Thread: Mild shuddering / shake at Idle

Guys and Gals,

I have an 08 grand prix base model with 97k on the clock. I have been bothered by this assumed problem since I bought my car at 30k miles. When idling in park or neutral, the car will have an intermittent shake or shudder that can be felt through my butt on the seat and or the steering wheel. For the past couple of years I've assumed it was engine related since the motor moves around a bit at idle and thought it was just transmitting that movement through the car. I've maintained the vehicle as best I can and have done regular maintenance - and in an attempt to fix the shudder I did new plugs, wires, MAF cleaning, throttle body cleaning, pcv valve replacement within the last 15k miles. None of those made a noticeable difference to this issue . Overall the car runs great and has never had any dummy lights on, not started, etc.

The other day I realized that the tailpipe, and likely the hole exhaust system, was just vibrating at idle and was curious if this could be part of the problem. I am curious if anyone has any insight into this issue? Even more generally, should this engine feel like a sewing machine at idle or does the engine move around a bit at idle?

Thanks to anyone that can help!

-Joe

Ok, maybe I should clarify a bit. What I'm feeling is more similar to a singular bump vs a 2 or 3 second vibration. It's like someone softly kicking your seat - just one bump at a time.

Sometimes when I'm stopped in in gear and have the heater or A/C on I will get a vibration but I think that has to due with lots of draw on the electrical system. Not sure if that is what you are getting SomeDudeAtHome... that doesn't bother me as much because it goes away as soon as I turn off the fan.