Hello I’ve been having this problem for months now, my car (08 g37)gets into a certain evil mode where my idle will just keep climbing to 1000rmp and then when I downshift it waits til last second to go into first then it surges me forward at a stop (most of the time) sometimes my car runs fine. I took it to Nissan and Infiniti to see if they could update/reprogram my ecu and they both said they could find anything to update it to. So it couldn’t possible be the TSB that describes the problems I’m having which the solution is to reprogram your ecu.

It’s driving me insane, I’ve done relearns many times, I’ve checked for vacuum leaks and everything, my rpm goes up if I press the break pedal and stays up for a while then drops, it also struggles to go below 1000rpm as shown:

when driving normally in P my idle is around 650 but reaches up to 1000 when driving around for a while

https://youtube.com/shorts/HTjdRCFg0jQ?feature=share

 

If any of the following are true:

a) When coming to a full stop (stop sign/ red light) the car lurches forward as it downshifts;
b) In PARK, the idle "hovers" around 1000RPM;
c) In DRIVE, the idle "hovers" around 1000RPM requiring more brake pedal pressure to hold the car; and/or
d) Everything returns to "normal" after a restart only for the issue(s) to present again- eventually,

then I strongly suggest you download/ print a copy of the ITB (pdf attached) and bring it to the dealership and require them to apply the update.

See this post as it explains the issue I had. Initially, the dealer didn't want to apply the update saying "they can't repeat the issue but we'll replace this, that, and the other." I had a copy of the ITB in-hand, and with more "fussing" and a test drive with the tech, finally, they agreed to the update. To this date, the car idles flawlessly at 625-650RPM years later.