Highplains

I've pulled fuse 32 as well as used a Range Techology device to keep it 8 cylinder mode as well as pulling the device so it will run 4 cylinder. Been through every mode and combination of gears I can think of including reverse and the noise continues. My dealer told me they have controlled the valves via computer when driving the car all without stopping the noise. The repost from Arctic C7 that bjones7131 posted leads my thinking back to the exhaust nonetheless. What a circus!

bjones7131

UPDATE: Took my vette in this morning for the appt the Chevy Customer Support helped set up although U don't need them to do that, was good to have another layer of support for our problem. My dealer and I talked about everything I have read on this forum post and he said they had contacted tech support and there was no issues or resolution as of yet. Tech support instructed the dealer to go through a short process while driving the car and see what results they got. Tech did this without me being in the car, I was up front office BS'ing, my bad. I think all it was was driving the car in different modes to see it there was any difference in the noise. They are satisfied that it is the AFM valves fluttering and making this noise we are hearing. Tech said he recalls another vehicle with similar valves having a recall that basically did a computer upgrade or flash that put more opening and closing force on the valves thereby eliminating the flutter/noise. This could be the fix but GM will have to make that call and their wheels turn slow. I like arctic think there supplier had a bad run of valves and we are the unlucky ones. They ruled out any drive train issues based on the way the car sounded and responded after driving it. Mine like all the others seems to be present and louder at 1500 RPM. I played with the car on the way to dealer and if I was in manual and using the paddles at times the noise went completely away and at other times the noise was greatly deminished in the manual mode. I told them about pulling fuse 32 which removes power from the valves and renders them open all the time and they said pull it and see what happens and i said you pull it and they said they didn't have time so I wasn't happy about that. I pulled it when I got home and I got no code like others said they did and but still a little noise but not as bad. My take is the valves are not seating tightly enough in the open or closed position and I think this baffle is inconsistant, meaning sometimes it closes or opens to a different positions and makes the noise. Artic mentioned the GM eng packed the actuator with grease and that may provide a fix but it didn't for his. This tells me the grease would act like a buffer and provide more resistance for the baffle valve to osilate or chatter. This grease is packed in the actuator side of the valve not on the actual damper as U might guess. Dealer said they couldn't do anything until a recall was issued by GM and the more complaints they had would speed the process up. I can buy that meaning why replace a bad exhaust system with another bad system. SO GUYS WE ARE UP TO 122 HITS ON THIS POST AND I KNOW SOME ARE JUST ME AND OTHERS SHARING BUT ANYONE WITH THIS NOISE ON THIS POST NEEDS TO CONTACT THE CUSTOMER SERVICE FOLKS AND GENERATE A TICKET AND TAKE THEIR CAR IN SO YOUR DEALER CAN GENERATE A TICKET FROM THEIR END AND THIS WILL HELP GM COME UP WITH A FIX OTHERWISE THEY WILL NOT DO ANYTHING IF ONLY A HANDFUL OF GUYS COMPLAIN SO PLEASE FOLLOW UP ON THIS. ALL IT TAKES AN EMAIL TO CUSTOMER SUPPORT OR JUST TAKE YOUR CAR INTO THE DEALER AND GET ON RECORD AND MENTION THE FORUM POST. Sorry for the long post but I wanted all to know where we are on this issue. Remember there is strength in numbers and the squeaking wheel gets the grease. Keep us posted on any activity you have. I am going to bug customer support and my dealer every so often so they know I am not going away. I didn't pay 60K Plus to hear this noise on my vette. Good luck

Ed Ramberger

Hi Richard. I did receive a case number in PM. I am taking the strategy of waiting and seeing. I have several PDR recordings but was never asked to supply them.

Ed

TheMidnightNarwhal

Oh my god... every day I see new problems on the C7. Should I consider this car or not...? The car is perfect and then I read thread like these.

OnPoint

If this bothers you, just go with the M7 transmission. It only goes into V4 mode when you affirmatively tell it to, so would be easy to avoid this.

IBuyGuyToys

Purchased 2016 stingray in Dec. 2015. on way home had a Whoop, Whoop, Whoop noise, about 2/per second @ about 1500 rpm. Any gear 4V 8V or any mode. noise came from back of car, yet this noise, which sounds like a drive train rotational noise is consistent with a noise from the input to the tranny (based on timing and speed). always @ 1500 rpm doesn't matter road speed or gearing. What do You folks recommend, is this the same thing you folks are discussing here?
took car to dealer and we spent a lot of time looking a stuff on lift and driving, which they where eager to do, but didn't find anything. I'm scheduled to drive a demo unit to see if it makes same sound or not.
not worried about it , but a $70k car shouldn't be like this.

TheMidnightNarwhal

If this is due to going from V8 to V4 then that is not a problem. Someone on here showed me a neat little OBDII reader thing you can plug that removes that going automatically and anyways staying in manual mode won't allow it.

So this is 100% caused by switching of V8 to V4? If so, I can scratch this con of my list

OnPoint

Yeah, that's the Range module you're referring to for the automatic to keep in V8 mode. Those work well.

And yes, these issues are associated with the AFM exhaust valves that actuate then going into/out of V4 mode.

Strake

Your situation sounds like several of us are having..... It seems tied to 1500 RPM, regardless of gear, driving mode, V4 or V8, Exhaust setting.

TheMidnightNarwhal

Ok thanks.

AFM or NPP? I just learned NPP is the sports exhaust. What is the AFM?

Strake

Thank you for the update !!!

So the only thing I'm a bit confused about is the "pulling the fuse #32"....

If I am hearing the noise in BOTH V4 and V8 modes, is there any point in me trying to pull the fuse? Now, I can hear the WARBLE noise when the car is in Automatic and switching from V4 to V8. I can also hear the noise when I'm in paddle shift Manual. Would I gain info from still pulling the fuse to keep it in V8 mode...... assuming that is what it does? I already KNOW the car makes the noise in V8 mode.

OnPoint

On the Stingray, there are two sets of valves in the exhaust for cars with the performance exhaust (NPP). The NPP valves are the ones at the back end of the exhaust system that modulate sound b/n quiet and loud. Those valves are robust and trouble-free - and easy to get to in order to clean etc even if they do act up. The AFM (active fuel management) exhaust valves are further upstream on the exhaust and they activate when the engine goes from V8 to V4 operation to keep the exhaust from sounding weird in V4 mode.

The Z06s don't have these AFM exhaust valves. All Stingrays have them (and I presume the GS will too). Most are trouble-free, but some folks have experience these weird noises caused by the AFM valves, mostly A8 cars, as the M7 crowd doesn't use eco mode (which is the only way those cars go into V4 mode) as often as the A8 guys see V4 mode activated.

TheMidnightNarwhal

Ok got it thanks!

I will also opt for the NPP Exhaust.

bjones7131

Fuse 32 powers the AFM valves, pull it and the valves fail open and you would think the noise would go away but i don't think so. Want take but 10 seconds to pull, take a ride and see if it makes a difference.

bjones7131

Ed make an appt. And take it in so they can document it and give their feedback to gm

Strake

I'm assuming that if it IS an AFM valve issue, that doesn't involve tearing the whole rear end of the car apart???

Strake

BJONES....... So what's next for you? Are they ordering a new set of AFM Valves for your car?

bjones7131

It is just another check that only takes 10 seconds to do and it may eliminate your noise or not. I don't think it is a 100% true test, just my opinion.

bjones7131

Dealer says to wait until GM does a recall on the valves. Only way to get them to do a recall is to get as many as possible to complain, take your car into your dealer and let them check it and they will do the follow up with GM and hopefully if enough complain they will do a recall.

Ed Ramberger

I did take it in. They added additive to the differential. Tech couldn't explain how that could help and I asked how clutches would make noise in a straight line at a specific RPM in different gears as the diff is on the output side. I let them do it but doubted it was going to help - but gotta let them try. Nice guys, but it was difficult to even get the noise properly documented. They just haven't heard it at my dealership - I'm the lucky first guy.

Same noise and they want me to keep driving it. One thing I did notice. They had the car jacked up by the rear before it went up on the rack. I thought the warble noise changed immediately upon leaving, but I heard it again tonight. I swear something shifted and it's severity changed slightly - after it was jacked by the floor jack. I'm tuned into it now and can tell you when it's changing tone. Tonight it was pretty loud again. Both noises are still there. The growl at 1000 and the warble around 1500. I was initially wondering if something shifted when they jacked it up - I did not see what crossmember or where they jacked it on but it was a center point.

I also wonder what the effect will be as the exhaust gets mileage and some carbon in it as well as a little more throttle. Perhaps that will quiet things down - only the shadow knows. Either way, It's been frustrating, but at this point I am going to enjoy the car and let the warranty take care of it when the fix comes out.

Every morning when I back out, I hear a quick growl (sounds like exhaust) as it passes 1,000. When I get stuck in slow traffic and the trans stays in 3rd and we're creeping I hear it. I can duplicate it by being in 1st, and applying brake and moving forward at 1,000 rpm. Sounds like it comes from rear right. Odd thing is the car MUST be moving for it to growl.

Dealer is trying - I think this is beyond all of our dealer's ability to diagnose and prove out the diagnosis because I believe it's in a component they don't just have laying around to swap out. I believe firmly that someone at GM knows what we are talking about and we need to find that person.

I truly feel for the guys who have had driveline components replaced only to keep hearing it. I'm not going down that road. If you follow the Camaro forums, those guys have had massive complaints about active exhaust noise for several years.

I started finding myself turning down the radio and capturing recordings - that's taking the fun away from the car. I just want to enjoy it so as I've gotten several recordings and it's documented, I need to just drive it.