'91 300zx N/A 2+2 will not shift under 4k!!!

[Speedahulic]

hello and to start off I just swaped a j30 into the car and got it running but it will not shift under 4K?!? I got the car for my son with a locked up stock vg3 engine (dumbass kid dropped a screw in the injector hole while changing injectors i was told)... after swapping the charging system harness pretty much all else hooked right up and runs very nice and smooth...supposedly has a tuned ecu not sure if it does or not but the trans WILL NOT shift under 4K...any ideas where to start trouble shooting this problem or could it possibly be the tune on the ecu? seems to slip a small amount when it does shift but once in high gear every thing seems fine...at low speeds it does not seem to catch until 2500 RPM then shifts at 4K...turning on and off the O/D made very little difference but seemed to lock up the converter as i would assume is correctly... any suggestions?

[nissanfreak12]

The Throttle Position Sensor controls the shift points of the transmission. try adjusting the TPS and see if that helps. Flush the transmission and put new fluid and a new filter, that may also help. Transmission has its own computer, so a tuned ECU should have no effect unless someone messed with it and put in a 5 speed ecu, or changed the parameters to make it a 5 speed.

Have you checked for code in the ECU

[Speedahulic]

I will check and adjust accordingly the TPS...I have not tried pulling any codes yet....just got it running late yesterday and only had time for a short test drive...the ecu was in the car when I bought it and also the auto trans. I just replaced with a j30 and used the original ecu that is supposedly tuned. The j30 came out a 5 speed car n have that ecu as well but am not using due to it being for a 5 speed.

[nissanfreak12]

Yeah, the engine being from a 5 speed should have no effect on whether it shifts odd in these cars. The only other thing is either he car sat for period of time and the solenoid is just sticking or there were issues before selling to you. Maybe driving it around will maybe make it better. I wouldn't bet the ECU is actually tuned, since it being an NA and an auto. Normally if they are they will have some marking they are,mainly by the company that tuned them and how they were tune ie, injector size, single pop, exhaust, etc...

[Speedahulic]

adjusted the TPS and car runs super smooth with nice clean 7-800 rpm idle...no real change in the shifting also noticed after driving a little to see if the solenoid might unstick that it will not kick down...have to manually drop the selector for it to happen...any ideas?