to it, but it's loud and unnatural enough that it makes you immediately think something is wrong under the hood. This almost new family car shouldn't sound like it has a Holley 650 with all barrels wide open, when I'm just pulling out of my driveway. Both the service department at the lot where I bought the car, and at a GM dealership have looked at the car and both said that's just the way the car sounds. I find that hard to believe, but so far I'm not educated enough about the car to argue with them. This noise only happens under load, and it smooths out and disappears above 2500rpms. There is a definite cadence to the noise that changes with the rpms. I've eliminated it being associated to any suspension parts. The noise only happens under load. When in neutral or park, the engine revs smoothly and no noise can be heard, and the transmission seems to be working correctly. My second issue is with the starter. The starting is rough. It knocks and shakes pretty hard when you crank it. Usually a couple very rapid shakes, a thump or two all within a quick second, then it starts up. It has never failed to start, but it definitely seems like there's a problem with the teeth alignment and it almost feels like it's trying to bind up for an instant before it angrily starts the car. I've done some research and asked the service departments about possible starter/flex plate issues, wondering if these things are related, and if there's something throwing things just a little out of balance under the hood, but no one has been willing to tear into the car to see if there are any deeper issues. The car seems to be firing just fine with no misses. I have about 5k miles left under factory warranty, and am anxious about not getting my issues addressed before my warranty expires. Any opinions or advice would be greatly appreciated.
 

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Back in Black
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Starter should be smooth have them check that the starter is on good no loose bolts.
Single or dual exhaust? You might be hearing the direct injection sound a little like diesel engine just nowhere as loud as rmp's go up you can't hear it over exhaust.

Welcome also. Nice pic's too.
 

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Welcome!!!:beer:Thanks for posting PICS!!!:eek:k3:
 

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I believe I know what your talking about I have a 2012 LT and makes same noise if I'm understanding it. Sometimes the noise is louder than my flowmasters than when he get moving good noise goes away than you hear the flowmasters.
 

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Discussion Starter #6
Thanks everyone, and thanks Rod for your feedback. It does have dual exhaust. I have been told that the starter was checked out, although I know it was not removed and inspected, just checked for secure external mounting. I will definitely be picking my own certified Chevy dealership to take it back to, and have it looked at more closely, if they will do it. So far, I've been told that it's a design issue and "all of the 2012's start a little rough", and no one has been willing to acknowledge that there's anything wrong, let alone actually remove the starter for a closer look. Frankly, I'm just not satisfied with that.

About the noise under acceleration, I have read online comments from maybe 4 or 5 other 2012 Impala owners who have also mentioned the noise I'm hearing. I have also read many comments from 2012 owners who talk about how quiet the car is inside, which continues to nag at me and makes me think I have some type of weird exhaust back-pressure, or something in the exhaust system has burned out internally, leaving a loud but muffled noise that sounds like an exhaust leak. Strange that it only happens under load, and smooths out at higher rpms. I am hoping that some other 2012 owners like Rod will see this and speak up if they are experiencing the same and are worried that no one seems willing to address it. I really love the car, and if the sound it makes is the way it's supposed to sound, then I'm okay with that. So far, everyone who gets in the car and rides with me, including the service manager at the car lot, has immediately noticed the sound and also found it unusual. Besides this couple of issues, my Impala is a BEAST! Soft ride and muscle under the hood is a winning combination for me, as I spend a lot of time driving. Thanks again for this great forum!
 

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LIFETIME HILLBILLY
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Welcome to the forum!
 

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Our Impala has had a nice growl from the rear pipes since we took delivery with 88 km's on the odometer - car was a special order with a bench seat.

All the 2012's with the direct injection 3.6 have dual exhaust

From day one, when I have started the car, it fires right up almost instantly, but the RPM visibly "hunts" on the tach by about 300 RPM in about half second intervals. This is inside my heated attached garage. Outside, much more noticeable. The engine shakes while doing this too.

I have tried different brands of gas here - Esso, Shell, Mohawk, PetroCanada, from 87-91 octane, with no difference whatsoever in the cold start roughness.

The dealership is aware of this, has documented it, and has said they all do it. He had 6 other '12's on the lot and he let me cold start all of them. They all did the same thing. I have to assume that is just how direct injected GM V6 motors behave.

Really, really like the car. A good commuter car and highway cruiser, great fuel economy for the size. Incredible power. With the studded snow tires, a great winter car too.
 

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Discussion Starter #12
Thanks all! Thank you jay for your comments. It doesn't get very cold where I live, but I have experienced the same cold start idling with my 2012. I think, however, we might be talking about different things. I believe you are referring to how the car behaves while idling after a cold start. My issue is with the actual starter itself feeling as if it's loose and trying to bind up, and knocking/rattling/thumping when you turn the key over. It almost sounds & feels like something is bouncing off a cross member or the floorboard underneath the front end. Something is making contact, you can feel it. Also, my car has a nice sound from the rear pipes as well. However, mine also has an unusual noise from the front end when accelerating, that sounds related to the exhaust system. I'm going to try to post a video in a bit to demonstrate the sound from inside the car. Thanks again for your comments.
 

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8th Gen Antagonist
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Welcome!
 

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Billalmighty, welcome to the forum! And thanks for all the great pics of your Impala! If you ever have vehicle questions, would like assistance working with your dealership, or even would like a copy of your build sheet, please let me know. I'm reachable via private message through the forum and happy to help where I can!

Best,

Katie
Chevrolet Customer Service
 

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8th Gen Antagonist
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Upload it to youtube, and post the URL in your message, don't use the embed link because it doesn't work, use the actual URL.
 

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Discussion Starter #18
The rattling/popping sound of the exhaust under load around 15 seconds, and again from 48-60 seconds seems unnatural for this quality of car and engine, and today's technology. It sounds like something is wrong. I can't tell if it's exhaust related or maybe even a plastic shield rattling loudly against something? Does anyone else who owns a 2012 recognize this rattle?

video-2013-03-10-13-09-19 - YouTube
 
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