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2016 srt 392 6.4. Just started not long ago, the car shakes when in park or idle at a red light or any stop. Never happened, now always happened. Car has 130000 kms and still under extended warranty. At first I took to get full fuel system treatment, paid 100 bucks and no results. So took to dealer for warranty service as I identified as issue and they came back with I need to change spark plugs. Didn't feel right about that because manual says 160000 km change of those, and no, I baby the car, little too much, and never track driven or stomped. I also have srt 392 2015 with 132000 kms and this issue does not exist. Any ideas to give me to give a possibly incorrect dealership some clues to look for? Thabks so much for the help!!
 

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I would start by looking at coil packs and/or all the connections too. Then if you find nothing maybe take their advice and change out the plugs like they said, just to rule that out.
 

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I would start by looking at coil packs and/or all the connections too.
Thanks so much. I feel this is an issue that needs to be repaired. This dealership is good, but finicky when identifying an issue. I had head light intermittently go off and back on again. They said I needed bulb but didn't feel right at assessment. I stuck my heels into ground and they ended up finding a bad fuse for example. Got fixed under warranty and light fine now, saved the price of bulb purchase which wasn't issue. I'm trying to find things I can throw at them with this rattling issue because I feel it is not just change the spark plugs and all good again. Something else going on here. Would like as many suggestions to cause this as possible.
 

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Discussion Starter #5
Did you ask them to reflash the computer and any other updates.
No. I'm actually horrible with cars and that solution was not presented to me by dealership. Only the spark plug change which I know is weird because the 2015 has more kms and not doing this, and spark plugs in manual say 160000 and car only at 126000 and never driven hard to force that number closer. I'm close with the service manager so if I can say try this or that it may spark something beyond his quick assessment of a spark plug change. I'm just trying to arm myself with some suggestions they can go after. Was actually hoping someone here might have had exact issue and said solution they provided that I can relay to service manager. I have feeling spark plug change and money spent too early will not resolve this. The car shakes at stop noticeably and started about a week ago and has not gone away. Car performs fine everywhere else. Other srt more kms not exhibiting the shake.
 

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2016 srt 392 6.4. Just started not long ago, the car shakes when in park or idle at a red light or any stop. Never happened, now always happened. Car has 130000 kms and still under extended warranty. At first I took to get full fuel system treatment, paid 100 bucks and no results. So took to dealer for warranty service as I identified as issue and they came back with I need to change spark plugs. Didn't feel right about that because manual says 160000 km change of those, and no, I baby the car, little too much, and never track driven or stomped. I also have srt 392 2015 with 132000 kms and this issue does not exist. Any ideas to give me to give a possibly incorrect dealership some clues to look for? Thabks so much for the help!!
You take the car in for a problem and yet overrule the diagnosis. Keep in mind while the spark plug change may not be due yet, the dealer may have experience with other similar cars that indicate the spark plugs do not have quite the service life the factory change schedule assumes.

Have to mention that with other cars I've had the plugs changed on schedule (from 24K miles to 60K miles depending upon the car/engine) and not once has the engine reacted to the new plugs. This is kind of comforting because it indicates the plugs have not deteriorated to the point they are noticeably affecting the engine. However, Dodge may not be so conservative and the plug change schedule is border line. And in some cases the change schedule can be affected by how the vehicle is driven.

Maybe plugs aren't due to be changed but have you done the engine air filter and fuel filter on schedule?

With another car I let an engine air filter go too long and while I don't recall the engine manifesting any untoward behavior before hand after I replaced the filter the engine ran noticeably better.

Also, that you "baby" the car may account for the engine's behavior. While I don't "baby" my Hellcat -- but I don't drive it like I stole it either - just took my Hellcat on a 60 mile drive the other day and even before I had reached my destination the engine was running better. My experience over the years is cars (engines) just like to get out and run once in a while. No need to drive car like you stole it. Just drive the car down the highway/freeway. The trip the other day has some 40 miles or so of freeway driving at 65mph to 70mph (or a bit faster) but 20 miles of driving county 2 lane roads with max. speed of 55mph.

Related to how you drive the car, fuel system/engine deposits can play a role. Even though my work commute of 30 miles consists of a majority of miles on the freeway which I sort of expected would suffice to keep the engine "clean" I have also noticed a change for the better when using Chevron Supreme. This after fueling the engine with a steady diet of Shell V-Power. After not even a tank of the Chevron gasoline was consumed the engine had perked up and this from just my normal usage, too, no long highway trips.

Which reminds me has the behavior continued over several fill ups? Never happened to me in around 1M miles of driving and who knows how many fuel stops but some owners are not so lucky and have gotten "bad gas". In a few cases the engine really reacted in such a way bad gasoline was a pretty easy / quick diagnosis. But in other cases the behavior is a bit more subdued but still out of character.
 

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As Rockster said, take it for a good long highway run if you cant and stomp on it several times. Blow some of the carbon out of the motor and off the pistons/plugs and see if runs better. Babying the car 100% of the time can be just as bad or worse for the motor than running it hard. If nothing else its free and the car might run better.

Just because your manual says they plugs arent due to be changed until 160k doesnt mean they wont have to be changed sooner or sometimes later. Its just a guideline, not a drop dead date when they will fail.
 

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Discussion Starter #8
You take the car in for a problem and yet overrule the diagnosis. Keep in mind while the spark plug change may not be due yet, the dealer may have experience with other similar cars that indicate the spark plugs do not have quite the service life the factory change schedule assumes.

Have to mention that with other cars I've had the plugs changed on schedule (from 24K miles to 60K miles depending upon the car/engine) and not once has the engine reacted to the new plugs. This is kind of comforting because it indicates the plugs have not deteriorated to the point they are noticeably affecting the engine. However, Dodge may not be so conservative and the plug change schedule is border line. And in some cases the change schedule can be affected by how the vehicle is driven.

Maybe plugs aren't due to be changed but have you done the engine air filter and fuel filter on schedule?

With another car I let an engine air filter go too long and while I don't recall the engine manifesting any untoward behavior before hand after I replaced the filter the engine ran noticeably better.

Also, that you "baby" the car may account for the engine's behavior. While I don't "baby" my Hellcat -- but I don't drive it like I stole it either - just took my Hellcat on a 60 mile drive the other day and even before I had reached my destination the engine was running better. My experience over the years is cars (engines) just like to get out and run once in a while. No need to drive car like you stole it. Just drive the car down the highway/freeway. The trip the other day has some 40 miles or so of freeway driving at 65mph to 70mph (or a bit faster) but 20 miles of driving county 2 lane roads with max. speed of 55mph.

Related to how you drive the car, fuel system/engine deposits can play a role. Even though my work commute of 30 miles consists of a majority of miles on the freeway which I sort of expected would suffice to keep the engine "clean" I have also noticed a change for the better when using Chevron Supreme. This after fueling the engine with a steady diet of Shell V-Power. After not even a tank of the Chevron gasoline was consumed the engine had perked up and this from just my normal usage, too, no long highway trips.

Which reminds me has the behavior continued over several fill ups? Never happened to me in around 1M miles of driving and who knows how many fuel stops but some owners are not so lucky and have gotten "bad gas". In a few cases the engine really reacted in such a way bad gasoline was a pretty easy / quick diagnosis. But in other cases the behavior is a bit more subdued but still out of character.
Thanks for this. There is more to the story than I was able to list. Srt cars out here are like unicorns. Everytime I pop into the dealership it's like theor seeing one for the first time. It get political when I need legit warranty work and they can't find the problem. There have been multiple instances where I went in with a mechanical issue and I was left with an answer to buy something to fix it, and after some push from my end they would end up finding a genuine issue under warranty and the problem would resolve, and it ended up not being what they told me to buy. It's honestly awesome having two identical srt chargers separated by only one year. Wife and I just get into which ever one. So the act the same and great to compare to. Both cars are daily drivers, I'm mostly in the one I'm discussing right now, I commute to work on a paid highway allowing me to do 125 kms for about 35 mins each way everyday to work. As for babying the car I meant I don't track it or drive it like it's stolen. But it is driven openly. As for gas, yes lots of top ups since the issue. Same gas station I have used since owning same 91 octane, same for both cars. I was trying to detail that a shorter life span of plugs may not be merited due to my actual use. Because of my work I can only drop car first thing in morning before work, then take the other, leaving car with them all day with an issue to diagnose and resolve. It's disappointing when I pickup after leaving all day only to hear I have to buy something to resolve issue that's still there. Which is fine, but again, have had times when they said one thing and after some push, they did find an unrelated solution to problem that actually was that had nothing to do with their purchasing suggestion to resolve. Just trying to see if someone here had a similar issue so I can go back and say hey, try this. Which has happened and helped before after some research on my end after they told me to pay for something. I'm going to try another dealership but this one I go to is technically the best option for my srt. Thanks again.
 

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Can you be more specific about your symptoms? I have a 2015 SRT Charger with about 50k miles on it and mine sometimes shakes at idle as well. I will try to pay more attention to it, but specifically when stopped at a stoplight the car will shake in time with the engine. Does the shake change or stop when you put it in neutral? I'm not too worried about it as it's a fairly large engine and it kind of makes sence to me that at such low idle the engine would rock the car a bit. What suspension settings are you using? I have mine set to street/soft so maybe that may play a part in the car shaking a bit more at idle?

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Discussion Starter #10
Can you be more specific about your symptoms? I have a 2015 SRT Charger with about 50k miles on it and mine sometimes shakes at idle as well. I will try to pay more attention to it, but specifically when stopped at a stoplight the car will shake in time with the engine. Does the shake change or stop when you put it in neutral? I'm not too worried about it as it's a fairly large engine and it kind of makes sence to me that at such low idle the engine would rock the car a bit. What suspension settings are you using? I have mine set to street/soft so maybe that may play a part in the car shaking a bit more at idle?

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Thanks for reply. It started all at once and never went away. Never felt anything like it and my other srt does not do ever. The car discussed started to do on its own and has a noticeable shake when in drive or neutral or in park. When in drive, its only noticeable when stopped at light or stop sign. The car just has a noticeable shake or vibration. In a way it's kind of cool when it started, but knew something up because never did for the prior 120000 plus kms, and never went away, and other srt has never done this before at all. That one with same driving habits, same fuel, is still acting "normal" when idle and not shaking like this car. Sorry if horrible description. Lol.
 

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Discussion Starter #11
Can you be more specific about your symptoms? I have a 2015 SRT Charger with about 50k miles on it and mine sometimes shakes at idle as well. I will try to pay more attention to it, but specifically when stopped at a stoplight the car will shake in time with the engine. Does the shake change or stop when you put it in neutral? I'm not too worried about it as it's a fairly large engine and it kind of makes sence to me that at such low idle the engine would rock the car a bit. What suspension settings are you using? I have mine set to street/soft so maybe that may play a part in the car shaking a bit more at idle?

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Forgot to mention , it's winter snow here so the car never leaves default drive setting with eco on. I tried changing drive mode and same thing.
 

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The dealer found no codes stored?
Was thinking this too. OP hasnt mentioned a CEL so im guessing it must not be prominent enough to be outside of the acceptable parameters. This would have me thinking it’s a small misfire if a misfire at all.
I would change the plugs just to rule it out. If it was babied and maybe it’s allowed to warm up and idle quite a bit, who knows? Maybe carbon buildup on them. If not then maybe take it to be diagnosed somewhere reputable or another dealer at the very least. If there is a history of needing to constantly prod the current dealer, it’s time to make a switch.
 

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At 120000 km I’d pull the plugs, they will tell you allot about what’s going on inside each cylinder. They all should look the same, if any look different it’s a clue, You may have a bad or fouled injector or just a fouled plug from babying if too much, or a weak coil pack or bad or even just wet wire. Changing plugs, if done by a skilled technician, not just a wrench turner who’s going to pull them, toss them, and put new ones and have blinders on or not be looking for issues isn’t what your looking for. I’d want them all saved and marked what cylinder they came from.
 

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125km per hour is 77mph. At 35 minutes this works out to around 44 miles. That's pretty close to what mileage I found out seems to make a difference in how my car engines run. My 30 mile commute (and not all of this at even 65mph let alone 77mph) was just not enough highway miles. But a 40+ mile drive proved to make a difference which kind of surprised me.

So it would seem as you touched upon while you "baby" the car you do drive car down the highway at a good clip and for a good distance.

I have no experience with Dodge engines and plug life. As I think I mentioned with other brands of cars the plugs even at 60K miles were "fine" that is based on the fact new plugs didn't result in any change (good or bad) from the engine but that doesn't mean plugs in Dodge engines will fare the same.

While I'm not a fan of throwing parts at untoward behavior in this case I could be tempted to replace the plugs. If only to try to get a feel for if the new plugs make a difference or not.

As an aside with another car at 132K miles I had all 4 O2 sensors replaced. This was prompted by one triggering a CEL and the car was due for a smog check and I wanted it to pass. However, other than the CEL the engine was not manifesting any untoward behavior. The CEL came on at a station in Barstow CA and I drove the car 320+ miles home with no sign of any issues other than after every fill up the CEL came on after engine start. And same code. After the new sensors were installed the engine ran noticeably better.

Then at around 140K miles but with the engine not manifesting any signs of any problems I had the coils and plugs changed. Just curious given the difference new O2 senors made. The plugs were about 10K miles from their replacement mileage but the tech recommended the plugs be replaced at the same time and given how much labor is required to access the coils and plugs I agreed.

Rather surprisingly to me the engine ran better after. Since I had had the plugs replaced several times before at the required miles with no change in how the engine ran I attributed the improvement to the new coils.

My point is even though the engine controller may not detect a problem that warrants a CEL critical hardware like coils, or O2 sensors, and this includes plugs, can require replacement, or at least the engine can benefit from their replacement.

Thus at least in my opinion a case could be made to "throw" parts at this shaking behavior and install new plugs.
 

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I know you've had problems with the dealership telling you to buy the wrong things but you're going to need to do the plugs anyway in 30kms. Think of just doing preventative maintenance early. Hell, talk to the Service Manager and ask if you can have it done at the dealership and they would refund the labor cost if that turns out to not be the issue.
 

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I’d try a fresh tank of Shell premium before getting too into it. Maybe a bottle of octane boost also. Winter fuel can be poor quality sometimes.
 

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I’d try a fresh tank of Shell premium before getting too into it. Maybe a bottle of octane boost also. Winter fuel can be poor quality sometimes.
Add some seafoam too.

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Hell, talk to the Service Manager and ask if you can have it done at the dealership and they would refund the labor cost if that turns out to not be the issue.
That actually made me literally LOL. Have you ever actually tried that at a dealer service dept? They will laugh harder than I just did. They are ruthless and in my experience will never take that responsibility on. Always someone else's fault. They love plugging in parts with your money though.
 

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I have a 2019 Scat Pack with 1500 miles on it, mine has done this on and off since I've had it. I just wrote it off to slightly aggressive timing/cam phasing.
 
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