Hello everyone, New to the site and have a problem with a tranny. I have a 96 with an automatic. did a service and found oil and screen to be clean with no sludge in the pan. When cold, it delays the first shift, when it warms up and you leave slowly from a stop it hits 1st, 2nd,3rd and 4th pretty smoothly. if i accelerate a little faster it seems to stay in second briefly then jumps right to 3rd and around 40 mph it hits overdrive. I have replaced the Vacuum modulator and it seems to be the same. What am I missing

 

a 5 speed manual











Left yourself open, but I have no other suggestions

 

No its an Automatic

 

Make sure you have used the exact formulation of trans fluid called for in the manual. There are differences between some of the Dextron numbers that cause them to shift differently.

 

I have used the recommended fluid with no difference. I was told the modulators come pre adjusted, but wonder if it needs to be tweeked alittle. I have not seen any kind of kick down cable either

 

I am rather unfamiliar with the automatic transmissions in our cars so I am of little assistance. I believe it may be made by Aisin for Mazda. I bet if you coulld find a Miata Factory Service Manual (FSM) it would contain diagnostic and adjustment procedures.

Outside of that, Googling symptoms may prove useful. Remember, there may be front wheel drive variants of that transmission in other brands and models of car so symptoms are more important than fitment.

 

Your transmission is a Jatco 4N71B. Originally made by and used in many Nissans. I have a '97 with the same tranny, and what you describe is normal. There are shops, such as levelten.com who modify and put insane amounts of horsepressure through these automatics. Stock, or slightly modified engines will not overpower your transmission. Embrace the transmission for what it is. Throttle to the floor the Tranny will usually give crisp upshifts at 6500rpm. The shift to 4th. will always come late when your tranny is cold, by design, according to Jatco.Let it come up to operating temperature normally, and then drive it as you wish. You could also check some of the early Z-Car sites for info as many earlier Nissan V6s ran turbos with an automaticstraight from the factory.