Hey everyone.. I got a 2003 G35 with only 70k miles.. I bought it off my brother.. The weird thing is 1st and 2nd gears jerk/slip pretty hard. And the rest of the gears switch great.. So if I'm driving in the city with a lot of stop and go driving it gets so annoying with 1st and 2nd jerking.. If its freeway its as if nothing is wrong.. My question is what can this be.. The other thing I need to mention.. My brother owned it before me.. The same problem with the tranny. So he bought a tranny with only 20k miles and put it in.. And it does exactly the same exact jerking and slipping in 1st and 2nd gear.. A friend of his told him if you change trany you also have to change the torque converter or it will do this.. Is that true about the torque converter?

 

Just to verify you are talking about the 5AT correct? Just want to make sure, no you don't need to swap the torque converter unless there's something wrong with it. Since the transmission has been changed but the problem still exists with the same torque converter then the original transmission was probably fine but the torque converter was bad and never replaced.

Typically you can spin the inner shaft by hand and feel if something is wrong unless it has eroded vanes from hard driving with super contaminated fluid.

Describe in more detail exactly what you mean by "jerking and slipping" the rpm's climb but the car isn't going any faster yes? Then suddenly the vehicle jerks forward quickly, rather than being a linear power delivery it feels like an on/off switch?

If so that's usually an indication of low fluid, do you know how to properly check AT fluid level and has it been done recently?

This can also happen if you use the wrong fluid, hydraulic fluid lubricates all the wet clutch packs between the sun gears and if you don't use the correct fluid (only use Nissan Matic-J or Matic-S) then you change the friction coefficient of the fluid and you can get either harsh or sluggish engagement.

All these things are more prevalent at lower gears because of the torque multiplicative effect of the high gear ratios.