AFM & NPP exhaust valves

1supersport · 07-18-2024, 10:52 AM

I've come to realize the squeaking exhaust valves are a common issue on the Camaros. I've owned 2 brand new Camaros, LT1 2021 and my current SS 2023. Both had chirping noises coming from these valves. The issues for BOTH started after a month of owning the cars, not even 1,000 miles on them. I'm reaching 10,000 miles on my current SS and just dealing with the chirping, but it is very annoying.

I have a few questions and potential recommendations for others with the issue.

1. Is there any aftermarket exhaust system that works better than the stock, removing this issue all together?

2. It seems like replacing the exhaust system under warranty with new stock one isn't worth it since many have said the issue returns. Not sure if anyone has had any luck here?

I'll link an image of where the valves are located. Flange set #1 are AFM and flange set #2 are NPP. https://imgur.com/3GjQK8k

There's also TSB #16-NA-003 which I'll attach a link to as well. https://static.nhtsa.gov/odi/tsbs/20...34535-9999.pdf

Very annoying this issue has been ongoing since at least the 2016 models. Seems like an inherent design flaw on GM's end.

Zapote21 · 07-18-2024, 11:05 AM

I use a range device always so the AFM valves are a no issue. Also, did an axle back exhaust so my NPP valves are off to the side and not functional.
But I dont remember any squeaking when I had them operational on any of my Camaros

1supersport · 07-18-2024, 11:10 AM

Quote:

Originally Posted by Zapote21

I use a range device always so the AFM valves are a no issue. Also, did an axle back exhaust so my NPP valves are off to the side and not functional.
But I dont remember any squeaking when I had them operational on any of my Camaros

TSB #16-NA-003 says temperature and humidity related. I am in Florida and noticed others with the issue posting from Florida, but also a few from Cali which I know is a lot dryer.

2SS Capt · 07-18-2024, 11:32 AM

Get a Range AFM Disabler and pull the NPP fuse (NPP valves will remain full open all the time). Easy and cheap fix and easily reversible.

SSShark · 07-18-2024, 11:34 AM

Quote:

Originally Posted by 1supersport

I've come to realize the squeaking exhaust valves are a common issue on the Camaros. I've owned 2 brand new Camaros, LT1 2021 and my current SS 2023. Both had chirping noises coming from these valves. The issues for BOTH started after a month of owning the cars, not even 1,000 miles on them. I'm reaching 10,000 miles on my current SS and just dealing with the chirping, but it is very annoying.

I have a few questions and potential recommendations for others with the issue.

1. Is there any aftermarket exhaust system that works better than the stock, removing this issue all together?

2. It seems like replacing the exhaust system under warranty with new stock one isn't worth it since many have said the issue returns. Not sure if anyone has had any luck here?

I'll link an image of where the valves are located. Flange set #1 are AFM and flange set #2 are NPP. https://imgur.com/3GjQK8k

There's also TSB #16-NA-003 which I'll attach a link to as well. https://static.nhtsa.gov/odi/tsbs/20...34535-9999.pdf

Very annoying this issue has been ongoing since at least the 2016 models. Seems like an inherent design flaw on GM's end.

Easiest solution is to buy the Range AFM disabler. My valves were noisy, but since installing the Range, no noise.

1supersport · 07-18-2024, 11:35 AM

Quote:

Originally Posted by 2SS Capt

Get a Range AFM Disabler and pull the NPP fuse (NPP valves will remain full open all the time). Easy and cheap fix and easily reversible.

How do I make sure valves are open before fuse is pulled? And I heard range devices can trigger CEL. It is common or rare?

RideWithDanger · 07-18-2024, 12:36 PM

Just a heads up for the people saying to just pull the fuse or get a range disabler, my last Camaro had this exact issue and I made a video on it: https://youtu.be/QmqrQ1xk9Ho

But my car had the AFM system tuned out, and no NPP, and still had the rattle. If the AFM valves are the ones rattling, which mine were, then disabling it won't actually do anything because they rattle and squeak in the open position. Maybe some people here have had luck with just disabling it but that was not the case for me. My rattle didn't even start until long after it was tuned out.

You have a few options on what you can do. Option 1. You can disable the AFM system and also remove the valves. A catback will do this, and I highly recommend AWE Touring system if you do this. Option 2. AWE also sells valve simulators so you don't even have to tune out AFM or get a range device, just hook the valves up to the simulators. Option 3. You can weld the AFM valves open if you want to keep your stock exhaust.

SomeGeoffGuy · 07-18-2024, 12:53 PM

The rattle and the squeak are two different issues! My 2016 had both. My 2023 has neither (so far!). The dealer had some different repairs for the rattle - some with epoxy and the one where you trim the ears off the gear assembly.

-Geoff

2SS Capt · 07-19-2024, 01:06 AM

Quote:

Originally Posted by 1supersport

How do I make sure valves are open before fuse is pulled? And I heard range devices can trigger CEL. It is common or rare?

No CEL on the Range, the valves are spring loaded to the open position, so no power, they are open, pull the fuse, they stay open... My fuse has been pulled for 2+ years along with a Range device even longer than that...

gkitab241 · 10-17-2024, 07:03 PM

I'm new to the forums so excuse me if I'm doing this wrong. Lol.

So I have done new cat back and afm valves on my 23 ss are in the trunk. Found it leads to cel. Clear the code but it comes back on start up. Plug valves in and ECU is satisfied. I know they can be tied up and know the have the simulators then will keep them mounted up and away. I have heard that the vettes have dummy plugs which are a nice option to satisfy. But haven't been able to find the for Camaro.

Does anyone know of any or if the vette afm/npp dummy plugs module will work?

07-18-2024, 11:32 AM	#4
2SS Capt 2020 Shadow Gray 2SS Drives: 2020 2SS - A10, NPP, MRC, CAI Join Date: Dec 2019 Location: SoCal Posts: 3,756	Get a Range AFM Disabler and pull the NPP fuse (NPP valves will remain full open all the time). Easy and cheap fix and easily reversible. __________________ 2020 SGM 2SS - A10, NPP, MRC, Red Calipers, Black Fender Badge, Footwell Lighting *After delivery:* - GMP CAI, GMP Black Strut Tower Brace, MRR017 1LE Wheels, SS Armrest, Black Fuel Door, Stainless Pedals, SS Wheel Caps, GM Splash Guards, DD Smoked LED Markers, Smoked Rear Reflectors, Mishimoto Catch Can, Xpel PPF-Full Front & Rockers, 35% Tint, CeramicPro coated, RST Stainless Brake Lines, Castrol SRF, MSD Plug Wires, Mamo V3 Ported TB *Left: My "fun" ride (455 HP). Right: My "work" ride (52,000 HP): a Gulfstream G600. One's top speed is 180 Mph, the other, 620 Mph. BOTH AWESOME to operate...*

07-18-2024, 12:36 PM	#7
RideWithDanger Drives: 23 2SS 1LE Join Date: Feb 2019 Location: GA Posts: 624	Just a heads up for the people saying to just pull the fuse or get a range disabler, my last Camaro had this exact issue and I made a video on it: https://youtu.be/QmqrQ1xk9Ho But my car had the AFM system tuned out, and no NPP, and still had the rattle. If the AFM valves are the ones rattling, which mine were, then disabling it won't actually do anything because they rattle and squeak in the open position. Maybe some people here have had luck with just disabling it but that was not the case for me. My rattle didn't even start until long after it was tuned out. You have a few options on what you can do. Option 1. You can disable the AFM system and also remove the valves. A catback will do this, and I highly recommend AWE Touring system if you do this. Option 2. AWE also sells valve simulators so you don't even have to tune out AFM or get a range device, just hook the valves up to the simulators. Option 3. You can weld the AFM valves open if you want to keep your stock exhaust. __________________ Instagram: RideWithDanger Current Mods: Rotofab, Ported LT2 intake, LT5 TB, Kooks Headers, AWE Touring Catback Radiant Red 23' 2SS 1LE 1100: 11/14/22 \| BUILT: 3/16/23 2000: 2/17/23 \| 4200: 5/8/23 3000: 2/27/23 \| 5000/6000: 5/15/23

07-18-2024, 12:53 PM	#8
SomeGeoffGuy Drives: 2023 2SS Convertible Join Date: May 2009 Location: Metro Detroit Posts: 1,197	The rattle and the squeak are two different issues! My 2016 had both. My 2023 has neither (so far!). The dealer had some different repairs for the rattle - some with epoxy and the one where you trim the ears off the gear assembly. -Geoff __________________ '12 2SS RS Convertible - Traded in. '16 2SS Convertible - White on white, mag-ride, NPP, nav. Sold! '23 2SS Convertible -Same as above except orange.

07-18-2024, 10:52 AM	#1
1supersport Drives: 2023 Camaro 1SS Join Date: Apr 2023 Location: Florida Posts: 56	AFM & NPP exhaust valves I've come to realize the squeaking exhaust valves are a common issue on the Camaros. I've owned 2 brand new Camaros, LT1 2021 and my current SS 2023. Both had chirping noises coming from these valves. The issues for BOTH started after a month of owning the cars, not even 1,000 miles on them. I'm reaching 10,000 miles on my current SS and just dealing with the chirping, but it is very annoying. I have a few questions and potential recommendations for others with the issue. 1. Is there any aftermarket exhaust system that works better than the stock, removing this issue all together? 2. It seems like replacing the exhaust system under warranty with new stock one isn't worth it since many have said the issue returns. Not sure if anyone has had any luck here? I'll link an image of where the valves are located. Flange set #1 are AFM and flange set #2 are NPP. https://imgur.com/3GjQK8k There's also TSB #16-NA-003 which I'll attach a link to as well. https://static.nhtsa.gov/odi/tsbs/20...34535-9999.pdf Very annoying this issue has been ongoing since at least the 2016 models. Seems like an inherent design flaw on GM's end.

07-18-2024, 11:05 AM	#2
Zapote21 Tampa Bay Camaros Drives: 2017 Krypton Green 2SS Join Date: Jul 2011 Location: Westfield, IN Posts: 1,042 View My Garage	I use a range device always so the AFM valves are a no issue. Also, did an axle back exhaust so my NPP valves are off to the side and not functional. But I dont remember any squeaking when I had them operational on any of my Camaros __________________ Me and wife, in order 2011 2SS SGM 2013 2SS Hot wheels vert 2016 C7 DSOM 2012 2SS yellow vert 2017 2LT Krypton Green 2018 2LT Hot wheels crush 2020 2SS Shock vert. 2017 2SS Krypton Green coupe

10-17-2024, 07:03 PM	#10
gkitab241 Drives: 2023 Camaro SS2 Join Date: Sep 2023 Location: Pennsylvania Posts: 8	I'm new to the forums so excuse me if I'm doing this wrong. Lol. So I have done new cat back and afm valves on my 23 ss are in the trunk. Found it leads to cel. Clear the code but it comes back on start up. Plug valves in and ECU is satisfied. I know they can be tied up and know the have the simulators then will keep them mounted up and away. I have heard that the vettes have dummy plugs which are a nice option to satisfy. But haven't been able to find the for Camaro. Does anyone know of any or if the vette afm/npp dummy plugs module will work?

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