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Discussion Starter #1
All, I am moving this discussion from another ChallengerTalk thread and starting its own new thread here. To continue:

I have a 2019 Charger SXT (basically same a Challenger and 300). I bought it new last April, and since my first weekend of ownership, there has been a loud “THUMP" or "WHUMP" from underneath the car about every 5-10 starts. It is super intermittent, and I cannot discern a pattern. It definitely is not coming from the front. Imagine someone underneath the car or in the trunk hitting the structure with a big rubber hammer - one big, solitary THUMP!

It may go a week without doing it, or it may do it two-three times in one day. One thing it has never done is thump first thing in the morning while cold, but it will do it on a cold start in the afternoon. It is more likely to happen, I think, when the car is warm after having been run but not exclusively. The first time it happened, I thought someone next to me had slammed their door really hard.

My first thought was the exhaust was hitting the bottom of the car. I took it to my dealer twice and was told there are no interferences. I was able to get it to do it once in the presence of a service advisor. I left it over a weekend, and he said his techs were able to duplicate it, and it was coming from the stereo because of a voltage spike. It really did not sound like this to me, but my car does have the premium Alpine stereo, and frequently it does sound like it is coming from the subwoofer area. I was told there was a upcoming software upgrade that would fix the problem.

A couple of weeks ago, my dealer installed a software update, and it has made no difference whatsoever.

Some have suggested a backfire. Maybe it is, but it does not sound exactly like one, and I frequently start the car from outside using remote start, and every start from outside the cabin sounds perfect.

Oh, well, I’m not letting this drop. I really believe the dealer does not know what to do, because they have no guidance from FCA. I have bought the factory service manual, and it gives no guidance in this area at all. If it is a radio/stereo problem, the only advice given is to simply replace the faulty parts. There is not much diagnostic guidance given. I have recommended to the dealer to consider replacing either the head unit, amplifier, subwoofer - anything to narrow this down (if it is stereo-related).

I spoke to two other Dodge dealers in an adjoining state, and they had never heard of this problem, either. I’m not sure FCA is onto this problem at all, but I have opened up TWO cases, the latest with a Dodge Cares rep who contacted me on the ChallengerTalk forum. Both my cases were closed with no resolution and with no notification to me they had been closed. I had to contact them to find out the status of the cases. The only "help" offered by Dodge Cares was to tell me to contact my dealer, who is not motivated to run this down but did tell me to contact Dodge Cares, who tells me to contact the dealer, who tells me to contact... Well, you get the idea.

My dealer says they have never heard of this problem before, and that's likely true, but the existence of the ChallengerTalk thread shows we are not alone in this. Unfortunately, I feel like FCA has left it in the hands of its customers to figure this problem out, even as the cars are still under full warranty.

If I get any kind of path forward from anyone, I will post here.

Please weigh in.
 

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You are not alone. My wife's 2019 Charger SXT does the exact same thing. Not all the time. When I do hear it....it sounds almost exactly like you describe. I'm not so sure it's not vacuum related. Maybe somehow thru the AC/heater ducting??? The first time I heard it, I thought what the heck is that??? Looked under car, under hood etc. The next time I changed oil I used the remote to start it as I laid off to the side of car. Didn't do it then. But I did check exhaust for hitting, being loose etc. Nothing. I'll be watching this thread.
 

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Discussion Starter #3
Thanks for the reply. I got someone on the Charger Forum to reply to my similar post over there, and they told me they had a Charger with the Rallye package that did the exact same thing. They said they removed the subwoofer from the car and found the electrical connections going into it to be loose from the factory. They applied some dielectric grease to the connections and made sure the connections were tight before putting the subwoofer back in. Reportedly, the noise stopped, but the other person over also said they had gotten into the habit of turning the stereo volume totally down before turning the car off, so they cannot be sure this actually fixed it. I plan to take my car to the dealer next week to get a whining real axle dealt with (another saga) and will ask him to check these connections. Maybe he will find something. Maybe not. Dealing with my dealer has been quite the frustrating experience, and I’m never sure what to expect when I take my car there. It’s rarely good.

I‘ll post here anything that may shed light on this. I hope you will do the same.
 

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At this point I believe the noise we are hearing on intermittent startup is a small backfire in the exhaust.
 

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Discussion Starter #5
That is plausible. The thump is so usually loudest and certainly focuses in the rear of the car most of the time, but other at some times the noise can feel as it is coming from beneath the passenger seat. There were a few starts that sounded like the WHUMP came from the front, but they are very rare, and are not nearly of such high volume. if this is happening, can any backfiring from the exhaust be heard? I have been listening and have heard nothing but normal, smooth startups outside the car.
 

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Discussion Starter #6
At this point I believe the noise we are hearing on intermittent startup is a small backfire in the exhaust.
That may be. I’ve tried to use the remote start to catch some kind of backfire coming out of the exhaust. So far, nothing for me. If it is a backfire, it can’t be good for the cats and mufflers, can it? Again, it would be nice for FCA to be in top of this situation.
 

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So I have a 19 Challenger GT Plus bought 4 months ago and have been experiencing the same problem. It has been exactly as described by BooDog. The thump varies from under the center of the backseat to the right and left intermittently I have been under the car a number of times. No problem with the exhaust hitting the underbody. Tried remote start while under the car to no avail. Thought about the sub woofer and removed the 27 and 37 fuses which power the radio and sub woofer to no avail. No check engine light illuminated and no codes stored. I have been to 3 dealers with this problem and opened a case with Dodge. The last dealership we were able to duplicate the condition. They did replace the right Cat as it was rattling but this did not fix the problem. Mechanic now thinks it's the driveshaft. If it was the driveshaft the sound wouldn't travel to the left and right and center.IMHO. Will wait a while to see if anyone else comes up with an answer. I don't want to rebuild the car but I don't want to hear this thump either. Please post any info........Thanks
 

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Discussion Starter #8
So I have a 19 Challenger GT Plus bought 4 months ago and have been experiencing the same problem. It has been exactly as described by BooDog. The thump varies from under the center of the backseat to the right and left intermittently I have been under the car a number of times. No problem with the exhaust hitting the underbody. Tried remote start while under the car to no avail. Thought about the sub woofer and removed the 27 and 37 fuses which power the radio and sub woofer to no avail. No check engine light illuminated and no codes stored. I have been to 3 dealers with this problem and opened a case with Dodge. The last dealership we were able to duplicate the condition. They did replace the right Cat as it was rattling but this did not fix the problem. Mechanic now thinks it's the driveshaft. If it was the driveshaft the sound wouldn't travel to the left and right and center.IMHO. Will wait a while to see if anyone else comes up with an answer. I don't want to rebuild the car but I don't want to hear this thump either. Please post any info........Thanks
I have posted this problem on this Challenger forum, as well as Chrysler 300 and Charger forums because the cars are all so similar. I have had a few responses from other owners who relate this same problem. Not many. One thing I note in common among all is this problem seems afflict only the V6 cars (SXT and GT). So far, I have not heard anyone relate it who has a V8 car. Your experiment removing the fuses tells me a lot, in that the problem is not likely related to the sound system.

Before everyone went into quarantine, I got my Charger back from the dealer where they replaced the rear differential under warranty (a three week ordeal). While it was there, I asked them to remove the subwoofer and check its connections. Someone posted on one of the forums that they had this thump, and they found the subwoofer connections were loose. They cleaned the connections, applied some dielectric grease, and connected everything back up. This person reported their thump went away. Regrettably, my dealer could not confirm whether or not they performed this work while they had my car. Oh, well. Still, I have not since heard the thump, but because we are all quarantined, my car has not been driven much.

Anyway, if it is not in the sound system, I am now leaning towards the problem being some kind of backfire or fuel/air puff in the exhaust system that is isolated to the V6 cars. I THINK the GT and SXT cars have different configurations, don’t they? Isn’t the exhaust system the reason the GT cars are rated about 8 hp more than the SXT cars? If, so, the thump must not be related to a particular exhaust configuration. If it is a backfire or puff, I have been concerned it could damage the catalytic converters and your experience may confirm my concerns. If, so, this problem could expose us to some expensive exhaust repairs after the warranties run out.
 

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SXT and GT have the same HP specs and exhaust. Still no idea on the problem though, no issue on mine

A Guy
 

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Discussion Starter #10
In 2019, the year of my car, the SXT was rated at 292 hp. The GT was rated at 300 hp. I was thinking it was differences in the exhaust system that accounted for this.
 

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This is funny


I thought my R/T just idled rough because its a v8...


OP do you see any dips in RPM when you experience this thump?
 

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Seems to be a common problem but no clues to what it could be.
 

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In 2019, the year of my car, the SXT was rated at 292 hp. The GT was rated at 300 hp. I was thinking it was differences in the exhaust system that accounted for this.
In a Challenger? 2019 SXT RWD/AWD 305HP, 2019 GT RWD/AWD 305 HP, hasn't changed since the 3.6L came out. You're thinking the RWD Charger SXT and GT

In the Charger SXT RWD was 292, SXT AWD 300, GT AWD/RWD both 300. Not sure why the difference there

A Guy
 

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Discussion Starter #14
This is funny


I thought my R/T just idled rough because its a v8...


OP do you see any dips in RPM when you experience this thump?
When I hear the noise I hear, the car is not really running. It happens right after the car kicks over on startup, maybe at most a half a second after the car fires off and is actually running on its own. The engine and tach have not had nearly enough time to stabilize by the time this thump happens.
 

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Discussion Starter #15
In a Challenger? 2019 SXT RWD/AWD 305HP, 2019 GT RWD/AWD 305 HP, hasn't changed since the 3.6L came out. You're thinking the RWD Charger SXT and GT

In the Charger SXT RWD was 292, SXT AWD 300, GT AWD/RWD both 300. Not sure why the difference there

A Guy
You are right. I stand corrected. I have a Charger, and I forgot I am posting this on a Challenger forum. I tend to confuse myself bouncing between these Charger, Challenger, and 300C forums.
 

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I know that my `19 SXT certainly experiences it. A couple of things are possible, and one is a backfire in the exhaust during startup, however, since it's always located on the passenger side, and is the sound of an object coming into contact with the underside of the vehicle itself, (a unique sound that nothing else produces) I would suspect it is engine wrap-up at startup and possibly an exhaust component coming into contact with the floorboard, or the passenger motor mount hitting it's limit stop. I've not yet had the ability to both look at the underside and operate the start at the same time. I may yet place a camera underneath and try that.
 

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Discussion Starter #17
I have had my dealer put my car up on lifts twice and repeatedly start and restart the car while standing underneath. They insist nothing is hitting anything else on the body. But, since this is an unpredictable, impossible to predict phenomenon, I doubt its is happening while they are looking at it. Oh, well. I can’t live at the dealer full time in the hopes someone lucks out, replicates the noise, then finds the initiative to actually troubleshoot it.

A poster in one of the blogs said his dealer was able to fix the noise by removing the (loose) writing from the factory mounted subwoofer, first cleaning the connections nicely and putting them on securely, as they were loose from the factory. I asked my dealer to check my car while he replaced the rear differential that whined from new. They kept my car 3 weeks, and when I picked it up, the Service Department could offer no proof the subwoofer check had even been done, My car continues to WHUMP on some startups. This morning, I visited my doctor, driving my car to there about 20 minutes. After the 90 minute visit, I started the car and heard what I think is the loudest WHUMP from the right rear I have heard to date. Subwoofer, backfire, motor mounts...why can’t FCA take the lead and fix this problem? FCA appears totally indifferent. What ever happened to Zone Reps and Field Service Engineering? I want a face-to -face meeting with a technical person other those geniuses at my Service Department.

i had at least two Cases opened with Dodge Cares, Both were closed out with no resolution and without my being informed they had been closed. Dodge Cares is merely window dressing that looks and smells like Customer Support. It has nothing to offer. I have seen no Customer Support of tangible value come from them.
 

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I have had my dealer put my car up on lifts twice and repeatedly start and restart the car while standing underneath. They insist nothing is hitting anything else on the body. But, since this is an unpredictable, impossible to predict phenomenon, I doubt its is happening while they are looking at it. Oh, well. I can’t live at the dealer full time in the hopes someone lucks out, replicates the noise, then finds the initiative to actually troubleshoot it.

A poster in one of the blogs said his dealer was able to fix the noise by removing the (loose) writing from the factory mounted subwoofer, first cleaning the connections nicely and putting them on securely, as they were loose from the factory. I asked my dealer to check my car while he replaced the rear differential that whined from new. They kept my car 3 weeks, and when I picked it up, the Service Department could offer no proof the subwoofer check had even been done, My car continues to WHUMP on some startups. This morning, I visited my doctor, driving my car to there about 20 minutes. After the 90 minute visit, I started the car and heard what I think is the loudest WHUMP from the right rear I have heard to date. Subwoofer, backfire, motor mounts...why can’t FCA take the lead and fix this problem? FCA appears totally indifferent. What ever happened to Zone Reps and Field Service Engineering? I want a face-to -face meeting with a technical person other those geniuses at my Service Department.

i had at least two Cases opened with Dodge Cares, Both were closed out with no resolution and without my being informed they had been closed. Dodge Cares is merely window dressing that looks and smells like Customer Support. It has nothing to offer. I have seen no Customer Support of tangible value come from them.
One thing I can assure you, it isn't the subwoofer.
 

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Discussion Starter #19
I have to believe you. I focused on the subwoofer first, because the noise sounds to me to come from that area. Another poster on one of these blogs said he pulled the radio fuse and the subwoofer fuse, and the noise was still there. Yet another poster said his car makes the noise and he has had to have catalytic converters replaced. That is just what I would expect if there are backfires or gas puffs happening in the exhaust. We all may see cat damage.
 

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I remember there was a TSB where the rear deck would rattle from the sub woofer. Wonder if it could be related?
 
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