i have a 2014 sentra with the jatco cvt transmission that is slipping taking off. the customer took the vehicle to another shop and based on the codes that were set they said it needed an new transmission. he towed it to my shop and it drove fine off the wrecker and into the shop. i pulled the trans pan adn found some fine metal on the magnets which appeared to be normal per the nissan service bulliten i read and looked at the photos and compared mine to. i removed and tore down the transmission and found the flow control valve in tjhe pump to be stuck so bad you couldnt pry it out. i think this is a known issue with these pumps. i replaced it and the seal, and orings also replaced the clutches even though they looked fine. i went thru both variator pulleys and replaced the seals and inspected the push belt. all looked fine. i replaced two brearings on the pulleys that were noisey. reinstalled the trans and had the same issue. when cold it drives normally until about 110 degrees farenheit fluid temp and then the trans slips and the throttle is very unresponsive, only gets about 15% throttle angle at wide open throttle. also noted the target pulley ratio went from 2.2 when it was operating normally to .5-1.0 when it is acting up. if i shut the car off for one second it will pull fine and throttle fine for a few yards then it seems to go into limp mode again.
removed the trans again and went thru making sure all seals were ok and not cut, air checked all three clutches and variator pulleys. all appear ok. replaced the valve body with a reman unit with new solenoids and had another jatco cvt out of a chevy spark that i know was good and swapped out the pulleys and push belt as they looked brand new and air checked great. reinstalled unit and have same issue.
some things i noticed on the scan tool data was that the vehicle speed in the tcm was working normally but the VSP reads 0 all the time. the input , secondary and output sensors all read correctly. i tried a different scan tool and the VSp still reads 0 mph all the time. there are no codes set in any modules. i also swapped out the tcm with a used one ( i didnt program it as i dont have access to be able to program nissan) i did the erase and reset calibration values. still have the same issue. one thing i noticed in the ecm data was the ASCD vehicle speed sensor always reads 14 mph ( not sure what this data is but it looked wrong). it seems like the transmission is in limp mode or something. i heard the taillamps could have moisture in them causing this so i unplugged both harness going to the taillamps and still have concern.
when it is cold up to 110 degrees it shifts beautifully but seems like something is going on electrically causing my issue. if anyone has any ideas where to look it would be greatly appreciated as im running out of ideas. thanks for any help