I just recently joined the elite srt fraternity about a week ago when i bought my silver. Seeing as I am a perfectionist when it comes to my cars (as i know you all are), i noticed a few things and have a few questions.

When I city driving and i reach a stop light, my car slightly vibrates (more than i would expect normal, but not too bad) while i am stopped. When i let go of the brake, it kinda rolls with the vibrations as well.

Another issue is when im driving in traffic, after accelerating normally, when i let my foot off the gas, i feel like the car/engine is slowing itself down a little more aggresively than it should.

Now, one thing to note, this is all on my first tank of gas...which i accidentally put 89 grade into it. I know its supposed to be premium 91 and ill never mess up again, but i want to know if maybe this is whats causing the above problems, or also if this is really bad that i did that.

sorry if these are dumb questions, but better safe than sorry.

Update: put premium gas in it, still feeling the vibrations...is this normal? or am i the only one?

Need more information on the vibration. This is a relatively big cammed, performance engine and it will shake things a little more than you might be used to when idling. However, with modern fuel injection, it's nothing like the big cammed, carburetored cars. Describe the vibration in more detail.

Also, being newly assembled, clearances inside the engine will be tight until it breaks in some more. This will cause the engine speed to slow a little quicker than normal when you let off of the throttle. Keep in mind, though, that again, a performance engine has higher compression than run-of-the-mill engines and will decelerate much quicker. And, that's a good thing.

This higher compression is why we need the higher octane. Remember, don't cross the streams (Ghostbusters) and don't put 89 octane in your Jeep anymore. It can lead to detonation which is hard on the pistons, rings and rod bearings. Also, if the computer detects detonation, it retards the spark trying to stop it and that causes less power. On the other hand, no detonation means the computer advances the spark (but only to the maximum point that the car is tuned to) making optimal power.

Hope this helped.

i feel bad for all of yall that dont have access to 93 octane gas like i do here in Mississippi

Mine vibrates also. The inside rear view mirror is blurry when you are sitting at idle. Sounds like a general design issue we are going to have to put up with.

The engine feels like it is aggressively slowing down due to compression braking. The torque convertor is locked up and when you slow the transmission aggressively downshifts. Since the locked TQ means that engine and tires are directly connected you get compression braking from the engine.

Lower octane gas should probably just cause the ECU to hear detonation and remove timing in order to protect the engine - the result of which the truck will be slower.

hard to explain the vibrations, but phoenix seems to be getting the same thing.

when i am at a stop light, it feels like normal idling vibrations, only a little more intense (which may be because of the monstrous engine)

then, when i slightly let off the brake, and begin a very slow roll, those afore mentioned vibrations cause the car to slightly stutter while it is slowly rolling. if i go any faster than that (like completely take my foot off the brake), i no longer feel them.

thanks for all your help

hard to explain the vibrations, but phoenix seems to be getting the same thing.

when i am at a stop light, it feels like normal idling vibrations, only a little more intense (which may be because of the monstrous engine)

then, when i slightly let off the brake, and begin a very slow roll, those afore mentioned vibrations cause the car to slightly stutter while it is slowly rolling. if i go any faster than that (like completely take my foot off the brake), i no longer feel them.

thanks for all your helpIt's the 6.1 Hemi quivering in anticipation of being unleashed upon an unsuspecting world at any moment. Perfectly normal, mine has done it a little since day one.

ahhhh, that makes me feel much better

...when i am at a stop light, it feels like normal idling vibrations, only a little more intense (which may be because of the monstrous engine)
Exactly how steady is the tach needle during the vibration?

pretty steady from what i recall

Exactly how steady is the tach needle during the vibration?No movement at all.

It could just be the monster cam in these engines. Gasping for air.