[Ox45]

Car: 2020 LT1 A10 NON - NPP Exhaust Convertible ~1K miles.



Symptom: After a cold start when the AFM changes from V4 to V8 I can hear a phoosh type sound. Almost like a BOV. The sound is fairly centered in the car. Maybe right under the passengers seat? This is a vert and the top is down when I hear it, so maybe it isn't too loud... but my wife actually hears it and she typically hears nothing auto related unless the engine has fallen out!


After the car heats up a bit, it seems to go away. I have also noticed the dreaded AFM valve squeak. This is not that... more of a wind rushing type noise. I don't need to be giving it much throttle at all for it to occur, just the change from 4 to 8 cylinders. When it does happen there is no other symptom that I can tell... just the noise.



Is this yet another AFM valve sound, or something else entirely?


Thanks all,
Ox.

[Drags1998]

AFM dosent make ANY noise, I Know I have 2 Cars and 1 Truck with it, Without a recording of the noise its not possible to nail down!!!!

[Doc Oc]

Originally Posted by Ox45

Car: 2020 LT1 A10 NON - NPP Exhaust Convertible ~1K miles.



Symptom: After a cold start when the AFM changes from V4 to V8 I can hear a phoosh type sound. Almost like a BOV. The sound is fairly centered in the car. Maybe right under the passengers seat? This is a vert and the top is down when I hear it, so maybe it isn't too loud... but my wife actually hears it and she typically hears nothing auto related unless the engine has fallen out!


After the car heats up a bit, it seems to go away. I have also noticed the dreaded AFM valve squeak. This is not that... more of a wind rushing type noise. I don't need to be giving it much throttle at all for it to occur, just the change from 4 to 8 cylinders. When it does happen there is no other symptom that I can tell... just the noise.



Is this yet another AFM valve sound, or something else entirely?


Thanks all,
Ox.

I know the exact sound you're talking about, my car had it too before afm/dod was disabled. It became more noticeable with longtubes and had to go. My guess is it's the exhaust volume suddenly doubling that causes the noise (which is why it got louder with lt's) but not really sure. Almost sounds like the car is sneezing when it happens lol

[slimjim2525]

WOW, this is interesting stuff.

[Ox45]

Originally Posted by slimjim2525

WOW, this is interesting stuff.

Not sure what the point is here. Care to elaborate?

Ox.