I bought an used 2011 G37X sedan couple months ago. The car is great, expect when it is at low speed @40kmh (~20mph). When I am slowing down, the car will "chock" @ 40kmh (like downshift too early when driving a manual). It doesn't matter if I brake hard or gently.

Any ideas? Is it related to the ITB12-027?

TIA.

 

Do you drive in DS? If so that is normal it's designed to down shift that way to help slow the car down. If you drive in D it should be a lot smoother if it does downshift my car doesn't seem to downshift much at all in D.

 

what are your rev's jumping to when it happens?

If its not redlining it may just be the characteristic of the vehicle that you aren't used to. the car will learn your style of driving after a few hundred miles and may smooth out.

If you are really concerned and that's all it is, there is a way to "clear" the shift memory and have it start learning right away. look at the DIY's on cleaning throttle bodies and the associated links for when you screw it up and need an ecu reset...(thats when I needed to do it)

also I would second what the above poster wrote, you may just be in DS

 

No, I wasn't driving in DS mode.