What causes idle-hunting / surge?

[8000RPM]

When cold starting my NSX, the engine sometimes seems to hunt for the proper idle RPM as the tach needle oscillates up and down.

What are the potential causes for this type of behavior?

 

[Larry Bastanza]

It the car fine once it warms up? A nice steady idle?

This would typically indicate a small vacuum leak. There was another thread recently that discussed finding these. Go here: http://www.nsxprime.com/ubb/Forum10/HTML/000821.

Could also be a dirty throttle body. How many miles? last service?

HTH,
LarryB

 

[DanO]

Check the service manual at page 11-66. This documents the Idle Control System. It’s a rather complex system with lots of input variables. I’d look into the Fast Idle Valve and possible vacuum leaks as Larry suggested.

DanO