Exhaust Drone

[Bobo57]

I don't believe it is MDS because I lock MDS out using manual mode. While driving, in traffic, it doesn't bother me but when coasting down hills off throttle, that is when it is the worst, whether in manual mode or normal including MDS.

I'll rig up a gpro this weekend and have a look at the valves. I am trying to stay away from the Z programing to maintain warranty. I just passed 3200 miles. My biggest concern about the vehicle is the transfer case and I don't want to give them any excuses. As for the lag you mention, I have noticed a lag, but I was contributing that to the clutch pack in the T-case. When I feel a lag, the engine still sounds responsive. Is that the lag you are referring to?

I've got a 23' and have zero drone, just a beautiful exhaust note when you get on it. Even with the valves open when I'm cruising on the highway it's quiet. With the valves closed it's quiet as church.
I'm betting there was a muffler design change on the 24' forward.

 

[Winston]

I've got a 23' and have zero drone, just a beautiful exhaust note when you get on it. Even with the valves open when I'm cruising on the highway it's quiet. With the valves closed it's quiet as church.
I'm betting there was a muffler design change on the 24' forward.

Something changed, that's for sure. I drove a '22, no drone complaints at all. My '24 is a different experience altogether.

 

[Canadian 392]

I've got a 23' and have zero drone, just a beautiful exhaust note when you get on it. Even with the valves open when I'm cruising on the highway it's quiet. With the valves closed it's quiet as church.
I'm betting there was a muffler design change on the 24' forward.

This confirms there is something seriously wrong with the exhaust on the 2024 model year. I drove a 2023 392 for my test drive and there was no drone either. I would have never bought this vehicle if the test drive with the 2023 had any drone.

This is all information I hope to communicate with Bob, Jeep's CEO. I have sent him multiple emails with a link to this forum thread, as well as my shop foreman's work order at the dealership indicating the drone to be loud and un-tolerable. my last follow-up email was earlier today.

 

[Canadian 392]

I am new here but not new to Jeeps. I had the 2.0JLUR, then JT Mojave, and now back to the Wrangler and without a doubt my favorite. I purchased a new old stock 2024 Final Edition which came with about everything, excluding the fancy roof top, but it did include the drone. I chalked it up as normal. After reading thought this chain, I saw the suggestion about using AI and learned a few things that I need to verify. I hear the drone most when I am off throttle and going through our neighborhood at 25-30 mph. I always drive with the "loud button" on but apparently that doesn't mean the valves are always open. Claude AI is theorizing that there may have been a change to the 2024 model year Active Exhaust Valve Programming. This needs to be verified, but it may be that when the off-throttle condition occurs, the DFCO - (Deceleration Fuel Cut-Off), the exhaust system is under vacuum instead of pressure. This completely changes the acoustic characteristics. If your active exhaust valves close during DFCO (which they might, even in Track Mode), you're creating a resonance chamber at a very specific frequency, ~72 Hz fundamental with strong 129 Hz 2nd harmonic. I am attaching the Claude AI details in a pdf document if anyone is interested.

@ ruscopin,

Excellent Work!

I think you really narrowed down the most likely explanation for the drone issues. The Deceleration Fuel Cut Off (DFCO) must be activating when completely off throttle or nearly complete off throttle while in the 1400-1900 RPM zone.

*The drone is never present while accelerating through that RPM range, only when I am completely off throttle or nearly completely off throttle in that RPM range.

* Once DFCO is activated, this would create colder/air vacuum in the exhaust system to the cylinders, instead of positive hot exhaust flow out tail pipes because the injectors turn off with DFCO in that range. I think this explains why there is no drone at all when the engine is cold for the first few minutes.

*There must be a parameter in the DFCO settings that only activities DFCO once the engine is already warmed up. At a certain operating temperature, the DFCO is activated once certain parameters are met: namely being in the 1400-1900 RPM zone AND either being completely off throttle or nearly off throttle (with very mild throttle input, even if its like only 2-3% throttle). The system still needs to have some fuel injected in our drone zone to keep the exhaust gases hot and exiting with speed through the tail pipes.

*Otherwise, when DFCO is active (zero fuel being injected), it creates the perfect storm of slower flow and or vacuum, cooler air, and excites the bad resonant frequencies in the exhaust tubes and vehicle structure producing that loud low frequency boom/drone.

* This is likely the difference between the 2024 model years, and previous years, which owners report no drone. Engineers likely changed the 2024 DFCO settings for emission standards, creating this problem.

Has anyone here unlocked their PCM and using HP Tuners or other programs that provide access to the DFCO settings??

 

[Need4Speed]

I have a minor drone under those conditions but only when it drops to 4 cylinder mode.

 

[MRT Performance]

Update: Need 2024+ 392s for Drone Solution Development!

We're moving ahead on our drone-alleviation options for the 392! We specifically need access to 2024+ 392 models to help us tweak and develop these solutions further. If you have a newer rig and want to get rid of that stock system drone, please DM us here or call us at (734) 455-5807. Let's refine these fixes!

 

[Winston]

Update: Need 2024+ 392s for Drone Solution Development!

We're moving ahead on our drone-alleviation options for the 392! We specifically need access to 2024+ 392 models to help us tweak and develop these solutions further. If you have a newer rig and want to get rid of that stock system drone, please DM us here or call us at (734) 455-5807. Let's refine these fixes!

Great talking to you on the phone, if I were closer I'd be making an appointment with you right now. Excited to see what you guys come up with. If there's any information I/we can provide from afar, please let us know.

 

[Canadian 392]

Update: Need 2024+ 392s for Drone Solution Development!

We're moving ahead on our drone-alleviation options for the 392! We specifically need access to 2024+ 392 models to help us tweak and develop these solutions further. If you have a newer rig and want to get rid of that stock system drone, please DM us here or call us at (734) 455-5807. Let's refine these fixes!

Excellent news!!!

 

[Winston]

Excellent news!!!

You making the trip over? You're much closer than me

 

[Canadian 392]

You making the trip over? You're much closer than me

Scheduling is a nightmare for me for the next few months.

I'll do everything I can immediately from Toronto to help get this solution finalized so we can all benefit. Perhaps installing some prototype mufflers etc. and sending data from a spectrum analyzer to fine tune things?

I know for certain, I will be purchasing MRT's solution. This is for sure!

 

[MRT Performance]

Hey 392 Nation,

Quick update on our 2024+ drone solution development: Today we finally got a 2024 392 in the shop for an H-Pipe install!

WOW. The stock system is truly something else.
Before tearing into it, we took the rig for a test drive with the stock system, specifically to assess its characteristics.

And WOW. We can't believe how drone-prone the stock system is. Seriously, how did that ever get a stamp of approval? The minute we pulled out of the parking spot, the drone was already inserting itself into the cabin. Under load and WOT, it sounded great, but during deceleration and cruising around the 1500-2000 RPM range, that drone was obvious and, frankly, not acceptable for a stock system.

Solution Underway... And a Backup Plan!
As we speak, we are installing our MRT H-Pipe on this 2024 392. We are confident this will make a significant difference.

However, we want to assure you: if the H-Pipe isn't the complete solution for every scenario, we have a backup plan ready to deploy. Our commitment is to eliminate this drone.

We will report back later today with the results and our initial findings! Stay tuned!

 

[Winston]

View attachment 51412​

Hey 392 Nation,

Quick update on our 2024+ drone solution development: Today we finally got a 2024 392 in the shop for an H-Pipe install!

WOW. The stock system is truly something else.
Before tearing into it, we took the rig for a test drive with the stock system, specifically to assess its characteristics.

And WOW. We can't believe how drone-prone the stock system is. Seriously, how did that ever get a stamp of approval? The minute we pulled out of the parking spot, the drone was already inserting itself into the cabin. Under load and WOT, it sounded great, but during deceleration and cruising around the 1500-2000 RPM range, that drone was obvious and, frankly, not acceptable for a stock system.

Solution Underway... And a Backup Plan!
As we speak, we are installing our MRT H-Pipe on this 2024 392. We are confident this will make a significant difference.

However, we want to assure you: if the H-Pipe isn't the complete solution for every scenario, we have a backup plan ready to deploy. Our commitment is to eliminate this drone.

We will report back later today with the results and our initial findings! Stay tuned!

Fantastic news, thanks so much for this!

 

[MRT Performance]

Quick update on our 2024+ drone solution development: As promised, we just finished installing our H-Pipe on the 2024 392 in the shop today!

After installing the MRT H-Pipe, we could tell an immediate difference!

While the drone isn't completely gone, it is a lot more tolerable now. Crucially, the drone is now competing against fantastic pops and burbles on deceleration, giving that pure performance sound without the overpowering headache of the stock system. If you're looking for significant drone reduction and a pure performance sound, this H-Pipe may be an excellent option for you.

We are letting the customer live with this new setup for a few days and eagerly await his experience report. We also know we have another H-Pipe in transit to another 392 owner and look forward to hearing their feedback as well!

Still Seeking Development Vehicles (Plan B Available!)​

For those with more discerning tastes or if the H-Pipe doesn't entirely meet individual expectations, we still have Plan B to try out! Our commitment is to find the ultimate solution.

So, we are still actively looking for more 2024+ 392s for development. If you're interested in helping us refine these fixes, please DM us here or call us at (734) 455-5807. Let's get rid of that drone together!

 

[Winston]

Quick update on our 2024+ drone solution development: As promised, we just finished installing our H-Pipe on the 2024 392 in the shop today!

After installing the MRT H-Pipe, we could tell an immediate difference!

While the drone isn't completely gone, it is a lot more tolerable now. Crucially, the drone is now competing against fantastic pops and burbles on deceleration, giving that pure performance sound without the overpowering headache of the stock system. If you're looking for significant drone reduction and a pure performance sound, this H-Pipe may be an excellent option for you.

We are letting the customer live with this new setup for a few days and eagerly await his experience report. We also know we have another H-Pipe in transit to another 392 owner and look forward to hearing their feedback as well!

Still Seeking Development Vehicles (Plan B Available!)​

For those with more discerning tastes or if the H-Pipe doesn't entirely meet individual expectations, we still have Plan B to try out! Our commitment is to find the ultimate solution.

So, we are still actively looking for more 2024+ 392s for development. If you're interested in helping us refine these fixes, please DM us here or call us at (734) 455-5807. Let's get rid of that drone together!

Thanks so much. Do you know if the H-Pipe works with the AWE Switchpath exhaust system? That's the one I'm running. I had the drone on the stock exhaust, replaced with AWE hoping to remedy and it got "worse". Sounds amazing, don't get me wrong, but the drone is much deeper and boomier around that 1800-2200 RPM range.

 

[Canadian 392]

Quick update on our 2024+ drone solution development: As promised, we just finished installing our H-Pipe on the 2024 392 in the shop today!

After installing the MRT H-Pipe, we could tell an immediate difference!

While the drone isn't completely gone, it is a lot more tolerable now. Crucially, the drone is now competing against fantastic pops and burbles on deceleration, giving that pure performance sound without the overpowering headache of the stock system. If you're looking for significant drone reduction and a pure performance sound, this H-Pipe may be an excellent option for you.

We are letting the customer live with this new setup for a few days and eagerly await his experience report. We also know we have another H-Pipe in transit to another 392 owner and look forward to hearing their feedback as well!

Still Seeking Development Vehicles (Plan B Available!)​

For those with more discerning tastes or if the H-Pipe doesn't entirely meet individual expectations, we still have Plan B to try out! Our commitment is to find the ultimate solution.

So, we are still actively looking for more 2024+ 392s for development. If you're interested in helping us refine these fixes, please DM us here or call us at (734) 455-5807. Let's get rid of that drone together!

A plan B would be great, to finally remove this drone, once and for all

 

[MRT Performance]

Thanks so much. Do you know if the H-Pipe works with the AWE Switchpath exhaust system? That's the one I'm running. I had the drone on the stock exhaust, replaced with AWE hoping to remedy and it got "worse". Sounds amazing, don't get me wrong, but the drone is much deeper and boomier around that 1800-2200 RPM range.

We would need a 392 with the switch path installed to verify fitment.

A plan B would be great, to finally remove this drone, once and for all

We are developing a new component, which we call the Muffinator. Initial results on vehicles known for exhaust drone have been significant, showcasing a design unlike any other currently available.

 

[Winston]

We are developing a new component, which we call the Muffinator. Initial results on vehicles known for exhaust drone have been significant, showcasing a design unlike any other currently available.

 

[MRT Performance]

View attachment 51424

 

[YGBSM]

We would need a 392 with the switch path installed to verify fitment.


We are developing a new component, which we call the Muffinator. Initial results on vehicles known for exhaust drone have been significant, showcasing a design unlike any other currently available.

You have to keep that name! Brilliant marketing. Add a design to advertising and packaging of the MRT Performance logo, on the Muffinator, crushing a drone.

 

[Mr.patriot1776]

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.