bjones7131

Update, took car in, we drove and serv. Manager heard the noise. Contacted gm eng. And was instructed to disconnect the NPP performance exhaust valve actuators. They unclipped the wire fastener at the valve actuator so they were open all the time, they took a ride and thought they had found the problem and pin pointed it to the passenger side. I drove the car with the tech. And got the car to repeat the sound but it was really faint and i had a hard time getting the car to make the noise, it does it best when at 1500 rpm on incline with slight increase in throttle. Informed serv. Manager noise was still there and he said gm told him to order and replace mufflers and NPP valves. They don't think it is the AFM valves, eng. Said they had, had problems with the NPP valves. I could live with the slight noise as is if not for the drone sound in 4 cylinder mode with the NPP valves disconnected. I will update again when new exhaust is installed.

Highplains

GM appears to be wandering aimlessly on this. Your experience is a repeat of what others have reported with the end result of their fixes not working. It’s my personal opinion that the problem is in the exhaust system but enough people have had it replaced with no success that you’d think GM would be looking at the components they’re using to see if they’ve got a large supply of defective parts that they just keep sticking in on the assembly line. As such, I am hopeful that they can find a fix because this thing just keeps dragging on.

RichAshley-Black99

I have the same exact issue my car now has 10200 miles, they replaced the transmission at 5k back in sep 0f 2015 thinking that was the issue. Didn't fix it, we drove a brand new 15 they had on the lot and it did the same thing. So anyhow not happy its still there. I need to take it back in at some point. My car does not have the NPP option.

bjones7131

I agree and i told those guys unless they knew the replacement components were working properly and in fact this is the issue, why put bad parts on to replace a bad part. Insane

Highplains

Any updates on the warble, 1500 RPM sound?

bjones7131

Nothing to report, dealership was going to order a new exhaust system but haven't heard from them. I need to see where they are on the order.

bjones7131

Dealership got new exhaust system in last week and I have an appt Wed. the 20th. I was at the dealer I purchased my vette from last week and he said GM had a stop hold on any exhaust systmes going out until they solved the problem. Not sure if that is true or not but the other dealer ordered and got in a new system for my car. We will C. I will report back after installation. Any other updates from U guys with this problem?

Highplains

Have heard nothing. Service manager does not return calls or email. I don't think he'll fart unless GM lets him so he is passively waiting for a TSB to come in.

DickieDoo

See thread above... with link to Service bulletin... Bulletin PIP 5185

"A6 AFM problem.... advice needed"

they should at least check this as the "warble" sound sounds similar !

Highplains

Thanks for your input. PIP 5185 refers to a belt tensioner problem that occurs when the vehicle switches from 4 to 8 cylinders. Those of us with the so called warble sound have pretty well eliminated that as an issue. This sound occurs primarily as the tach goes through 1000 and again at 1500 RPM and from the rear of the car. Many, myself included (with a Range Technology device), have observed the problem in all drive modes, AFM mode and all gears-even reverse.

bjones7131

Update: Took my car in Wed. and they replaced the AFM valves, Mufflers, and NPP baffles and noise is still there, no change. They removed the rear bumper to access the exhaust system and had to send it next door to the body shop to re-allign the bumper/panel and I am supposed to pick it up later today, hopefully. What a feasco. Service manager said they would go back to GM tech support/eng. and see what they want to change next. This looks like a really ineffecient way to do business to me, these dealerships and GM have become parts changers. This is a very expensive way to do business. This exhaust system prob. cost 2-3K plus labor. I am convinced this noise is in the drive train somewhere. This dealership is approx. 70 miles(round trip) from my home and I will make 3 trips when all is said and done to pick up my car with no resolution plus at least 14 hrs of my time hanging around the dealership. I may trade this thing in on a mustang. Customer Service if U R monitoring this post, we need your support, very unhappy camper.

Strake

Very discouraging news. Sorry to hear... With three attempts to fix this, try the Lemon Law scenario on them. Like you said, all the dealers seem to do is throw parts at it. Terrible way to address issues.

I've still done nothing.... but we've been gone about half the time without the Vette. I was hoping this was the answer..... My local dealer Service Writer is convinced it is in the driveline, as I am too. I told them I thought it was the driveline from day 1. This is what I didn't want to have to deal with, so I sat back and hoped the exhaust system was the issue.

Richard

Highplains

I'm like Richard. I'd hoped that something would come of your attempted fix. With this, I'm also back to thinking its the drive line. If nothing else, I don't see how harmonics or vibrations could occur at just about the same RPM in all of the cars reporting this. Assembly lines can't be THAT uniform. However, lousy parts and/or poor design can be uniform. My theory, FWIW, is that it may have something to do with too high a gear at that RPM and that the engine, loaded with low-end torque or not, cannot accommodate the stress subsequently putting a strain on some drive line component(s) that are rattling in protest. At the same time, however, I have read of people who have had their entire drive lines replaced including torque tube, tranny and diff. I wish someone in GM, including my Service Manager, would get a little more proactive on this before something serious breaks. I'm also thinking that GM hopes we'll all just go away. maybe a Mustang is a good solution. I'd be thinking Camaro but wonder if its got the same thing. There's a bunch of new Camaros in this town and I may start flagging down some of them to see what their experience is.

Highplains

As a follow-up to the previous post, I forgot to mention that I had called one of country's largest Corvette dealers to see if they had had any experience with folks complaning about this noise. The person from service said he'd "research it" and get back to me. I'll let you guess as to whether he called me back or not.

bjones7131

I am convinced it is a drive line issue. If U listen closely U can hear mine at very low speed/RPM when I am easing out of my driveway. When I test drove mine after the exhaust install I barely heard it while exiting the dealership lot and I knew then that my problem was still there. As I got on the road and at 1500 RPM is really showed up. Serv. Manager said bring it back in and he would call tech support and change more parts as they directed. I don't know whether to let them tear into my car on the driveline or not. Between a rock and a hard place.

Highplains

If you decide to have them work on the drive line (and they O.K. it) you may want to find out if what they're planning on installing has been improved with this problem in mind rather than their just throwing more of the same old stuff at the car.

bjones7131

Update: I started a post on FB C7stingray group and a guy actually has a video of this and it is spot on for my car is doing. A guy by the name of Mike Davenport chimed in and you may have heard of him on the forum he is the chevy problem solver guy from Lousiville chevy. He is going to get his guys in their shop on it. I just got my car back from body shop, they screwed up my rear bumper changing out the exhaust system. Nothing major just needed some realliging so the body lines were like the day I got it. They kept in all this week but it is prob. 98%, I can live with it. Lastly are we all talking about the A8 tranny or are there M7's as well on this post with this problem?. I hope Mike Davenport can shed some serious light on this. Thanks

Strake

Bruce,

I'm guessing that is Face Book..... you are referring to ??? I don't do face book.... any way you can PM me a link so I can hear the video clip too?

A8 trans for me.

thanks,

Richard

Highplains

bjones:

I went to the C7 Stingray FB group and listened to the video posted by Glenn Eaves. His noise is EXACTLY what I am experiencing. I haven't heard that noise recorded yet that is most like mine until now. I'm really hoping that we're on the way to pinning this down. It looks like we're going to have to do this because GM sure isn't.

Strake

Highplains,

without a Face Book acct, I'm unable to locate the video clip. Any help to gain access to it by you, or Bruce is greatly appreciated.

thanks,
Richard