[ev_santillano]

Im driving a 2017 1SS automatic. On my way home from work I hit the gas to start merging onto the freeway and as hit the pedal I heard what I can only describe as a valve flap opening very loudly and suddenly. It did not sound normal it was much louder than anything I have heard. So Im thinking it was the AFM valve that opened by me hitting the gas and the car going from V4 to V8 mode but after that I started to notice what I'm thinking is an exhaust leak coming from somewhere along the exhaust pipping on the drivers side towards the front of the car but behind the engine which further leads me to believe something happened down there when the AFM flap opened up. It sounds exactly like an exhaust leak and it started happening after the loud valve opening sound I described. Anyone have any ideas? Ive only been under the car once to change the oil and I don't really remember how everything looks under there. She is definitely going up on a lift tomorrow when I get to work so I can check it out.

[ev_santillano]

So I put the car up on a lift and realized that the AFM flaps are not where I thought they were. I listened around for an exhaust leak but found nothing and I couldn't feel any air leaking from where I was hearing the noise. I have only been able to replicate it while accelerating slightly on the freeway. I'll be cruising at around 70, slightly hit the gas, and I can hear what sounds more of rattling from the same area (around the cats) while the car is accelerating. It happens around town at times but only while accelerating Any ideas? Something in the cats? haha I don't want to let this thread die just yet.

[Slem]

Originally Posted by ev_santillano

Im driving a 2017 1SS automatic. On my way home from work I hit the gas to start merging onto the freeway and as hit the pedal I heard what I can only describe as a valve flap opening very loudly and suddenly. It did not sound normal it was much louder than anything I have heard. So Im thinking it was the AFM valve that opened by me hitting the gas and the car going from V4 to V8 mode but after that I started to notice what I'm thinking is an exhaust leak coming from somewhere along the exhaust pipping on the drivers side towards the front of the car but behind the engine which further leads me to believe something happened down there when the AFM flap opened up. It sounds exactly like an exhaust leak and it started happening after the loud valve opening sound I described. Anyone have any ideas? Ive only been under the car once to change the oil and I don't really remember how everything looks under there. She is definitely going up on a lift tomorrow when I get to work so I can check it out.

The flap noise you are hearing I also hear on mine and I now have a rattle or exhaust leak in the location you described after letting the dealer do the trans oil line recall. Eventually I will be purchasing ramps and look over everything and hopefully find the cause.

[Elbert_AK1989]

It's happening to my car too, a hissing noise after 3k rpm at 3rd gear. I also just got my trans recall done. 2016 SS w a8