Hey i just did a 5 speed swap on my 240sx and it runs great except that when im in 3rd gear around 5200 rpms the rpms just drop so i have to put it in nuetral and then put it back in gear it does the same in 4th around 4500rpms and in 5th at 3800 rpms does anybody know what it can be please any help is aprreciated i never put a tranny harness in it so i dont know how fast im going and i beleive its still a automatic ecu but im not sure cause it was also having shifting problems when i had the automatic transmission it just wouldnt go into overdrive..

 

your best bet is to check for codes and get back to us with the results. but if you want i can take a stab at it with the few details and background information you've provided. i'm thinking your timing is off or you're tps is faulty, it's just a guess though so i could be wrong.

 

It sounds like it could be the tps. did you replace it with a manual sensor? I would recommend getting a manual ecu as well.