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Discussion Starter · #1 · (Edited)
ok so I bought this Dodge Charger scat pack with 11,000 miles very clean car. Drove it home my wife and I very excited.. well my wife drives the car daily and she tells me the car makes a vibration and a weird noise along with it when at a stop light or at the drive thru.. so I got in it and sure enough it has a stumble grinding sound coming from the engine . It almost sounds like it’s trying to misfire and stumbles trying to correct itself . I took it to the dealer they say they hear it had it in for 3 days trying to figure it out . They say they can’t make it rough idle after 3 days so I drove there start it up and walla it rough idles right away it does it ever time the car is runnin .then the mechanic kid comes out with his laptop and is reading for misfires and it’s not missing then 1 mis fire pops up . So I said it just missed right there and he’s said yeah but just one time ! I’m like I don’t think it supposed to skip a beat man his service advisor didn’t think it was a problem lol So anyway then they said they think it’s because it has the mid muffler delete.. and I bought the car like this from them as a certified preowned car . So fully under warranty and I know it’s not from the exhaust it’s definitely somthing in the motor.. any way now they think it’s the plugs they replaced them and that didn’t fix it .. now they are claiming it must be the exhaust so there goin to try to change the exhaust to fix it .. the thing is I’ve sat in 5 other scat packs and some with cut mufflers and those cars didn’t rough idle like mine does. I’ve had other ppl that own scats sit in my car one works in the sales at dodge and they say yeah that’s definitely not right .. and other mechanics also sat in it. And they say the same . There was one scat pack I sat in that was used and looked like it was abused and that car made the same noise as mine and it was bone stock no exhaust mods so it can’t be the exhaust that car just has the same motor problem mine does .. this car has 15,000 miles now and I think who had it before really beat it up .. it had to have the rear end replaced too . Well any way does anyone els notice that vibration when stoped ? Windows up ,ac off , radio off and really listen to it idle . Our car sounds like somthing has to be wrong the top service guy said it’s definitely concerning noise so we’ll see it’s been in 4 times for this issue and no one can figure it out.. I had to open a case on the car through Chrysler corporate it’s becoming this real nightmare . And driving crappy rentals sucks too lol
 

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2020 Dodge Challenger Hellraisin Scat Pack
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Misfires can be tricky. A cylinder can misfire off and on and that may not be considered a real "misfire". At least with some engines. It takes a number of consecutive misfires before the cylinder is considered be misfiring and this then lights up the CEL.

If the tech was observing the misfire counter that is used to tally up consecutive misfires prior to actually logging a misfire then one misfire is nothing.

And the way you describe the engine's behavior I would expect more than one cylinder and more than one misfire.

You don't mention the CEL was on and you don't offer any error codes that may have been pulled from the car. Absent a CEL and misfire error codes the engine controller has not encountered what is defined as a real misfire condition.

Rough engine running is quite subjective. However, based on what you posted the engine doesn't appear to be running with the normal amount of high performance roughness but something more than that which can signify a possible engine problem. Notwithstanding the apparent absence of a CEL and error codes. And you apparently have some Dodge employees in agreement with you.

If the car is being worked on under warranty you best let the dealer do what it thinks is necessary. If this means addressing the exhaust then so be it. I have encountered situations before -- fortunately not with any of my cars -- in which the engine is suspected of having a problem. The factory has a list of things to check even replace and only if these don't work does the factory then authorize repair or more often replacement of the engine. Not saying the engine in your car is going to end up being replaced.

My point is don't try to tell the dealer service department its job. The factory calls the shots. Not the dealer and certainly not you.

That the car has had the exhaust system mod'd raises in my mind the possibility the engine may have been modified. Even it hasn't been certainly there is the usage you suspect the previous owner gave the car. So who knows what will turn up to be the cause of the apparently abnormal level of engine roughness.
 

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Discussion Starter · #3 ·
Misfires can be tricky. A cylinder can misfire off and on and that may not be considered a real "misfire". At least with some engines. It takes a number of consecutive misfires before the cylinder is considered be misfiring and this then lights up the CEL.

If the tech was observing the misfire counter that is used to tally up consecutive misfires prior to actually logging a misfire then one misfire is nothing.

And the way you describe the engine's behavior I would expect more than one cylinder and more than one misfire.

You don't mention the CEL was on and you don't offer any error codes that may have been pulled from the car. Absent a CEL and misfire error codes the engine controller has not encountered what is defined as a real misfire condition.

Rough engine running is quite subjective. However, based on what you posted the engine doesn't appear to be running with the normal amount of high performance roughness but something more than that which can signify a possible engine problem. Notwithstanding the apparent absence of a CEL and error codes. And you apparently have some Dodge employees in agreement with you.

If the car is being worked on under warranty you best let the dealer do what it thinks is necessary. If this means addressing the exhaust then so be it. I have encountered situations before -- fortunately not with any of my cars -- in which the engine is suspected of having a problem. The factory has a list of things to check even replace and only if these don't work does the factory then authorize repair or more often replacement of the engine. Not saying the engine in your car is going to end up being replaced.

My point is don't try to tell the dealer service department its job. The factory calls the shots. Not the dealer and certainly not you.

That the car has had the exhaust system mod'd raises in my mind the possibility the engine may have been modified. Even it hasn't been certainly there is the usage you suspect the previous owner gave the car. So who knows what will turn up to be the cause of the apparently abnormal level of engine roughness.
that’s why I’m dealing with the Chrysler on this and there is no check engine light on but also I’m just seeing if anyone els had this issue because they keep telling me the cars is fine according to the computer and none of the mechanics can’t figure it out.. the misfire thing just has me wondering because it missed once on the lap top in about a minute of idle but could it be slightly missing and the computer isn’t registering it or somthing .. idk but for 5 thousand miles now the car has really rough feeling in the motor at idle and it gets worse if you romp on it a little and come back to an idle
 

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that’s why I’m dealing with the Chrysler on this and there is no check engine light on but also I’m just seeing if anyone els had this issue because they keep telling me the cars is fine according to the computer and none of the mechanics can’t figure it out.. the misfire thing just has me wondering because it missed once on the lap top in about a minute of idle but could it be slightly missing and the computer isn’t registering it or somthing .. idk but for 5 thousand miles now the car has really rough feeling in the motor at idle and it gets worse if you romp on it a little and come back to an idle
Rough running engine with no CEL and with good motor mounts is rare.

Might be of some value to view the accessory drive system using a strobe light to see if anything is wobbling or manifesting serious runout. There have been several reports -- can't remember if any involved a Scat Pack engine though -- of a crankshaft dampener failing and in at least one case coming off.

I hope you are successful in getting this sorted out to your satisfaction. Be sure to come back and update the cause.
 

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Discussion Starter · #5 ·
Rough running engine with no CEL and with good motor mounts is rare.

Might be of some value to view the accessory drive system using a strobe light to see if anything is wobbling or manifesting serious runout. There have been several reports -- can't remember if any involved a Scat Pack engine though -- of a crankshaft dampener failing and in at least one case coming off.

I hope you are successful in getting this sorted out to your satisfaction. Be sure to come back and update the cause.
I will let you know what they find. They are putting a stock exhaust on it tomorrow. We’ll see if the motor still runs rough . They said the noise is caused because there isn’t enough back pressure… we’ll see
 

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Not the AC compressor starting and stopping perhaps?

A Guy
 

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What year is the car? And you bought it used from a Dodge dealer? Maybe the guy did a cam swap, etc., and needed a tune to the PCM to get it to run right. Before he traded it in he may have removed the tune, because he didn't want the dealer to find it, ruining his chances to trade it in, so know it runs like dirt.
 
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