Exhaust Drone

[agentsmurf]

So I tried plugging the exhaust from the rear muffler with some curtain material, and leaving it in performance mode, no more low frequency drone. Cant believe it made such a difference, how do we extrapolate this into a solution? Apparently it is acting like a J pipe, but the valve is before the muffler, so not to sure what is working here, perhaps the curtain material is absorbing the sound waves.

 

[OldVetteGuy]

So I tried plugging the exhaust from the rear muffler with some curtain material, and leaving it in performance mode, no more low frequency drone. Cant believe it made such a difference, how do we extrapolate this into a solution? Apparently it is acting like a J pipe, but the valve is before the muffler, so not to sure what is working here, perhaps the curtain material is absorbing the sound waves.

How about this

 

[2024White392]

Interesting. My drone zone, and many others is from 1450 to 1950 RPM. Well below your drone zone. Our zone is also typically under deceleration and or very light throttle input in that RPM range. No drone in that range while applying a little more throttle. Makes me believe it’s related to Deceleration Fuel Cut Off, which is a coding issue with ECU.

Canadian 392, the DFCO issue makes sense. Mechanically our jeeps are exactly the same as 23’ and 25’ model years right? So it just leaves coding. Who could re-program these settings for us to just match a 2023 model? Seems entirely doable. What about swapping a 2023 pcm into our jeep? Probably not that easy on the pcm swap but just trying to figure out how we test this one. I would be willing to pay a tuner to do this just on the hunch and possibility of fixing it!

 

[Canadian 392]

Canadian 392, the DFCO issue makes sense. Mechanically our jeeps are exactly the same as 23’ and 25’ model years right? So it just leaves coding. Who could re-program these settings for us to just match a 2023 model? Seems entirely doable. What about swapping a 2023 pcm into our jeep? Probably not that easy on the pcm swap but just trying to figure out how we test this one. I would be willing to pay a tuner to do this just on the hunch and possibility of fixing it!

I think DFCO modifications will likely yield the most probability for success. Changes must have been made for our model year (2024). Likely explains why neither Borla or AWE could figure out why their systems droned so terribly in mine. They are both top shelf exhaust companies but I think coding changes threw a curve ball they were not expecting….

 

[OldVetteGuy]

I just logged into my HPtuners account I thought I would check to see if anyone was working with this. Unfortunately found nothing mentioning DFCO and the 392, perhaps it's called something else.

One other thing if it is a parameter that could be changed it would required an unlocked PCM. Once you do this you can forget about your power-train warranty if you do want this tuned out.

 

[3TV]

Have any of you droners taken your 392 to a custom muffler shop and asked them to build an exhaust that doesn't drone? I'm certain it could be done at a lot less cost than trying two different aftermarket exhaust. Aftermarket exhausts are designed to make noise, because that is what most of their buyers want.

Under the assumption that my 65-year-old ears are not as good as they used to be I took my 30-year-old son, who is a bit of an automotive buff for a ride in my 2026 392 today. I asked him to listen to the exhaust and tell me what he thought, specifically if there was any drone. He was actually impressed with how quiet it was. He said it was surprisingly smooth and quiet, and that it sounded really mellow for a vehicle that is sold as a performance vehicle. So, in my study of somewhat less than 100 people (n=2), 100% of the people in this study say the 2026 392 doesn't have this problem.

Based on memory of my 2022 392 when it was stock I would say the 2026 is definitely quieter, but also significantly deeper toned. In comparison, the 2022 had a little more rasp to it. But that is an old memory because my 2022 has had an AWE exhaust on it since late 2023.

 

[2024White392]

I think DFCO modifications will likely yield the most probability for success. Changes must have been made for our model year (2024). Likely explains why neither Borla or AWE could figure out why their systems droned so terribly in mine. They are both top shelf exhaust companies but I think coding changes threw a curve ball they were not expecting….

Does anyone know a tuner that would be willing to look at this? I would buy a tune, go e85 for the hp and get the drone fixed and let go of the warranty if a tuner could take care of the drone issue!

 

[OldVetteGuy]

Does anyone know a tuner that would be willing to look at this? I would buy a tune, go e85 for the hp and get the drone fixed and let go of the warranty if a tuner could take care of the drone issue!

Most professional tuners use HPTuners or EFI Live for modifying factory tunes, that's not to say there are not others but these are the biggies. I used HPTuners a number of times years ago when I was tuning my 17 LT4 in my ZL1 Camaro which by the way had a select-able exhaust system like the Wrangler currently 392 has. You would not believe the things you change (or really mess up) I had a great deal of experience tweaking GM stuff even then I tread very carefully, it's not for the faint of heart!