[MatijaP]

Hello good people of the Camaro community.

I have bought a used 2019 2SS Camaro on Saturday (a week ago) - Im in Germany and the car was an US import.
After some pulls on the highway the AFM/(DOD?) valve (the one in front of the rear tire axle, not the NPP) on the RH started banging very loudly (as if one would take a wrench and bang on a steel tube) in same frequency and steady rhythm. This happens when the car goes into V4 mode and stays for some time (until its back to V8?).
I took it to a service workshop and they told me the valve on the RH is broken, so they are now waiting for offer from GM for the parts - can this part be replaced separately or does it come with a part of exhaust?
The connector for the AFM valves on right is now disconnected so it doesn't bang while I'm driving, and I disconnected also the left to have the same state in both tubes...

Since I'm in Germany and the part will probably have to come from the US, it will take some time until I get it fixed. So the questions are:
- I guess the default valve position is open, so there should be no problem in driving the car normally? Even when the car goes into V4 mode and the AFM valves are open, or does this do any damage to the engine (I noticed today that I'm mostly in V4 mode due to cruising on highway)?
- I am going home in 3 weeks and one-way trip is some 850 km (530 miles) - is this safe with this sort of issue (valves being open while in V4 mode)? the CEL is always on, but I know its because the connector being disconnected
- I like the fuel economy due to V4, so I wouldn't disable the AFM just yet - since the price of fuel in Germany is quite high its about 7,2 USD/gallon

- or do you maybe know some shops in Europe where I could get the part faster/easier than shipping it from the US and waiting for it? - or someone (from Europe) that has removed his which I could buy and put into mine

I read the forum looking for these answers, and for similar issue, but couldn't find anyone having broken AFM valves/such banging noise on the internet (maybe they are not called AFM valves?). People mostly talk about deleting AFM and disabling V4, so I couldn't find this specific issue (or didn't look hard enough?).

TLDR - AFM valves are always open due to issue;
- can I drive with AFM valves open (connector disconnected) in V4 mode or does this damage the engine?
- can I go on a trip which is 850km (530 miles) in one-way - is it safe in V4 mode with valves open?
- do you know any shops where AFM valve part could be bought with low waiting time? - or someone from Europe that has removed theirs which I could buy.

[cmitchell17]

Originally Posted by MatijaP

Hello good people of the Camaro community.

I have bought a used 2019 2SS Camaro on Saturday (a week ago) - Im in Germany and the car was an US import.
After some pulls on the highway the AFM/(DOD?) valve (the one in front of the rear tire axle, not the NPP) on the RH started banging very loudly (as if one would take a wrench and bang on a steel tube) in same frequency and steady rhythm. This happens when the car goes into V4 mode and stays for some time (until its back to V8?).
I took it to a service workshop and they told me the valve on the RH is broken, so they are now waiting for offer from GM for the parts - can this part be replaced separately or does it come with a part of exhaust?
The connector for the AFM valves on right is now disconnected so it doesn't bang while I'm driving, and I disconnected also the left to have the same state in both tubes...

Since I'm in Germany and the part will probably have to come from the US, it will take some time until I get it fixed. So the questions are:
- I guess the default valve position is open, so there should be no problem in driving the car normally? Even when the car goes into V4 mode and the AFM valves are open, or does this do any damage to the engine (I noticed today that I'm mostly in V4 mode due to cruising on highway)?
- I am going home in 3 weeks and one-way trip is some 850 km (530 miles) - is this safe with this sort of issue (valves being open while in V4 mode)? the CEL is always on, but I know its because the connector being disconnected
- I like the fuel economy due to V4, so I wouldn't disable the AFM just yet - since the price of fuel in Germany is quite high its about 7,2 USD/gallon

- or do you maybe know some shops in Europe where I could get the part faster/easier than shipping it from the US and waiting for it? - or someone (from Europe) that has removed his which I could buy and put into mine

I read the forum looking for these answers, and for similar issue, but couldn't find anyone having broken AFM valves/such banging noise on the internet (maybe they are not called AFM valves?). People mostly talk about deleting AFM and disabling V4, so I couldn't find this specific issue (or didn't look hard enough?).

TLDR - AFM valves are always open due to issue;
- can I drive with AFM valves open (connector disconnected) in V4 mode or does this damage the engine?
- can I go on a trip which is 850km (530 miles) in one-way - is it safe in V4 mode with valves open?
- do you know any shops where AFM valve part could be bought with low waiting time? - or someone from Europe that has removed theirs which I could buy.

The valves are welded to the exhaust pipe, but the actual actuator is removable. If you can get under it and swap them from side to side or either put the rear one on and see if it does the same thing.

It will be fine to drive with them disconnected or open though.

I have some I can send you but I'm in the US. I guess they will let that through customs?

You can drive as long as you want to with them open or not working.

I've never heard of this happening, I am pretty sure the signal that drives the valves is on a LIN bus which means it's not a analogue signal, so it's even more unlikely it would be getting a bad signal that would cause it to open and close really fast like that. If you can swap one and it works normal that will tell you it's the actuator.

[cam765]

Wow, very interesting. I too have never heard of this before. Usually if the AFM valve actuators get stuck in the open or closed position, you will quickly get a check engine light but otherwise it may not be that noticeable that anything is wrong (besides the exhaust note). But this is the first I have heard where there is an accompanying loud banging noise. I wonder if it is the valve itself inside of the exhaust that is damaged.

Many people disconnect their AFM actuators (but leave them plugged in and zip tied out of the way under the car, or go the AWE AFM valve simulator route to avoid a check engine light). I would say this has been fairly well proven to have no adverse affects on the car. I would feel comfortable driving the vehicle if I were you.

[MatijaP]

Thank you for the answers,

I will call the workshop again tomorrow to confirm if its the valve itself broken or the actuator. So the actuator is easy fix (just put a new one on), but the valve itself requires a bit more work since that section of the exhaust has to be replaced?

I might then also try fitting the NPP actuator on the front (if they are the same?) and see what happens. Also need to fix the NPP rattle so have to get them off anyway.

Now I feel better going on that trip Just wanted to know if I could give it some fun while driving, and not just crusing because of the valves.

[cam765]

Yes, the actuator only is an easy fix, but replacing the valve would certainly be more challenging. Without checking, I would guess the GM service procedure says to replace the entire exhaust in the event of a valve failure. In practicality, especially if you're in a region where it is difficult or expensive to get OEM parts, sectioning that portion of the exhaust with a replacement section would probably make most sense. Or remove the actuators completely and go the AFM delete route

And yes, the NPP and AFM valve actuators are all interchangeable. So you could try swapping to see what that does.

[MatijaP]

If anyone will be searching for the same issue - the RH AFM actuator was broken (when I removed it, you could freely rotate the spindle until it went back into place).

So, thanks @cam765 for recommending to switch the valves. I now installed the NPP actuator to the front, and pulled the NPP fuse