Another exhaust question
Thread Starter
It's 5 o'clock Somewhere
Joined: Jan 2013
Posts: 1,996
Likes: 21
From: HOUSTON TEXAS
St Jude Donor '13-'14-'15
Another exhaust question
I need some advice/input. I have a 2016 nonZ06, no NPP M7. I have never been in eco mode so afm means nothing to me. It is my understanding on a M7 thats the only time it works. It is also my understanding that the engine sound management on my dash does nothing since I dont have NPP. Here is the issue. I want the exhaust as loud as I can get it. I am convinced the afm valves are doing whatever they want even in the sport mode I usually drive in. There have been times my exhaust has been so quiet you can barely hear it and other times it sounds normal to me. So...i put on Borla ATAK axle back system. Now when it first fires up on cold start it sounds great but the longer I drive the quieter it gets to the point it is not much louder than stock. Is it possible the afm valves are closing? I know I cant pull the fuse without a cel but could i put spacers and longer bolts on the valves so if they try to adjust they wont make contact with the valve? The computer would not know they are not actually adjusting correct? There is nothing else in the exhaust system that could change the exhaust note other than the afm valves correct?Any help is appreciated.
Thread Starter
It's 5 o'clock Somewhere
Joined: Jan 2013
Posts: 1,996
Likes: 21
From: HOUSTON TEXAS
St Jude Donor '13-'14-'15
Yes I am sure. I now have the Borla Atak axle back on it and it is noticeably quieter when I go from Reverse into first in the morning and the longer I drive the quieter it gets to the point it is not much louder than stock. I am going to get some longer bolts with spacers for the AFM so the actuator does not make contact with the valve. I will let everyone know if that makes a difference.
Burning Brakes
Joined: Jan 2010
Posts: 861
Likes: 71
From: Walnut Creek CA
Yep, i have Borla atack on my GS, eliminated NPP. It is louder when i first start the car, but it gets quieter when driving. Bola attack is not much if at all louder than OEM NPP exhaust when fully open. Im kind a dissapointed..
Last edited by Dado5; May 6, 2019 at 11:19 AM.
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Thread Starter
It's 5 o'clock Somewhere
Joined: Jan 2013
Posts: 1,996
Likes: 21
From: HOUSTON TEXAS
St Jude Donor '13-'14-'15
Here is what I did. I pulled the actuator off (3 8mm bolts on each side) and removed the actuator gear. (One torx screw on each side). Put it back together and it now sounds better with no check engine light.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,944
Likes: 12,359
From: NE South Carolina
Yes, there are AFM valves in the exhaust that sit above the axle.
Here is what I did. I pulled the actuator off (3 8mm bolts on each side) and removed the actuator gear. (One torx screw on each side). Put it back together and it now sounds better with no check engine light.
Here is what I did. I pulled the actuator off (3 8mm bolts on each side) and removed the actuator gear. (One torx screw on each side). Put it back together and it now sounds better with no check engine light.
If yours do anything someone messed with the computer, IMO.
Burning Brakes
Joined: Jan 2019
Posts: 1,101
Likes: 409
From: Lake Placid, FL
Yes, there are AFM valves in the exhaust that sit above the axle.
Here is what I did. I pulled the actuator off (3 8mm bolts on each side) and removed the actuator gear. (One torx screw on each side). Put it back together and it now sounds better with no check engine light.
Here is what I did. I pulled the actuator off (3 8mm bolts on each side) and removed the actuator gear. (One torx screw on each side). Put it back together and it now sounds better with no check engine light.
Safety Car
Joined: Dec 2012
Posts: 3,841
Likes: 1,856
From: St. Louis Metro East IL
I've read that the car starts up rich when cold to get the cats up to temp quickly. That makes the nice loud bark on initial startup. As the cats come up to temp and the air-fuel mixture goes back to normal everything quiets down a bit. This is independent of NPP or AFM.
Ron
Ron
Thread Starter
It's 5 o'clock Somewhere
Joined: Jan 2013
Posts: 1,996
Likes: 21
From: HOUSTON TEXAS
St Jude Donor '13-'14-'15
I understand what you all are saying. This is what I have read as well but the car IS louder. It may be the actuators were working when they should not have been. At any rate my sound issue is fixed and I dont have a check engine light. I never drive in eco but even then I doubt the cel would come on because technically the system is still functioning and since there is no sensor on the flapper I dont see how the computer would know of an issue. But again since I dont drive in eco it is a non issue to me. I am just glad to have sound.
Last edited by 42Chevy; May 7, 2019 at 06:24 PM.
