Exhaust Drone

[Ten4Jeep]

Wanted to share a weird but awesome experience we had with exhaust drone on our JL Rubicon 392.

My son is super sensitive to low-frequency drone – the kind that used to hit around 30-55 mph with the active exhaust in quiet mode. It wasn’t constant, but when it showed up (light throttle, cruising in town or on slower highways), it drove him nuts. Heads-up: it was NOT just happening in 4-cylinder MDS mode – in full V8 quiet mode too.

We decided to pull the factory dual-tone muffler (the big active valve unit) only because I wanted to black it out for looks. purely aesthetic. We wire-brushed the entire thing to bare metal, prepped it, and shot it with Cerakote Glacier Black (C-7600). Looks stealthy as hell now – way cleaner under the Jeep. And mud just falls off.

Here’s the surprise after putting it back on and running about 600 miles (mix of highway, city, and trails), my son says the drone is completely gone. Not reduced – gone. He hasn’t complained once, and he’s the canary in the coal mine.

My theory is heat retention. The ceramic coating acts as a thermal barrier, keeping more heat inside the muffler body and exhaust gases instead of radiating it out quickly. This seems to change how the muffler resonates at those lower speeds, killing the drone frequency we were getting before. Total side benefit we never expected.

The exhaust note is unchanged – still that stock dual-tone personality (quiet when closed, mean when open).

If any of you are fighting drone and don’t want to swap to a full aftermarket system, coating the factory muffler might be worth trying. Cheap experiment if you’ve got access to a air gun, and the blacked-out look is a huge bonus.

That looks much better!!! I love the sound of the OE setup, so I’m probably going to paint mine like you did come spring. Nice job

 

[station378]

You’re definitely not crazy, and you’re not alone. A lot of 2024 owners are reporting the exact same low-frequency boom in that RPM range, especially on decel, and the fact that exhaust swaps and ANC deletes don’t fix it really points to a calibration or exhaust tuning change for ’24. The inconsistency between vehicles makes it feel like a build or revision issue rather than “that’s just how it is.”
I haven’t seen a confirmed fix yet, but a few people have opened cases with Jeep corporate and were told engineering is “aware.” If this is a software or exhaust revision problem, the only real solution is going to come from Jeep, not aftermarket parts. I’d definitely encourage everyone affected to open a case so it gets documented numbers matter if we want a real response.

 

[Canadian 392]

You’re definitely not crazy, and you’re not alone. A lot of 2024 owners are reporting the exact same low-frequency boom in that RPM range, especially on decel, and the fact that exhaust swaps and ANC deletes don’t fix it really points to a calibration or exhaust tuning change for ’24. The inconsistency between vehicles makes it feel like a build or revision issue rather than “that’s just how it is.”
I haven’t seen a confirmed fix yet, but a few people have opened cases with Jeep corporate and were told engineering is “aware.” If this is a software or exhaust revision problem, the only real solution is going to come from Jeep, not aftermarket parts. I’d definitely encourage everyone affected to open a case so it gets documented numbers matter if we want a real response.

Agreed.
Something has changed in these affected vehicles to account for this massive drone.
Every affected owner should have this documented at the dealer level. My shop foreman has no idea how to fix it and has asked for Jeep support but he was ignored and told it was designed to have that drone. This is totally False. Obviously.

I have emailed Bob Broderdorf, Jeep's CEO, and followed up with him with 9 emails, and he has not responded. I have asked for a few minutes of his time to discuss our concerns on the telephone. Not much to ask, in my opinion. I am obviously unimpressed. Each email has linked this thread and included my dealership Work Order documenting the drone as being "loud and untolerable" - Shop Foreman's words, not mine.

All affected owners need to document the problem at the dealer level and Demand Answers.

 

[Mr.patriot1776]

You’re definitely not crazy, and you’re not alone. A lot of 2024 owners are reporting the exact same low-frequency boom in that RPM range, especially on decel, and the fact that exhaust swaps and ANC deletes don’t fix it really points to a calibration or exhaust tuning change for ’24. The inconsistency between vehicles makes it feel like a build or revision issue rather than “that’s just how it is.”
I haven’t seen a confirmed fix yet, but a few people have opened cases with Jeep corporate and were told engineering is “aware.” If this is a software or exhaust revision problem, the only real solution is going to come from Jeep, not aftermarket parts. I’d definitely encourage everyone affected to open a case so it gets documented numbers matter if we want a real response.

Too late for me I already solved it. Honestly couldn't be happier with my lucky mistake.

 

[MaLuco]

Hi everyone, thought I'd check in after a while.

Canadian392 your perseverance and focus can only be matched by the level of ignorance of Jeep leadership. Just like you, I was ignored by Bob Broderdorf all while him making a number of public appearances with Jeep enthusiasts (which he proudly shared on Linkedin). Apparently, some people fill corporate jobs while other few carry true mission with passion. "documented numbers matter if we want a real response" is exactly what I have done and will continue encouraging everyone I can.

The drone on my 392 continues to exist albeit reduced by 20-30% perhaps (subjectively speaking). NoLimitz by Zautomotive disables the MDS without the need to resort to the Offroad+ mode (which is less advised on paved roads - safety). HotHeads headliner for the SOT has contributed a bit (it has been on my mods list for highway driving noise reduction anyway and oh boy does it make a difference). Next, Sound Assassin by HotHeads (again more for the overall noise reduction).

The true drone solution seems to be what MRT is conceptually doing: adding a resonator or J-pipe tuned to the offending frequency. In practical terms this means:

• Measuring my specific drone frequency in an exhaust shop (just in case it's unique enough on my 392).
• Calculating a Helmholtz length or choosing a resonator to target that band.
• Welding that into my existing system without deleting cats or active valves.

I am loving my 392. I hope this is the last Jeep I'll ever need to buy.

 

[MaLuco]

Too late for me I already solved it. Honestly couldn't be happier with my lucky mistake.

Super happy for you! Which drone specifically were you able to address with your fix (intensity, RPM band, other conditions). Thanks a lot!

 

[Canadian 392]

Hi everyone, thought I'd check in after a while.

Canadian392 your perseverance and focus can only be matched by the level of ignorance of Jeep leadership. Just like you, I was ignored by Bob Broderdorf all while him making a number of public appearances with Jeep enthusiasts (which he proudly shared on Linkedin). Apparently, some people fill corporate jobs while other few carry true mission with passion. "documented numbers matter if we want a real response" is exactly what I have done and will continue encouraging everyone I can.

The drone on my 392 continues to exist albeit reduced by 20-30% perhaps (subjectively speaking). NoLimitz by Zautomotive disables the MDS without the need to resort to the Offroad+ mode (which is less advised on paved roads - safety). HotHeads headliner for the SOT has contributed a bit (it has been on my mods list for highway driving noise reduction anyway and oh boy does it make a difference). Next, Sound Assassin by HotHeads (again more for the overall noise reduction).

The true drone solution seems to be what MRT is conceptually doing: adding a resonator or J-pipe tuned to the offending frequency. In practical terms this means:

• Measuring my specific drone frequency in an exhaust shop (just in case it's unique enough on my 392).
• Calculating a Helmholtz length or choosing a resonator to target that band.
• Welding that into my existing system without deleting cats or active valves.

I am loving my 392. I hope this is the last Jeep I'll ever need to buy.

Yes. MRT is on point and they appear to understand the drone Problem.

All forum members with this drone problem, have the problem documented at the dealer level.

To say I am unimpressed with Bob Broderdorf’s lack of response to my numerous emails (and yours) is an understatement.

No CEO is too busy for a 5 min call scheduled around one’s own timeline.

I will continue my efforts and advocate for affected owners.

 

[Mrwheelservice]

Just was searching the forum for droning issues. I have a 21’ with 36k miles. Mine just recently started the drone. It appears this is a known issue, while mostly 24MY, I wonder do other years have the issue? I have noticed the exhaust getting louder over the last 15K miles (not mad about that) but in the last 2K miles mine is starting to drone horrible. Notice it most when cold and lower RPM. Curious about the cerikote painting, if nothing else it looks good. Also very anxious about a solution from MRT! Keep us posted!

 

[OldVetteGuy]

Exhaust drone is one of those interesting things, many things can directly effect the exhaust note and sound.

A few of these things are the hardware itself, tube size, muffler baffling, crossover/x-pipe engine RPM at cruse and finally tune.

The 392 in the Wrangler initially was equipped with 373 gearing with is the majority of pre 24 Hemi Wranglers. The problem did not seem to be mainstream until the 24/25 MY with the 456 gearing as standard equipment.

If you drive a 373 equipped Jeep at cruising speed is about 2300 RPM, up the gear ratio to 456 at the same speed and your at nearly 2900 RPM, right at the sweet spot for droning on the Hemi. Now consider that the Hemi with 373 is pulling a bit harder the MDS does not come online as quickly as in the 456 gearing model.

I can tell you first hand MDS really changes the exhaust note (and not for the better) and another reason for NoLimitz, MDS disable!

I have a friend that recently swapped out the x-pipe and resonator for the MRT replacement and it changed the exhaust note to a deep less raspy sound and eliminated the pop on deceleration, this was on a 23 392 , though.

What is the answer? There are too many factors at play here and its going to take Jeep engineers in a test environment to fully provide the answers. Don't lay awake at night waiting on this one, I think a majority of their power plant engineers are working on how to keep the 392 in other Wrangler/Gladiator platforms and not the sound of the exhaust of past platforms.

Stellantis isn't going to spend any money on this one. So, it's up to us to find the answers, MRT, AWE hopefully will help with this one and hopefully new Moab 392 can also share their findings if Stellantis does change the exhaust we will see it here. One thing is for sure we have all come a long way from the Cherry Bomb exhausts of the seventies!

Personally few things in the automotive world that are sweeter then the full tilt exhaust of a large displacement engine (without pops, raspy sounds, backfires, droning and so on) just pure engine sound, not noise and the sound of high horsepower screaming out the exhaust! I have seen many in my day, the 392 in the Jeep is close but it hasn't quite been mastered yet IMHO!

For now, keep the vertical pedal smashed and the smile and the wave alive! Cheers all and a Happy New year!

 

[Mr.patriot1776]

Super happy for you! Which drone specifically were you able to address with your fix (intensity, RPM band, other conditions). Thanks a lot!

It was in the RPM band of 2000 to like 3,500 I think and was mostly the decelerating as others have described or when light on the gas in traffic or around town. I haven't heard any drone. And my son has completely stopped complaining about it.

 

[Canadian 392]

It was in the RPM band of 2000 to like 3,500 I think and was mostly the decelerating as others have described or when light on the gas in traffic or around town. I haven't heard any drone. And my son has completely stopped complaining about it.

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.

 

[OldVetteGuy]

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.

Is it possible MDS is active? This is one of the things I noticed with MDC on my 25, it went away when I installed the Nolimitz and disabled MDS.

 

[Canadian 392]

Is it possible MDS is active? This is one of the things I noticed with MDC on my 25, it went away when I installed the Nolimitz and disabled MDS.

Is it possible MDS is active? This is one of the things I noticed with MDC on my 25, it went away when I installed the Nolimitz and disabled MDS.

Off Road +, which should be disabling MDS does not help. Unless somehow MDS is still active with Off Road + being active. The dash always indicates V8 mode when Off Road + is activated. I also suspected MDS initially too.

 

[OldVetteGuy]

Off Road +, which should be disabling MDS does not help. Unless somehow MDS is still active with Off Road + being active. The dash always indicates V8 mode when Off Road + is activated. I also suspected MDS initially too.

I can tell you first hand before I installed the Nolimitz, Off Road plus was not disabling MDS and even though I did not see 4cyl mode on the dash display I could definitely tell by the sound and feel of the 392 it was activating. There are others on the forum that have had the same results.

What I will do later in this week when I get around to it: Is turn MDS back on in the Nolimitz and see if I can definitely prove that when in the Offroad plus mode MDS is still working!

 

[BarneyM]

Off Road +, which should be disabling MDS does not help. Unless somehow MDS is still active with Off Road + being active. The dash always indicates V8 mode when Off Road + is activated. I also suspected MDS initially too.

It seems the settings in Off Road + are all over the place. On my 2022 with Off Road + active my MDS is still working. Some others that is not the case. The NoLimitz definitely turns the MDS off.

 

[Canadian 392]

I can tell you first hand before I installed the Nolimitz, Off Road plus was not disabling MDS and even though I did not see 4cyl mode on the dash display I could definitely tell by the sound and feel of the 392 it was activating. There are others on the forum that have had the same results.

What I will do later in this week when I get around to it: Is turn MDS back on in the Nolimitz and see if I can definitely prove that when in the Offroad plus mode MDS is still working!

That would be some strong evidence, for sure! Please let us know

 

[Mr.patriot1776]

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.

Oh, I certainly didn't sit and take notes and document where in the RPM range it was coming from. I just know that my son would complain when he heard it and I would usually turn on the performance exhaust. Like I said it never bothered me. I grew up with load v8s. I work construction so I probably have hearing loss too. Lol .

 

[Winston]

I can tell you first hand before I installed the Nolimitz, Off Road plus was not disabling MDS and even though I did not see 4cyl mode on the dash display I could definitely tell by the sound and feel of the 392 it was activating. There are others on the forum that have had the same results.

What I will do later in this week when I get around to it: Is turn MDS back on in the Nolimitz and see if I can definitely prove that when in the Offroad plus mode MDS is still working!

Did you ever do this?

 

[OldVetteGuy]

Yup , I monitored the MDS solenoids and according to my Xtools D9 they would stay activate or activate even when the EVIC did not reflect the 392 WAS NOT in the 4 cylinder mode. This seemed to happen when I was coasting or slowing down.

I would love to have the factory Witech tool to do a better job of analyzing the findings. I can actually hear when the MDS is activated by listening to the exhaust, it matches the MDS solenoids being active on the Xtool.

Bottom line the 4 cylinder mode DOES influence the drone we hear and it doesn't always show on the EVIC.

I am going to do more work on this, I have emailed Xtools to see what options I can use to possibly capture more definitive info I could share with Stellantis.

 

[Winston]

Yup , I monitored the MDS solenoids and according to my Xtools D9 they would stay activate or activate even when the EVIC did not reflect the 392 WAS NOT in the 4 cylinder mode. This seemed to happen when I was coasting or slowing down.

I would love to have the factory Witech tool to do a better job of analyzing the findings. I can actually hear when the MDS is activated by listening to the exhaust, it matches the MDS solenoids being active on the Xtool.

Bottom line the 4 cylinder mode DOES influence the drone we hear and it doesn't always show on the EVIC.

I am going to do more work on this, I have emailed Xtools to see what options I can use to possibly capture more definitive info I could share with Stellantis.

Good findings. FWIW, before nolimitz off-road+ kept MDS off for me. 24 MY. Now I have nolimitz and still drive in off-road+ because race car.