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Discussion Starter #1
I don't want to scare anyone, or be negative, but I wanted to ask if anyone else has this issue:

When AFM kicks in, it's very noticeable (thump), and it makes an awful scraping sound sometimes. It sounds like a small tin pail being dragged across the road. It's not very loud, but you can hear it if the radio is off.

Also, I have my exhaust valves set to be open all the time, but they still close at cruise in all driving modes except for track. Is that normal?

Vin 0286
 

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Sorry, but something isn't right with your AFM system, especially after reading folks post that they can barely tell when their car is going in and out of AFM mode. regret that you will need to take it to your dealer. Hopefully it is something quick/easy to fix for you.
 

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Discussion Starter #3
Sorry, but something isn't right with your AFM system, especially after reading folks post that they can barely tell when their car is going in and out of AFM mode. regret that you will need to take it to your dealer. Hopefully it is something quick/easy to fix for you.
Thank you. That's what I was afraid of. At least I'll have the pleasure of driving one the dealerships finest chevy spark rental cars for a week : /
 

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I can tell each time it changes from 8 to 4 and back, i can feel it and hear it. The sound is just like you describe and it's nowhere as smooth as how my 07 Ram was. However, I think it's ok and normal for this car. The sound is the pitch change and it resonates differently in each mode. The exhaust is designed specifically for these sounds and if it not perfect you can "feel" the sound change as well.

For example, on my Ram the system changed almost completely unnoticeable but when I changed the muffler and cut out the rear resonator in the exhaust it changed the sound on the exhaust when it was in 4cylinder mode in a way that it felt like more vibration and transition from 8-4-8 was much more noticeable and annoying.
 

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Discussion Starter #5
I can tell each time it changes from 8 to 4 and back, i can feel it and hear it. The sound is just like you describe and it's nowhere as smooth as how my 07 Ram was. However, I think it's ok and normal for this car. The sound is the pitch change and it resonates differently in each mode. The exhaust is designed specifically for these sounds and if it not perfect you can "feel" the sound change as well.

For example, on my Ram the system changed almost completely unnoticeable but when I changed the muffler and cut out the rear resonator in the exhaust it changed the sound on the exhaust when it was in 4cylinder mode in a way that it felt like more vibration and transition from 8-4-8 was much more noticeable and annoying.
Ok thanks very much. I will say that I did not notice the AFM sound until I recently stopped playing music. I'm now more interested in the exhaust note.
I'm still going to take it in, because I have the variable crazy screen syndrome.
 

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I'm going to say that is not normal.

Even on the camaros with AFM, if you swap out the factory resonated system to a non resonated aftermarket system; you get a burble in the exhaust during AFM activation. But not a screech.
 

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In one of the displays it will actually tell you which more you're in V8 or V4. It's interesting to watch it change.
 

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Discussion Starter #8
In one of the displays it will actually tell you which more you're in V8 or V4. It's interesting to watch it change.
I actually did that today. I was going 40 mph and it kept changing back and forth from V4 to V8 for no apparent reason. I wasn't accelerating or anything. That noise I described was happening when AFM was going on and off.
 

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Discussion Starter #9
I'm going to say that is not normal.

Even on the camaros with AFM, if you swap out the factory resonated system to a non resonated aftermarket system; you get a burble in the exhaust during AFM activation. But not a screech.
That's true, my last car was a camaro ss automatic and the AFM worked so well I never knew it was there until I put a different exhaust.
 
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