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Hi, a technical question - I'm planning to buy a second hand NPP axle-back for my non-NPP C7. I understand I will not be able to control the valves and that is ok. There is some choice on eBay, but I'm puzzled as some do include what I understand to be the component that controls the valves and some don't. Example is attached photo where the black plastic thing is missing. Why was it removed / is it safe to buy this and install? Thanks!
I can confirm that the missing piece is the actuator which opens the valve on the NPP system. Why it was removed... I have no idea, maybe they sold it separately? The default position of the valve is open. This is why people remove the control fuse - no power = no closing = loud all the time. Thus I assume no actuator at all would give the same results. My only worry would be if the actuator contains some spring that keeps the valve from flapping around. Worse case you need to rig something to ensure the valve stays open and doesn’t rattle.
If you buy an NPP system for a Stingray make sure it has the values upstream from the muffler. If it doesn't perhaps you can just remove the controllers off of your system and zip tie them someplace on the car. But the computer looks for them and will code w/o them being present.
If you buy an NPP system for a Stingray make sure it has the values upstream from the muffler. If it doesn't perhaps you can just remove the controllers off of your system and zip tie them someplace on the car. But the computer looks for them and will code w/o them being present.
I think that is only for the Auto cars, the Manual Corvettes dont have the upstream AFM controllers.
My 19 base Stingray w/ M7 has the valves ahead of the muffler.
That would be correct.
It is confusing since GM originally had the AFM valves on all C7s, (except the Z06 & ZR1).
Around the 2017 model year, I think, GM removed the AFM valves from the manual transmission Z51 and GS C7s. Base C7s, regardless of transmission, kept the AFM valves.
There may be other changes too, sometimes I am confused on which C7s have AFM valves.
I can confirm that the missing piece is the actuator which opens the valve on the NPP system. Why it was removed... I have no idea, maybe they sold it separately? The default position of the valve is open. This is why people remove the control fuse - no power = no closing = loud all the time. Thus I assume no actuator at all would give the same results. My only worry would be if the actuator contains some spring that keeps the valve from flapping around. Worse case you need to rig something to ensure the valve stays open and doesn’t rattle.
The "spring" is attached to the muffler valve to hold it open. The actuator motor provides the power to overcome the spring pressure and close the valve, not the other way around.
NPP exhaust question
