I am having a new problem with the A/T on my 04 G35. When I decelerate, there is a studder or jump at 25 mph. It feels like the brakes are engaging harder for a brief second before it reduces. I feels similar to when to torque converter causes the car to slightly studder but that is usually at asteady 40 mph, but this is only during braking.

At first I thought it might be the brakes, but this is always at 25 mph and it doesn't seem to matter how much the brakes are pressed, just that the car is decelerating through this speed. I am suspecting the A/T is having a hard time shifting from 3 to 2. Going to check the fluid tomorrow and make sure that it happens with the traction control off. The car has 145K on it and it has been 50K since the last trans flush, so it probably due a trip to the Nissan or Infiniti dealership. There is no other trans slipping or brake issues.

Anyone else with an A/T that has a rough downshift from 3 to 2?

 

With traction control on it still made the jump during deceleration.

No jump in manual mode unless I manually downshifted. It booted me from manual mode after decelerating twice and even though the shifter was still in manual mode, it wouldn't respond. I will see if it lets me go into manual mode after it is restarted, but it didn't look promising.

I didn't realize that I needed a wrench to get to the trans fluid dipstick, so I haven't check it. After reading about the problems with trans flushes, I will just shoot for a fluid change.

 

You may have a sticking valve in the valve body of your transmission. This slight "flare" that you are experiencing while decel/braking/vehicle down-shift may be due to the extra pressure being generated to actually open the valve. This causes a slight spike in the pressure/volume of ATF moving through the valve, that it causes your down-shift/decel to be a bit harsh.

Just my 2 cents...