Why does my car engine rev up and down when in park?

Answer 1

The idle valve is probably stuck. It probably needs to be changed. ----------------------------------- This may also indicate a vacuum air leak. My Odyssey did this recently. The idle and all other vacuum systems are connected. If one leaks, the idle may be effected. Question: Is your TCS light coming on and check engine light coming on? I used my TCS when it snowed last, and it started doing this right after (revving up and down). The TCS is a vacuum engaged system. Mine was stuck between on and off... probably because it is not used often. I fixed it! Simply put the vehicle in drive and burned a little rubber. The extra tork on the drive train disengaged the TCS completely and the problem immediately went away. Many part stores such as Advance have code checkers also. You can use one for free at many stores. You can clear your codes if your engine light is stuck on - to make it go off once it is fixed. Hope this helps someone, Marc