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Old 04-17-2016, 08:23 AM   #21
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Same - 2016, A8, NPP, with Mag ride. Built 3/7/2016.

Went back to the dealer today - 3rd time for this issue (1st was ride along and service manager heard noise, 2nd time they got a new exhaust and installed it, 3rd time today to have another service manager ride along to hear that the chirp noise when going from V4 to V8 is still there). This time they also had me drive a similarly equipped car and it didn't make a peep. So they agreed that it is not normal.

They are going to do some some homework and consult with GM about what to do next.

The first time they tried a valve lubrication that was described by GM, if that didn't work (which it didn't apparently) the advice was to replace the exhaust. My belief is that they should order another new exhaust and swap it out, as the first new one seems to have the same issue. My wife and I agree that the first exhaust swap cut the noise down by a fair amount, but didn't get rid of it.

I will continue to update as progress occurs in the hopes that it can help anyone else with this issue.
What is the name of your dealership and where is it located just in case my small dealer wants to consult with them on your fix. Thanks for the feedback.
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Old 04-17-2016, 01:24 PM   #22
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Relating to the pesky and aforementioned warble problem, I had dealer rotate the tires - obviously side to side - and returned home to add Dexron LS fluid to the fill level. Then drove on the same roads where the warbling sounds were heard and experienced no problem. For what it is worth, this not being an exact science it could be left to coincidence or any one of the two corrective measures above. Best of luck to all who are experiencing this problem.
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Old 04-18-2016, 08:29 AM   #23
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Here are two picks of the valve in question



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Old 04-19-2016, 10:14 PM   #24
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What is the name of your dealership and where is it located just in case my small dealer wants to consult with them on your fix. Thanks for the feedback.
Hey BJones,

I go to Rick Hendrick in Duluth, GA. They said that they talked with the GM tech center. It sounded like the tech center had a valve lubrication process followed by an exhaust replacement if the lubrication didn't work.
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Old 04-20-2016, 04:23 PM   #25
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I took my car in for a 500 mile oil change and mentioned the warble sound. Service manager and lead tech both rode in the car and both heard and acknowledged the sound. I shard the info on the adaptive valve and they were aware of the issue with the trucks which is a different type valve, truck is a spring check valve and the vette has electrical operated valves so not sure lubrication would help. They said they would contact tech center for resolution. The said swapping the valves out with mine being a new car that more than likely any new replacement valve would have the same problem. GM engineering needs to find a fix and upgrade the valves before swapping them. This made sense to me so I will check back with them later to see what they found out. We may have to keep documenting this issue through our dealership and let them contact GM for a resolution. Please respond with any feedback U have on your cars. Thanks
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Old 04-20-2016, 05:52 PM   #26
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Hey BJones,

I go to Rick Hendrick in Duluth, GA. They said that they talked with the GM tech center. It sounded like the tech center had a valve lubrication process followed by an exhaust replacement if the lubrication didn't work.
If they fix yours, i am not but 1.5 away so i may have them have a go at mine sinse they are knowledgeable with the problem and changeout process. Thanks
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Old 04-20-2016, 06:19 PM   #27
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I took my car in for a 500 mile oil change and mentioned the warble sound. Service manager and lead tech both rode in the car and both heard and acknowledged the sound. I shard the info on the adaptive valve and they were aware of the issue with the trucks which is a different type valve, truck is a spring check valve and the vette has electrical operated valves so not sure lubrication would help. They said they would contact tech center for resolution. The said swapping the valves out with mine being a new car that more than likely any new replacement valve would have the same problem. GM engineering needs to find a fix and upgrade the valves before swapping them. This made sense to me so I will check back with them later to see what they found out. We may have to keep documenting this issue through our dealership and let them contact GM for a resolution. Please respond with any feedback U have on your cars. Thanks
Thanks !!!!! I haven't taken our car in to a dealer yet, as I'm no where close to needing an oil change and was hoping someone who has already has made progress on this issue. I'm tied up for the next few weeks and if no one has seen a fix, I'll also take our's in. Not the delivery dealer, (Kerbeck), just a local, friendly, very small dealer ( who had NO allocations at order time). They do have 1 Corvette mechanic.
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Old 04-26-2016, 06:36 PM   #28
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Anyone taken your car in for a fix on this issue. Please update if U have, lets not let this thread die without exhausting all our efforts to get this issue solved. Maybe someone can explain how this valve works when going from 4-8 cylinder mode. I thought the valve was supposed to make the transion quiet not make the noise we are experiencing. I assume this valves closes somewhat then going to 4 cylinder mode and open wide open when in 8 cylinder mode. I am no eng. but I don't see why the car needs this valve at all. The car has to breath/exhaust no matter what mode U R N so I don't get it. Some of the truck guys with the 6.2 took the valve out completely. Thanks
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Old 04-26-2016, 06:44 PM   #29
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Pull fuse 32 from under hood fuse box. That controls the AFM exhaust valves. This will let you determine if the valves are for certain the source of the "warble". It will also let you hear what the exhaust sounds like without these valves actuating when it switches to V4 mode (I've been told it sound terrible).
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Old 04-26-2016, 07:16 PM   #30
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Pull fuse 32 from under hood fuse box. That controls the AFM exhaust valves. This will let you determine if the valves are for certain the source of the "warble". It will also let you hear what the exhaust sounds like without these valves actuating when it switches to V4 mode (I've been told it sound terrible).
Will the valves fail open if I pull the fuse, again the motor has to breath/exhaust so I don't want to damage the motor. I assume this is the way it was designed should a valve fail or becomes damaged or a fuse is blown. I know we aren't engs. but i am a detail guy and I have heard many many 4 cylinder motors and no crazy noise. Obviously there is a lot I don't understand about these valves. I suppose you could purchase one of those devices that eliminates the 4 cylinder mode and I assume this would stop the noise I speak of. Go figure. Thanks for the suggestion
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Old 04-26-2016, 07:26 PM   #31
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Will the valves fail open if I pull the fuse, again the motor has to breath/exhaust so I don't want to damage the motor. I assume this is the way it was designed should a valve fail or becomes damaged or a fuse is blown. I know we aren't engs. but i am a detail guy and I have heard many many 4 cylinder motors and no crazy noise. Obviously there is a lot I don't understand about these valves. I suppose you could purchase one of those devices that eliminates the 4 cylinder mode and I assume this would stop the noise I speak of. Go figure. Thanks for the suggestion
Many have pulled both the AFM fuse and the NPP exhaust fuse so they get "loud" exhaust at all times. The "un-energized" state of the valves is for them to be open.
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Old 05-02-2016, 08:28 PM   #32
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Anyone taken your car in for a fix on this issue. Please update if U have, lets not let this thread die without exhausting all our efforts to get this issue solved. Maybe someone can explain how this valve works when going from 4-8 cylinder mode. I thought the valve was supposed to make the transion quiet not make the noise we are experiencing. I assume this valves closes somewhat then going to 4 cylinder mode and open wide open when in 8 cylinder mode. I am no eng. but I don't see why the car needs this valve at all. The car has to breath/exhaust no matter what mode U R N so I don't get it. Some of the truck guys with the 6.2 took the valve out completely. Thanks
Not sure what my last update was.

4/8/16 - Dealer replaced exhaust. Loudness of noise went down, but still present, even though they said they drove it and couldn't hear it any more.
4/15/16 - Went to dealer and had service manager ride with me, he heard the noise was still there. They had me drive another 2016, A8, NPP and there wasn't any noise, so they agreed that it wasn't a normal noise. Service said they needed to talk to GM tech center for advice on what to do next.
4/21/16 - Called dealer after not hearing anything. They said that it was with GM Brand Care (or something like that). I asked how long until I could expect a response and should I call back the next week. I essentially got a "don't call us, we'll call you" line about how they would update me when they got information back. Haven't heard anything from them since.

Based on recent suggestion in this thread I pulled Fuse 32 from the front fuse box and drove around. The noise was gone, but the Check Engine Light came on. I put the fuse back and the noise is back, Check Engine Light is still on. A couple other threads say it should go off after ~5 engine starts. https://www.corvetteforum.com/forums...ck-result.html

Seems pretty clear it is the AFM valves. I am going to call the dealer with this information and ask that they replace the exhaust again. If this is not typical (seems like it isn't since the other new Vette didn't make the noise) then it should be possible to get an exhaust that doesn't make this chirp.
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Old 05-02-2016, 08:44 PM   #33
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Not sure what my last update was.

4/8/16 - Dealer replaced exhaust. Loudness of noise went down, but still present, even though they said they drove it and couldn't hear it any more.
4/15/16 - Went to dealer and had service manager ride with me, he heard the noise was still there. They had me drive another 2016, A8, NPP and there wasn't any noise, so they agreed that it wasn't a normal noise. Service said they needed to talk to GM tech center for advice on what to do next.
4/21/16 - Called dealer after not hearing anything. They said that it was with GM Brand Care (or something like that). I asked how long until I could expect a response and should I call back the next week. I essentially got a "don't call us, we'll call you" line about how they would update me when they got information back. Haven't heard anything from them since.

Based on recent suggestion in this thread I pulled Fuse 32 from the front fuse box and drove around. The noise was gone, but the Check Engine Light came on. I put the fuse back and the noise is back, Check Engine Light is still on. A couple other threads say it should go off after ~5 engine starts. https://www.corvetteforum.com/forums...ck-result.html

Seems pretty clear it is the AFM valves. I am going to call the dealer with this information and ask that they replace the exhaust again. If this is not typical (seems like it isn't since the other new Vette didn't make the noise) then it should be possible to get an exhaust that doesn't make this chirp.
I was also told that if I drove around in the M mode that the valves were not in play or should I say completely open. I did this and still heard the noise. Try this and see if it has any effect. Did your car do it from day one. First day mine made no noise but I heard it on day two. I a have also heard you could get on of the devices (ranger) that plugs into the slot under coulumn and it disables the car from going into 4 cylinder mode. I communicated with a forum member who tried this and still got the noise and I know of another guy who has one on order to see if his noise goes away. Keep posting results and maybe we can get to the bottom of this. I am temped to pull fuse 32 and give it a try. When the 32 fuse is out the valves go wide open.
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Old 05-02-2016, 09:03 PM   #34
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I'm out of town and without our car till next week. Our car started making the noise about 40 miles from Kerbeck Dealership in NJ on our way home, day 1..... has done it ever since.

I too am very interested in getting to the root cause, and getting a permanent solution.
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Old 05-02-2016, 09:25 PM   #35
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I was also told that if I drove around in the M mode that the valves were not in play or should I say completely open. I did this and still heard the noise. Try this and see if it has any effect. Did your car do it from day one. First day mine made no noise but I heard it on day two. I a have also heard you could get on of the devices (ranger) that plugs into the slot under coulumn and it disables the car from going into 4 cylinder mode. I communicated with a forum member who tried this and still got the noise and I know of another guy who has one on order to see if his noise goes away. Keep posting results and maybe we can get to the bottom of this. I am temped to pull fuse 32 and give it a try. When the 32 fuse is out the valves go wide open.
I heard it from day 1 on way home from dealer.

I will try manual mode on the way to work tomorrow. If it keeps it from going into V4 mode, then my expectation is that the noise won't be there. I am almost 100% positive that the chirp I hear matches exactly with the V4 to V8 transition (I have never heard it going from V8 to V4).

I don't mind that it drops into V4 mode, from an acceleration standpoint it is barely noticeable. It is just the blasted whistle/chirp that I am tired of hearing.
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Old 05-02-2016, 09:39 PM   #36
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I heard it from day 1 on way home from dealer.

I will try manual mode on the way to work tomorrow. If it keeps it from going into V4 mode, then my expectation is that the noise won't be there. I am almost 100% positive that the chirp I hear matches exactly with the V4 to V8 transition (I have never heard it going from V8 to V4).

I don't mind that it drops into V4 mode, from an acceleration standpoint it is barely noticeable. It is just the blasted whistle/chirp that I am tired of hearing.
Let us know what you hear or rather don't hear in the M mode. Thanks
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Old 05-02-2016, 10:32 PM   #37
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I also have the chirping/squeak noise from the exhaust. It has gotten worse now and I think the baffles closes itself on occasional because when I downshift sometimes (auto trans, btw), the exhaust would stay silence like its in stealth mode. I took it in last year and the service guy said he couldnt hear it. Brought it in two months back and the guy heard the chirp/squeak but told me GM wouldnt fix it until the baffles fails or gets louder. I will bring my car to another dealership to have them look at it.

If you can hear it during the v8-v4 transition, try manually closing and opening the values through the setting. That way you can have the service people listen without having to drive the car.
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Old 05-02-2016, 10:38 PM   #38
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I also have the chirping/squeak noise from the exhaust. It has gotten worse now and I think the baffles closes itself on occasional because when I downshift sometimes (auto trans, btw), the exhaust would stay silence like its in stealth mode. I took it in last year and the service guy said he couldnt hear it. Brought it in two months back and the guy heard the chirp/squeak but told me GM wouldnt fix it until the baffles fails or gets louder. I will bring m
car to another dealership to have them look at it.

If you can hear it during the v8-v4 transition, try manually closing and opening the values through the setting. That way you can have the service people listen without having to drive the car.
How do u do that?? Thanks
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Old 05-02-2016, 11:43 PM   #39
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How do u do that?? Thanks
Go to your exhaust sound management setting and select the silence and sport mode. Keep opening and closing them to see if you can hear a chirp.
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Old 05-03-2016, 07:33 AM   #40
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You have some level of control of the NPP valves using this method. You have no control of the AFM valves which are upstream of the mufflers.

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Go to your exhaust sound management setting and select the silence and sport mode. Keep opening and closing them to see if you can hear a chirp.
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