I have an 08 auto z.
Didn't notice it happening before, but recently, it has been happening.
When I start the car, doesnt matter if it is cold or not, the RPM shoots up to 2k and drops down to 500 and goes back up to 1.5k. Sometimes it drops so low, the engine almost stalls, but not quite. What is wrong with my car????

 

You need to list your mods. If no mods, take it to the dealer.

 

everyting stock

 

Hmm, weird. I have kinda the same problem, but it only started a week after I got my Test Pipes put in. And I only get this if the car has been sitting for like 8 hours.

I'll try to record a video of it tomorrow morning to post.

 

i wanna say its normal, cause my car used to do that..
with the exception of dropping too low...

mine just starts in the high 1600s, the drops to normal idle rpm.. its a manual though

 

hope its normal

 

Here is a video of what mine does. Once again, this is only on cold starts, when it's been sitting for about 8 hours.

http://www.youtube.com/watch?v=SvtcWDYbv3I

I did some research and a similar thing happens when the knock sensor has to be replaced. Could this be the problem?

 

Took it to the dealer
Waited about 5 hours and finally a guy came out saying "everything seems to be normal" ?!?! I told him it almost stalled 3 times already but they couldn't repeat the problem I was having ;;;

 

I recently had some issues with the knock sensor cable shorting out and I didn't have this problem.

Do you get any CEL errors?

I got a P0327. Fixing cable fixed it.

 

No, I didnt get any errors. no check engine light, dealer hooked it up to a computer to check its record, but they said it was clean. It seems to be worse when the car is warmed up. It drops down to 500 or so and shoots back up to around 1k. Dunno what to do