[DanielM]

So I’ve had the car for about 10 months and recently got it back from the shop after installing a 1 piece aluminum driveshaft. (The carrier bearing in the middle failed on the stock one) Before I installed the driveshaft I noticed a slight shake at idle but didn’t think much of it. Now after installing the driveshaft and rear cradle bushings the car seems to shake and bump more at idle and it’s way more noticeable.

(car has 65k miles)
2016 charger Hellcat

 

[baabootoo]

Did you add that other piece they recommend with a one-piece driveshaft to warranty it? I can't remember the name of it. Either way, that shouldn't affect idle quality at a standstill.

 

[Rockster]

So I’ve had the car for about 10 months and recently got it back from the shop after installing a 1 piece aluminum driveshaft. (The carrier bearing in the middle failed on the stock one) Before I installed the driveshaft I noticed a slight shake at idle but didn’t think much of it. Now after installing the driveshaft and rear cradle bushings the car seems to shake and bump more at idle and it’s way more noticeable.

(car has 65k miles)
2016 charger Hellcat

My first thought was the driveshaft install required a motor mount be loosened and this disturbance of the mount accounts for the increase in shake.

But I would be surprised if a motor mount required any loosening for a driveshaft R&R. Best I can offer is check the motor mount fasteners for any signs of wrenching. Check the transmission mount fasteners, too.

You do mention you noticed a slight shake at idle before. Could be it was an early sign of a problem that has gotten worse now to the point it is more noticeable.

I take it the CEL is not on? Wonder if there are any pending OBD2 error codes...

If you had the car in the shop a while -- some days -- the battery could be low. Or being used and a 2016 the battery could just be going bad. Be sure you check the battery cable connections are tight.

There is too the question of how well maintained the car is. Are all the wear/replaceable engine items good? I'm talking about the engine air filter, plugs, accessory drive/serpentine drive/supercharger drive belts.

In some cases each coil can be removed while still connected to the wiring harness and a check made for a spark arcing from someplace on the coil. A good coil shouldn't do that.

I'm not qualified even if I was at the car to advise you if the car was driveable or not. If the shake isn't too bad I'd be tempted to try some fuel system cleaner. I have used Techron in the past (with other engines) with good results. Techron via filling the gas tank with Chevron Supreme (with Techron) or adding a bottle of Techron.

My experience though is with turbocharged/supercharged engines (this included my Hellcat) engine fueling is pretty darn good and at least at just under 30K miles the engine doesn't appear to develop any deposits that require Techron.

But your car has 65K miles. So maybe...

 

[DanielM]

My first thought was the driveshaft install required a motor mount be loosened and this disturbance of the mount accounts for the increase in shake.

But I would be surprised if a motor mount required any loosening for a driveshaft R&R. Best I can offer is check the motor mount fasteners for any signs of wrenching. Check the transmission mount fasteners, too.

You do mention you noticed a slight shake at idle before. Could be it was an early sign of a problem that has gotten worse now to the point it is more noticeable.

I take it the CEL is not on? Wonder if there are any pending OBD2 error codes...

If you had the car in the shop a while -- some days -- the battery could be low. Or being used and a 2016 the battery could just be going bad. Be sure you check the battery cable connections are tight.

There is too the question of how well maintained the car is. Are all the wear/replaceable engine items good? I'm talking about the engine air filter, plugs, accessory drive/serpentine drive/supercharger drive belts.

In some cases each coil can be removed while still connected to the wiring harness and a check made for a spark arcing from someplace on the coil. A good coil shouldn't do that.

I'm not qualified even if I was at the car to advise you if the car was driveable or not. If the shake isn't too bad I'd be tempted to try some fuel system cleaner. I have used Techron in the past (with other engines) with good results. Techron via filling the gas tank with Chevron Supreme (with Techron) or adding a bottle of Techron.

My experience though is with turbocharged/supercharged engines (this included my Hellcat) engine fueling is pretty darn good and at least at just under 30K miles the engine doesn't appear to develop any deposits that require Techron.

But your car has 65K miles. So maybe...

The check engine light is not one but it did come on once for a misfire. I reset it and waited to see if it would come on again, so far it hasn’t. Also the car was parked at the shop for around 3 months. Also the idle shake doesn’t happen every single time its a on and off type of thing

 

[Rockster]

The check engine light is not one but it did come on once for a misfire. I reset it and waited to see if it would come on again, so far it hasn’t. Also the car was parked at the shop for around 3 months. Also the idle shake doesn’t happen every single time its a on and off type of thing

Car parked 3 months at the shop almost certainly the battery was allowed to run down, probably more than once. While the battery can be recharged the drain down degrades the battery.

And maybe mice/rats being at the car's wiring.

And 3 month old gas...

You may be faced with replacing the battery and then as soon as you can top up the fuel tank with fresh premium gasoline. If you have gone through what I assume is stale gasoline a dose of fuel system cleaner might be warranted. I'd do it. The cost of the stuff is low enough if it doesn't help no big deal.

'course, if the behavior gets worse or the CEL comes on probably time to stop driving the car and get it in for diagnosis.

 

[Reaperhwk]

Misfire. Find out which cylinder by getting a scanner that can pull the misfire counts. Most likely bad plug or possibly coil.
Random misfire will not always set a engine light because the computer needs to read so many counts in a certain time window to set a light.

I would have never cleared that code it would have told you which cylinder it is.