Deep Bass Noise

[infamous212]

Can confirm. I have a 2024 392. I removed all 4 mics and still hear the deep bass on deceleration. It occurs in both auto and manual mode so it does not appear to have anything to do with cylinder deactivation. Only thing that works is throwing it into neutral when coming to a stop.

Yup. I’ve reconnected all four mic’s today and have been telling myself to just get used to the sound. It’s the engine braking followed by downshifting during deceleration is the culprit.

 

[Ten4Jeep]

Just for reference, I have a 2023 20th and I have nothing like what you described. In fact I think this Jeep is much quieter than I expected. There is a very subtle off cycle exhaust noise when the thing goes into MDS but it's barely audible.

Same here. My 2023 XR is very quiet with exhaust in silent mode. It’s incredible how quiet this vehicle is on the road, with the exception of the MDS. Only noise I get when I let off the pedal is that “decel pop”, but I love that sound

 

[Tank2112]

First time I really noticed the drone sound was in 4-low driving slowly. Right around 2,000 rpm seems to be the worst. Had to switch to Quiet mode to be tolerable.
For me, removing all four mics did help. Drone was still present but sub was not adding to the problem.
Magnaflow Street exhaust did help with drone. Dynomatt is next just to further quieten Jeep. Made a world of difference in my Ram truck.
2023 XR.

 

[Bruce Willys]

Yup. I’ve reconnected all four mic’s today and have been telling myself to just get used to the sound. It’s the engine braking followed by downshifting during deceleration is the culprit.

Ditto. Reconnecting my mics too. Deceleration is marginally less obnoxious with the performance exhaust off.

 

[Wizza]

I bought an tried the T-harness audio integration cable and it made ZERO difference, wasted the money on that item

 

[Rusty762]

Nice article on how it works:

What Is Hemi MDS?

We explain how Chrysler Hemi MDS cylinder deactivation works, what goes wrong, and how to fix it when it breaks.

www.motortrend.com

All this talk about ANC, has anyone done away with the MDS on their 392?

 

[Tank2112]

All this talk about ANC, has anyone done away with the MDS on their 392?

Good read.... thanks.

 

[Wizza]

All this talk about ANC, has anyone done away with the MDS on their 392?

the way the oiling system is set up, you are not meant to do that or you will have a lot of extra work to handle shortly thereafter

 

[Tank2112]

All this talk about ANC, has anyone done away with the MDS on their 392?

If you have a 2023, and test drive in Offroad+, it should lock out MDS so you can see if you're getting more drone while in 4-cyl mode. Not the case for me. I noticed drone worst while driving in Low-Range, which locks out MDS.

 

[392hk]

thought to share my experience with ANC/subwoofer noise.
I got my jeep from the agency, it is a certified approved car with warranty etc…
When I received it I noticed that the rear (cargo area) headliner was missing, which was highlighted to the agency and they promised to provide the missing piece when available.
Later I upgraded to the borla attak exhaust, and as I have mentioned earlier on this thread I noticed that exhaust was much more quiet than stock with performance exhaust off.
Last week I decided to make my own rear cargo area headliner from foam board, layered with felt and thermal insulation sheets. I made two panels one for each side and stuck them on with Velcro. The result was aesthetically and functionally ok. But what I noticed is that subwoofer deep bass sound kicking in aggressively in the 1500 rpm range especially when deceleration. Similar to what other are experiencing. Very annoying!!
Today I ripped these self made headliner panels off and went for a drive. And surprise the annoying sound got reduced by 70 to 80% at the same rpm range.
I think the previous owner resorted to the same solution and hence the missing piece, otherwise I couldn’t find any plausible logic to remove it.
Would appreciate if anyone else can replicate the same.
Or is it my own delusion construct!!

 

[Tank2112]

thought to share my experience with ANC/subwoofer noise.
I got my jeep from the agency, it is a certified approved car with warranty etc…
When I received it I noticed that the rear (cargo area) headliner was missing, which was highlighted to the agency and they promised to provide the missing piece when available.
Later I upgraded to the borla attak exhaust, and as I have mentioned earlier on this thread I noticed that exhaust was much more quiet than stock with performance exhaust off.
Last week I decided to make my own rear cargo area headliner from foam board, layered with felt and thermal insulation sheets. I made two panels one for each side and stuck them on with Velcro. The result was aesthetically and functionally ok. But what I noticed is that subwoofer deep bass sound kicking in aggressively in the 1500 rpm range especially when deceleration. Similar to what other are experiencing. Very annoying!!
Today I ripped these self made headliner panels off and went for a drive. And surprise the annoying sound got reduced by 70 to 80% at the same rpm range.
I think the previous owner resorted to the same solution and hence the missing piece, otherwise I couldn’t find any plausible logic to remove it.
Would appreciate if anyone else can replicate the same.
Or is it my own delusion construct!!

Could be that by adding the head liner, you quietened some wind noise from the top in the cargo area, to the point to where you noticed the underlying bass note "drone". Mine was the worst at 2,000 rpms range. Very noticeable in low-range. For me, Magnaflow Street exhaust did help reduce drone over stock exhaust. I plan on sound treating rear cargo floor area with Dynomat type product, along with all floors and doors. The drone is more than likely coming through the floor in cargo area.

 

[infamous212]

thought to share my experience with ANC/subwoofer noise.
I got my jeep from the agency, it is a certified approved car with warranty etc…
When I received it I noticed that the rear (cargo area) headliner was missing, which was highlighted to the agency and they promised to provide the missing piece when available.
Later I upgraded to the borla attak exhaust, and as I have mentioned earlier on this thread I noticed that exhaust was much more quiet than stock with performance exhaust off.
Last week I decided to make my own rear cargo area headliner from foam board, layered with felt and thermal insulation sheets. I made two panels one for each side and stuck them on with Velcro. The result was aesthetically and functionally ok. But what I noticed is that subwoofer deep bass sound kicking in aggressively in the 1500 rpm range especially when deceleration. Similar to what other are experiencing. Very annoying!!
Today I ripped these self made headliner panels off and went for a drive. And surprise the annoying sound got reduced by 70 to 80% at the same rpm range.
I think the previous owner resorted to the same solution and hence the missing piece, otherwise I couldn’t find any plausible logic to remove it.
Would appreciate if anyone else can replicate the same.
Or is it my own delusion construct!!

This is interesting find and result.

 

[392hk]

I ended up unplugging all 4 mics. And what a difference it made!!
The cabin is actually much quieter, the normal engine drone sound is still there but barely noticeable and not as annoying as the artificially generated noise from the sub. Also the quality of the audio system has improved.

 

[infamous212]

I ended up unplugging all 4 mics. And what a difference it made!!
The cabin is actually much quieter, the normal engine drone sound is still there but barely noticeable and not as annoying as the artificially generated noise from the sub. Also the quality of the audio system has improved.

This is an interesting feedback from you because I couldn’t tell any difference when I had disconnected all four mics. Do you have a full headliner including the back as well?

 

[392hk]

This is an interesting feedback from you because I couldn’t tell any difference when I had disconnected all four mics. Do you have a full headliner including the back as well?

Yes, I tried with and without the cargo area and ended up keeping it. The bass noise is completely gone.

 

[infamous212]

Yes, I tried with and without the cargo area and ended up keeping it. The bass noise is completely gone.

I’m not sure if this matters but is yours ‘24?

 

[392hk]

It’s a 2021 with borla atak

 

[Tank2112]

I ended up unplugging all 4 mics. And what a difference it made!!
The cabin is actually much quieter, the normal engine drone sound is still there but barely noticeable and not as annoying as the artificially generated noise from the sub. Also the quality of the audio system has improved.

I removed all 4 mics as well. So now, any drone is from exhaust not subwoofer attempting to cancel. I found that the ANC may work better at Hwy speeds, but while offroad in low range…. terrible low frequency tone.

 

[Young04]

Anyone take other steps to suppress the resonance? My 2021 392 only had very minor resonance. My 2024 is borderline unbearable (both SOT). I get it if I go down a hill off throttle and sometimes if I let off the gas just as a gear change is happening and the transmission "hangs" between gears or executes a slow upshift. I've unplugged all ANC mics and even unplugged the sub itself and it isn't that. I'm thinking of bringing it to a custom exhaust shop to see if they can some sort of resonator to kill the resonance without reducing the volume. Anyone else go a similar route?

 

[veddersbetter]

Anyone take other steps to suppress the resonance? My 2021 392 only had very minor resonance. My 2024 is borderline unbearable (both SOT). I get it if I go down a hill off throttle and sometimes if I let off the gas just as a gear change is happening and the transmission "hangs" between gears or executes a slow upshift. I've unplugged all ANC mics and even unplugged the sub itself and it isn't that. I'm thinking of bringing it to a custom exhaust shop to see if they can some sort of resonator to kill the resonance without reducing the volume. Anyone else go a similar route?

My 21 was an SOT... 24 is a hard top with the added insulation .. thicker front windows... and the resonance is worse. Certainly sounds like it's coming from the sub... going to unhook it and see if it helps. Its far worse than my 21.