Hey guys so I have an 06 g35 coupe with 6mt. Earlier this week I noticed that when I press on the clutch after I've let off the throttle that my rpms increase. It also stays pretty high when I'm at idle. While this is happening I'm also loosing a ton of hp. Almost feels like the car goes Into limp mode. This doesn't happen every day but so far this week it's happened about 4 times. The car usually idles at 900 rpms. When the rpms increases it jumps up to about 2000 and slowly goes down to 1000 and stays there. Can anyone help???

 

RPM increase/drop with the clutch pedal is normal to a degree, there is a load from the input shaft of the transmission but it should immediately compensate so the rpm's don't fluctuate more than about +/- 50 rpm or so. I would start by checking all vacuum lines and the intake tract for a small leak, ecu reset, idle air reset.

http://www.nicoclub.com/archives/g35...procedure.html

Use a timer, the seconds count needs to be VERY precise.