Rattle in V4 mode
Thread Starter
Instructor
Joined: Nov 2008
Posts: 170
Likes: 9
From: Maryland
Rattle in V4 mode
So I have done some searching and reading through the forums - what I'm having doesn't seem the be the normal DI "tick". And the other threads that might be having the same thing didn't seem to have a definitive cause - people where going to take their cars in and the threads then trailed off.
So when the car is in 4 cylinder mode she will have this rattle coming from up front (can't tell engine or exhaust) about half the time. It doesn't happen when she is switching into or out of 4 cylinder mode and it doesn't happen in 8 cylinder mode. It's not all the time in 4 cylinder mode either but consist enough and getting louder that I'll be calling them to schedule the appointment to bring it in next week. I'm just hoping some people here have some ideas before I deal with the dealership.
I captured a video with the pdr where you can hear it.
So you don't have to watch the entire video - you can hear it at the following points:
3:37-3:40
5:31-5:35
6:54
7:33-7:36
10:40-10:48
10:55-10:57
11:05-10:07
11:45-12:10
14:19-14:21
(car is 2015 z51 automatic)
So when the car is in 4 cylinder mode she will have this rattle coming from up front (can't tell engine or exhaust) about half the time. It doesn't happen when she is switching into or out of 4 cylinder mode and it doesn't happen in 8 cylinder mode. It's not all the time in 4 cylinder mode either but consist enough and getting louder that I'll be calling them to schedule the appointment to bring it in next week. I'm just hoping some people here have some ideas before I deal with the dealership.
I captured a video with the pdr where you can hear it.
So you don't have to watch the entire video - you can hear it at the following points:
3:37-3:40
5:31-5:35
6:54
7:33-7:36
10:40-10:48
10:55-10:57
11:05-10:07
11:45-12:10
14:19-14:21
(car is 2015 z51 automatic)
Last edited by Kenafin; Apr 23, 2017 at 02:05 PM.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Very hard to hear but I do hear something-----REMEMBER when running in 4 cyl mode there are a set of butterfly valves in the exhaust pipes that almost completely close to eliminate the exhaust drone while running on 4 cyl-----These butterfly exhaust valves tend to chatter on occasion opening and closing rapidly which will create a metallic sound---
When I 1st got my C7 the valves were actually stuck closed all the time---on 4 cyl--I had to take the car immediately back to the dealer and they told me the were just "new" and sticking" Who knows what the real cause was-----
Most C7 owners wil simply have a tuner turn OFF the AFM system and be done with all the AFM issues---My mileage did not suffer much at all when I turned the AFM off---It's a sports/muscle car----not a Prieous------------
When I 1st got my C7 the valves were actually stuck closed all the time---on 4 cyl--I had to take the car immediately back to the dealer and they told me the were just "new" and sticking" Who knows what the real cause was-----
Most C7 owners wil simply have a tuner turn OFF the AFM system and be done with all the AFM issues---My mileage did not suffer much at all when I turned the AFM off---It's a sports/muscle car----not a Prieous------------
Intermediate
Joined: Apr 2017
Posts: 33
Likes: 16
From: TX
I had that noise and it ended up being the idler pulley! Dealer replaced it problem gone..it drove me crazy because everytime it was in V8 mode it would not do it. I even installed a AFM disable on my car to get rid of the noise. However when i got time i took it in.
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
There was a problem with quite a few of the 2014 production year models where the damping fluid in the belt tensioner leaked out creating a noise particularly evident during V4 mode. The tensioner still functioned but was noisy because of the lost damping fluid which allowed it to rattle. I thought the issue was addressed during model year 2014 however even with a revised design some parts just fail so that could be the issue with your 2015. As suggested above the AFM sound control valves in the exhaust system could also be the issue.
Advanced
Joined: May 2018
Posts: 78
Likes: 15
From: Roseville Ca.
v4 rattle
So I have done some searching and reading through the forums - what I'm having doesn't seem the be the normal DI "tick". And the other threads that might be having the same thing didn't seem to have a definitive cause - people where going to take their cars in and the threads then trailed off.
So when the car is in 4 cylinder mode she will have this rattle coming from up front (can't tell engine or exhaust) about half the time. It happens when she is switching into or out of 4 cylinder mode and it doesn't happen in 8 cylinder mode or manual . I'll be calling dealer to schedule the appointment to bring it in next week. I'm just hoping some people here have some ideas before I deal with the dealership.
I captured a video with the pdr where you can hear it. https://www.youtube.com/watch?v=YWCkI-Yl5E4
So you don't have to watch the entire video - you can hear it at the following points:
3:37-3:40
5:31-5:35
6:54
7:33-7:36
10:40-10:48
10:55-10:57
11:05-10:07
11:45-12:10
14:19-14:21
(car is 2015 z51 automatic)
So when the car is in 4 cylinder mode she will have this rattle coming from up front (can't tell engine or exhaust) about half the time. It happens when she is switching into or out of 4 cylinder mode and it doesn't happen in 8 cylinder mode or manual . I'll be calling dealer to schedule the appointment to bring it in next week. I'm just hoping some people here have some ideas before I deal with the dealership.
I captured a video with the pdr where you can hear it. https://www.youtube.com/watch?v=YWCkI-Yl5E4
So you don't have to watch the entire video - you can hear it at the following points:
3:37-3:40
5:31-5:35
6:54
7:33-7:36
10:40-10:48
10:55-10:57
11:05-10:07
11:45-12:10
14:19-14:21
(car is 2015 z51 automatic)
Last edited by Rich0071; Oct 27, 2018 at 04:56 PM. Reason: Error in a statement.
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3rd Gear
Joined: Dec 2018
Posts: 3
Likes: 3
Does it sound like the noise is coming from the dashboard?
I have a 2014 vette and I have an annoying rattle.
It sounds like it is coming from the passenger dashboard area.
I thought it might be a speaker shaking or something like that.
Thank you if you have a chance to respond.
I have a 2014 vette and I have an annoying rattle.
It sounds like it is coming from the passenger dashboard area.
I thought it might be a speaker shaking or something like that.
Thank you if you have a chance to respond.
Last edited by 2lazy2type; Dec 15, 2018 at 04:35 PM.
Advanced
Joined: May 2018
Posts: 78
Likes: 15
From: Roseville Ca.
With the windows up it sounds like it's coming from the dash. With windows down it sounds like it's coming from the drivers side body. Really can't tell exactly where the nose is coming from. If it's a harmonic issue noise can be created from one area and cause noises elsewhere. My noise is back. Went back to the dealer. They are scratching their heads. and "researching".
Waiting over a month to hear back from them.
Waiting over a month to hear back from them.
3rd Gear
Joined: Dec 2018
Posts: 3
Likes: 3
Sorry to hear it
I wonder if we should just accept it at this point.
As a cure i'm thinking to get most of the inside dynomatted. Something like what DSOMonster did.
https://www.corvetteforum.com/forums...amn-place.html
I did notice that I can get the noise to go pretty steady if I put it in manual mode and keep the RPMs low.
As a cure i'm thinking to get most of the inside dynomatted. Something like what DSOMonster did.
https://www.corvetteforum.com/forums...amn-place.html
I did notice that I can get the noise to go pretty steady if I put it in manual mode and keep the RPMs low.
Last edited by 2lazy2type; Dec 16, 2018 at 02:38 AM.
Le Mans Master
Joined: Feb 2010
Posts: 7,798
Likes: 314
From: Santa Fe Tx
I have had this problem since having the oil changed in my 2016 Z51
The noise occurs only in 4V under a slight acc. load. Does not occur in 8V mode period or in 4V mode if car is coasting??
Sound like butterfly valve flutter or as some say belt tensioner???
Does anyone have a GM TSB for this condition?
Thanks
The noise occurs only in 4V under a slight acc. load. Does not occur in 8V mode period or in 4V mode if car is coasting??
Sound like butterfly valve flutter or as some say belt tensioner???
Does anyone have a GM TSB for this condition?
Thanks
Instructor
Joined: Jul 2019
Posts: 168
Likes: 91
I have had this problem since having the oil changed in my 2016 Z51
The noise occurs only in 4V under a slight acc. load. Does not occur in 8V mode period or in 4V mode if car is coasting??
Sound like butterfly valve flutter or as some say belt tensioner???
Does anyone have a GM TSB for this condition?
Thanks
The noise occurs only in 4V under a slight acc. load. Does not occur in 8V mode period or in 4V mode if car is coasting??
Sound like butterfly valve flutter or as some say belt tensioner???
Does anyone have a GM TSB for this condition?
Thanks
Intermediate
Joined: Jan 2020
Posts: 39
Likes: 9
FYI, you can't feel it but the power train sure does, when in V4 mode there is much vibration which has caused numerous front torque shaft bearings to fail. If the dealership can't figure out the noise issue, mention the torque tube front bearing. AFM is horrible for our cars. Its just a marketing scam by GM. Have it disable ASAP. Either with a AFM range delete or a tune.
Last edited by howe2011; Jan 24, 2020 at 06:03 PM.
Advanced
Joined: May 2018
Posts: 78
Likes: 15
From: Roseville Ca.
Same problem, replacing tensioner fixed my rattle. I posted this on another thread. My rattle occurred at 1500 rpm going from V8 to V4. Dealer previously said it was the belt and replaced it for $300.
