Short story/question:

would would cause the auto in my 06 g35 to lurch forward violently in gear at idle?


Long story/background:

I built a motor, and got a higher stall tq converter for my auto. Trans already had the transgo valve body upgrade in it. Torqued everything down and started it, fired right up no issues, no leaks. developed a rattle at idle and a couple leaks a couple hundred miles later. the rattle turned out to be the torque converter bolts working themselves loose (and i know i torqued them to the torque listed in the FSM), which i think caused vibrations that led to the leaks. anyway, 1000 miles now on the motor, had a shop tighten the bolts, noise went away. then had them fix the leaks, upper oil pan and rear main seal. also had them do the transmission pan as well since they were under there as it was also leaking. got the leaks fixed, so pick up the car. get less than a mile down the street and am at a stop light in gear at idle engine speed. all of a sudden, the car starts lurching forward repeatedly. i am pushing as hard as i can on the brake so i dont hit the car in front of me. the only way i got it to stop, was to put it in neutral. once you get past a certain rpm, the lurching disappears, probably anything over 1.5k or 2k rpm, so issue is only in the lower rpm. no ses light, shop says everything went back together the way it was supposed to. i never had this lurching problem before they had the car.

any ideas on what this could be?

 

bump

 

anyone?

 

In for curiosity after reading, hope someone gives ya an answer

 

Torque converter was locking up when it shouldn't have been. Trans needed a rebuild.