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!

 

[Isaiah431]

HI All,
New here....took delivery of my 26 Moab 392 about a week ago and unfortunately I have wicked drone as described in the thread. Decel mostly, 1400-2k. Sometimes it happens momentarily while cruising in that range as well. Just barely touching the throttle stops it immediately. I was so excited to get this and throw a Borla Atak on it (love the sound of a raspy v8). Now I'm wondering how long I'll keep it lol. I did order and already receive the NLJL and will pop that in this weekend to see if it helps. I also popped the rear roll bar trim today and am pulling the ANC mics to see what that might do (though I don't hold out much hope there...this seems isolated from that). I really hope we can get this sorted out so that those of us that love loud v8s can enjoy them without the headache inducing drone. I'll report my findings with the NoLimitz this weekend as well.

Another thought here...I've seen folks say that after adding the Magnaflow Rock Krawler (which eliminates the active exhaust) they have no drone. Something in the valve setup or as mentioned, the programming that works behind it may be causing this?? Would be sad though because it is nice to go quiet at times.

 

[Winston]

HI All,
New here....took delivery of my 26 Moab 392 about a week ago and unfortunately I have wicked drone as described in the thread. Decel mostly, 1400-2k. Sometimes it happens momentarily while cruising in that range as well. Just barely touching the throttle stops it immediately. I was so excited to get this and throw a Borla Atak on it (love the sound of a raspy v8). Now I'm wondering how long I'll keep it lol. I did order and already receive the NLJL and will pop that in this weekend to see if it helps. I also popped the rear roll bar trim today and am pulling the ANC mics to see what that might do (though I don't hold out much hope there...this seems isolated from that). I really hope we can get this sorted out so that those of us that love loud v8s can enjoy them without the headache inducing drone. I'll report my findings with the NoLimitz this weekend as well.

Another thought here...I've seen folks say that after adding the Magnaflow Rock Krawler (which eliminates the active exhaust) they have no drone. Something in the valve setup or as mentioned, the programming that works behind it may be causing this?? Would be sad though because it is nice to go quiet at times.

I wonder if you're also hearing the 4cyl mode kick in too. That's a gross garble sound. Once you got the NoLimitz, that'll turn that off.
Oh, and congrats! Enjoy the hell out of it.

 

[Isaiah431]

I wonder if you're also hearing the 4cyl mode kick in too. That's a gross garble sound. Once you got the NoLimitz, that'll turn that off.
Oh, and congrats! Enjoy the hell out of it.

Might be at times, but at others it's a constant bass drone. I love the cracks and pops. Actually, in off road + it just gets worse. I have seen others say the OR+ doesn't stop MDS though, so I have hope.

 

[Isaiah431]

ugh....pulled everything apart and tried to get the no limitz up and running this weekend to no success. The no limitz unit must be faulty. I installed it correctly, cycled multiple times, removed and reinstalled multiple times....NL never pops up in the dash.

 

[OldVetteGuy]

There's very few things that can be causing the issue.
1. The BCM cannot see the nolimitz on the canbus, (this is the small connector you pluged into the green block and the one you removed plugs into the connector going back to the nolimitz module.
2. If you look at the nomimitz unit and it has no lights on it what so ever and the ignition is in the run condition more then likely it is stuck asleep or bad, unplug the large connector going into in, wait 30 seconds and plug it back in.
Next hold the left arrow and press the vehicle start with your foot off the brake if the hazard light don't flash it probably toast and get an RMA from ZAutomotive, they will promptly replace it.

 

[BarneyM]

ugh....pulled everything apart and tried to get the no limitz up and running this weekend to no success. The no limitz unit must be faulty. I installed it correctly, cycled multiple times, removed and reinstalled multiple times....NL never pops up in the dash.

Silly question but you are on the correct screen to see the NoLimitZ? You have to be on the Audio screen to see it.

 

[Isaiah431]

Thanks for the replies guys! It is lit up and green, and I did this on "run" and the audio screen. The guys at Z got back to me and said plug it into my PC and updated the firmware on it and try again. Will do that in the next few days and hope it works.

 

[Isaiah431]

Victory!!! Got a little time yesterday and got my Nolimitz installed and working. disabled MDS and boom...75% of my drone and unpleasantness is gone! There is still a little boom from the exhaust in certain spots, but it's so in frequent and short lived that I'm not concerned. It was clear very quickly that the MDS being disabled was what I needed. Now I can move on to the MRT H pipe!

 

[Canadian 392]

Victory!!! Got a little time yesterday and got my Nolimitz installed and working. disabled MDS and boom...75% of my drone and unpleasantness is gone! There is still a little boom from the exhaust in certain spots, but it's so in frequent and short lived that I'm not concerned. It was clear very quickly that the MDS being disabled was what I needed. Now I can move on to the MRT H pipe!

Thanks for the update.

Activating the Off Road + button should also prevent MDS from kicking in, at least on the 2024 and later model years. So big a difference with NoLimitz compared to just using Off Road + activated to prevent MDS kicking in?

Makes me wonder if MDS still kicks in below 2000 RPM, even with Off Road+ activated....

 

[Isaiah431]

Off Road + still had lots of unwanted noise for me....it seemed to still go into 4cyl mode. Manual mode was the same. Off Road + still has the most unwanted noise of any and mostly on decel. That seems to now to a "characteristic" of the overall design that has been referenced. We'll see if the mitigating properties of the h pipe help with that and get us a little louder growl.

 

[Rob_R]

2026 Moab - I have a bit more than 500 miles on the Moab. I do not really get drone, but more of a boominess, as some have described, when off the gas and coasting. If I watch the mileage gauge, (which tells me when MDS is active) the boominess is definitely associated with active MDS. With the exhaust in quiet mode, it is a non-issue and somewhat tolerable in loud mode. I will note that as I put miles on the Moab, either the boominess is being reduced or I am just getting used to it.

 

[ag4ever]

I just picked up my Moab and drove about 150 miles home.

The drone is crazy at or under 2,000 rpm when in performance mode.

When in quiet mode, not too bad.

Deceleration is where it is worst.