so i'm coming to the end of the parkway i reach the half mile sign and shift the car in to neautral, let off clutch and im going about 60mph. I notice the rpm needle is bounceing from around 800 up to around 1,400rpms than goes back down... than up...than down...up
it continues till i stop at light, i never noticed it before if its normal, or is a problem. I did do an oil change this moarning... any input would be helpfull

 

dude i noticed the same thing on saturday. freaked me out, but it looked like it calmed down after.. not sure what to think of it either..

 

Normal.

I forget what causes it, but it's not a problem.

 

dosent do it all the time though does it? i dont think it did it on my way to work yesterday.. and its alot more noticable for me cause i have an exhaust..

 

no... this is the first time i noticed it, mabye its nomal

 

Mine has never done this, and I dont know what would cause it to do so?

 

Yeah, mine will do that for a bit, then eventualy go back to idle RPMs. The only thing I can think of is that when you let of the gas completely at high RPMs, your flywheel will start to deccelerate. It will continue to do so until it reaches the point of idle, but since it is decellerating too quickly, it may go under idle. Sooo, maybe the engine will compensate by giving it a little gas shooting it up a bit too far again?

just my crazy ideas...

 

It happens more when you reset your CPU and I think it's part of the CPU learning/relearning sequence.... BUT, it's normal and nothing to worry about.

 

Mine does that about once a month or so. Not a big deal. I just take off and it is fine at the next light.

 

I've noticed that if you turn off your HVAC, it bounces less while coasting. Anyone confirm this?

 

i could be the car using a little more power using the accessories like power steering or a/c

 

Since we are Drive by wire, pressing on the gas pedal does not directly open the throttle body. Instead, it sends a "request for torque" to the ECU, which moderates the opening of the TB, addition of fuel, etc.

Running the A/C requires power from the motor, so this could be the ECU increasing the idle power output to compensate for the increased drag. Combine that with whatever power steering, braking, and electrical demands at that time, and this would add up enough to trigger the ECU to deliver a little more engine torque.

You wouldn't notice this at any RPM above idle, since at that point, the motor's making power to push the car forward. All of the accessory demands have to be satisfied first before forward acceleration can happen.

(Just a theory.)