Warble sound occasionally
 

Car is new, less than 200 miles and at times i hear a warble sound, not sure if its tires road noise or what. Seems to make the sound when accelerating mildly after up to speed. Any thoughts or is this normal tire road noise. Thanks

I had it too but it only happened once then went away never to return. Never did isolate it.

get it every now and then, don't pay much attn. to it. do for oil change ill mention it but I doubt they can repeat the issue.

Not much response so we must be the only ones with the issue. Please post up any info you get after oil change. I hate hearing this unusual noise on a 65 k plus car. I don't seem to notice it if i get into it or just steady cruising speed. Thanks for the replies.

warble sound
 

I have 3,500 miles on my 2015 c7 base and hear the sound you have identified as well. It appears to be coming from the left rear tire on certain roads and diminishes when either slowing down or changing lanes. It is perplexing as I have no idea as to what may be causing it. Will be taking it to the dealer for my 1st oil change tomorrow as the message " change oil " flashed on the instrument panel which is also of concern. However, in an attempt to solve the warble problem, I checked the level of the differential and found it to be an inch below the fill hole. After having the dealer correct this, I will let you know if this corrects the problem. Til then, best of luck.
Ralph

This is exactly how my vette sounds. As to the fluid level this maybe normal. I know on my c5 that was normal. Look forward to your dealer resolution and your update to the post. Thanks for responding

I too have a noise coming from what might be the driveline, or Exhaust. I have a couple of posts on this going now...... ONLY happens when my foot is on the gas pedal, usually lightly.... not flooring it. If I take my foot off the gas and coast, the noise goes away immediately. Does it in ALL driving modes. I have NPP and Mag ride.....

Anyone else ???? I haven't taken it to a dealer yet, as it's a subjective sound.

I meant to add that I too seem to hear it from my LEFT ear..... sounds like it coming from the Left Rear wheel area.

Me too. Next oil change I will have it looked at. Mine is 2016 base A8

We also have a base 2016 NPP, Mag Ride, A8....... Please post any updates. We just turned 1k miles so WAY too soon for an oil change. ONLY seem to hear it from my left ear. Other forum member said the same thing,,,,,,, but he traded his ride for a new Z06

thanks,

V4 to V8 noise
 

Hi Strake,

I have been meaning to respond to your post for a couple of days now... but been too busy having fun with the Vette. Warning - long post as I like to be complete in my descriptions.

Base 2016, NPP, MAG, A8, 600 miles - and I have had what I call a chirp since day one. It usually happens at 45-50 MPH, 1400-2000 RPM, and only when going from V4 to V8.

I give it just a little throttle and can extend the amount of time it chirps (I like the comparison to a warble too) by just barely keeping it from going to V8 mode. If I get on it a little more between V4 and V8 it will just give a brief chirp and then be in V8 mode.

I took it to the dealer 3 weeks ago and had the service manager ride along with me. He heard the noise and discussed it with his mechanics. They took another car on the lot out and did not hear the noise, so they said it was not normal. I don't know if there is a TSB out on it or it they just talked to Chevy, but they said they were told to replace the muffler assembly (specifically a valve that is in the assembly). This matched was I had found on the internet with some Tahoe owners with the 6.2L V8. They said the adaptive valve was to blame. Of course, on their vehicles you could look under the back end and see the valve, so they locked theirs open to get rid of the noise. Not sure if the Vette has direct access to this valve or it is in the muffler.

They got the new muffler assembly in and this Friday I dropped the car off at the dealer for ~5 hours (they gave me a rental). They did the swap and said the mechanic and service manager went out and could not hear the noise any more, so they were claiming success.

I drove off and a couple miles down the road I still heard the chirp. It was not as loud and usually of a shorter duration, so it is improved but not fixed yet. I needed to be somewhere, so I didn't just turn around and go back to the dealership. I will call them on Monday and see about getting another replacement muffler assembly.

On the Tahoe forum I saw people saying they needed 3 replacements to get rid of the issue. But this was back in 2014 (and likely a slightly different component). So I am hoping that third time is the charm for me and I don't need to deal with this thru too many more swaps. The first muffler the noise was quite loud and happened frequently with how often the AFM kicks in. It was really loud with the windows open.

I have seen several people now on this forum bringing this up. It seems sort of a recent item (everyone had a new 2016 A8 NPP if I recall). So they may have a bad batch of valves or slightly tweaked the design recently.

I'll update here with what I find out on Monday.

WOW...... Arctic, thank you for the insight..... you are one of the first to have any real feed back. THANK YOU...... please let me what you find out next week. I'll wait to see what the outcome is and then visit my local dealer. I even tried recording the sound, but it comes through pretty quiet on the recording. By any chance, were you hearing your noise out of your left ear ? I definitely hear the sound from the left rear .....

I went out for a ride tonight and did some left right left right pulls on the wheel just for kicks and didn't seem to hear it again. Mine doesn't sound like an exhaust valve issue but who knows. Mine is not a chirp but a warble type sound. Glad to hear i am not only one, misery loves company. Maybe one of us will stumble onto a fix. Thanks for replying guys.

My 2014 A6 had a chirping noise - only it came from under the hood. The problem was a faulty drive belt tensioner. It was a common problem for some automatic 2014's. There was a TSB on it and it was repaired under warranty. The noise only happened going from V4 to V8 under light acceleration. Sounds similar to what you are describing but not from the left rear. I had it repaired and the problem has not recurred.
Good luck finding the cause of your noise and for a proper fix.

By the way, I LIKE your description of the sound as a "WARBLE"..... I was grasping for a good descriptive word. I was calling it a scraping type sound, but knew that wasn't a good choice of words.

Are the cars with this issue all 2016 A8's?

I have a 2015 A8 that had a stutter in V4 mode that turned out to be the dreaded 3 day Torque Converter repair issue. It's being replaced as I post. If it is only happening on 16's that were built after 11-1-15, perhaps it's in the new TQ and no real issue as far as reliability.

Mine is a 2016, A8, NPP, with Mag ride....... Built 1/26/16

Visited the dealer on 4/11/16 for several issues one of which was the low differential fluid level. This was a very disappointing trip for several reasons as this was the issue I wanted to address for the reason that if this were the cause of the warbling, we would be so much happier. If it were not the cause, other issues could be sought. The service adviser stated that the mechanic said the level was OK which I knew to be false. He then said that it could not be filled by adding fluid via the top fill hole until it starts to drip out of the lower hole since this would essentially dumping fluid on the floor. My reply was that the idiot who said that was a janitor and surely not a mechanic as there is no other way to ensure a complete fill. I will obtain a quart of Dexron LS gear oil -GM #88862624 today and let you guys know what the findings are. As many of you will understand, this will be the last time this dealer will be used by me. In the meantime, whatever service needs to be accomplished that I can do, I will do including oil changes as mentioned on another post whereby there is no one I trust more to change oil in my vehicles than me. Be well.
Ralph

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.

I googled the adaptive valve on the chevy 6.2 truck and one post said there was a TSB on the issue but no # for it. Those guys wired or bolted their valves open as a way to test and see if this stopped the noise and it did. Some replaced them others took them out completely of the system. From their picks of the valve it looks to be different from the vetts if I am looking at a the correct valve. Their valves worked off of pressure and had a spring to close when exhaust was operating normally. They did mention greasing the valve. I crawled under my vette and there is a valve on each tail pipe just forward of the muffler, I assume this is the component we are talking about. It is welded into the system and has what appears to be an electrical connection and wire leading to it that I assume actuates the valves when certain parameters a met. I don't see any way to grease it or force it open and secure it but limited space to get a good look at it. I have a pit in my shop and I will try and get a pic of the valve I believe to be in question so all can see. I went on a 150 mile road trip yesterday and could hear it really well and I am not sure it is associated with 4-8 deal, it may be but hard to tell. Seemed the longer I drove and hotter the car got the less noticeable it was. I have an oil change coming up in a few hundred miles and would like to have some good info to share with them on the issue because my dealer is very small and I doubt they work on many vettes. Thanks for posting you findings and keep them coming. Arctic they did replace your muffler system and did U see the valve in question?? The valve I am seeing is upstream and separate from the muffler so I don't think replacing the muffler would accomplish anything but what do I know. I maybe looking at something else but don't think so. My vette started the sound on the second day, first day was quiet as a mouse. Thanks

Is it AFM switching between 4 and 8 cylinder modes? I would describe it as some marbles in a can type of sound when that happens. You can set one of the info dials to instant fuel economy, and it shows when the cut over happens, and the noise always happens during the swich in mine.