[WorthFlorida]

After all these weeks this morning I checked out what is going on. I left the vehicle setting in Stealth Mode overnight and the mode set in Touring. Laying on the ground looking inside the outer pipe, the butterfly's were wide open. Without touching the brake pedal I pushed the start button to light up the vehicle. I did not hold it in for the 5 seconds. The butterflies remain open. With the remote I started it and the butterfly's immediately closed but I still got a buzz noise for a few seconds after startup and the exhaust. After the buzz noise stopped the exhaust did quite down more, probably due to the start up fuel mixture program. It might be the butterfly assemble about half way down exhaust pipe. The buzz noise does not sound like it is coming from the outer exhaust pipe butterfly's. It only does it with a cold exhaust, I don't see it as a problem and I'll mention it to the dealer on my next oil change. There is a TSB for the 2015 or 2016 Gen 6 models where the butterfly's would vibrate and the TSB fix is essentially gluing the butterfly to the shaft.

While idling and going from touring to sport or track mode the butterflies go to wide open position. If the mode setting is in track or sport, the butterflies are wide open on start.

LOL on this post, thanks for everyones input.

[ember1205]

Originally Posted by WorthFlorida

After all these weeks this morning I checked out what is going on. I left the vehicle setting in Stealth Mode overnight and the mode set in Touring. Laying on the ground looking inside the outer pipe, the butterfly's were wide open. Without touching the brake pedal I pushed the start button to light up the vehicle. I did not hold it in for the 5 seconds. The butterflies remain open. With the remote I started it and the butterfly's immediately closed but I still got a buzz noise for a few seconds after startup and the exhaust. After the buzz noise stopped the exhaust did quite down more, probably due to the start up fuel mixture program. It might be the butterfly assemble about half way down exhaust pipe. The buzz noise does not sound like it is coming from the outer exhaust pipe butterfly's. It only does it with a cold exhaust, I don't see it as a problem and I'll mention it to the dealer on my next oil change. There is a TSB for the 2015 or 2016 Gen 6 models where the butterfly's would vibrate and the TSB fix is essentially gluing the butterfly to the shaft.

While idling and going from touring to sport or track mode the butterflies go to wide open position. If the mode setting is in track or sport, the butterflies are wide open on start.

LOL on this post, thanks for everyones input.

WRT hearing a noise not coming from the tailpipes...

If your car is an automatic, there are additional actuators further forward, right behind the secondary cat. These will close when the car drops into 4 cylinder mode to maintain back pressure for the engine.

These are the same exact part as the ones on the exhaust tips, and it's conceivable that they could suffer the same "rattle" that the ones on the tips can encounter (that had a TSB to repair them with epoxy). Might be worth a closer look.

As far as the valves being open on start, even in stealth mode goes, I don't know if that's how it should be. Try setting the car to stealth mode, ensuring that all is as quiet as it's going to be, then get out and look at the valves while the car is running. Turn it off. Check again and see if they flipped open once the car is off.