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  • Auto Trans Issue

    I have been autocrossing a stock '96 s14 with an auto trans for the past three seasons [yes, I know ]. Long story short, I have started to experience random downshifts from 2nd to 1st when entering/exiting slow speed turns on course. The transmission downshifts into 1st under braking and upon exit the car accelerates thru the RPM range, as strong as a KA is able to, upshifts into 2nd, but then randomly kicks back into 1st under full throttle at about 3-4k in 2nd gear [wonderful experience]. When this happens it remains stuck in 1st until I get back to pit and turn off the car.

    At the last event, where this happened on back to back days at the same corner, engine temps were only slightly hotter than normal, but definitely under the mid point on the gauge. The car typically runs 25-40% between cold and hot. Trans fluid was fresh, pink with no odor at operating capacity. All other fluids, etc. good as well. The O/D light began flashing much longer than normal on startup before each remaining run after the excursion.

    At that point I had had a CEL for a while which I assumed was the EVAP canister, from a while back, but was not. I checked the codes and the speed sensor came up. I cleared the code, found where some wonderful mechanic installed the speed sensor with what appeared to be some SAE bolt. I was able to clean up the threads and get a metric bolt to thread nicely. I have since installed a new Nissan speed sensor in the car, but am concerned that I am missing something. It just seems too easy. I have driven it for almost 300 miles since clearing the code with no issues, CEL or O/D light - granted this was not under the same loads as auto-x.

    The car has just a little over 93k original miles and drives, shifts, engages gear and operates with no issues other than the random downshift.

    I have read so many things on the internet that my head is spinning. Has anyone had this issue or have any insight for additional troubleshooting? I have searched through the FSM and cannot seem to find a reasonable path to follow.

    Thanks in advance and yes I have a 5-speed swap collecting dust in the garage
    '96 s14 SE - stock format, 90k, two-pedal torture

  • #2
    Originally posted by diggles240 View Post
    I have been autocrossing a stock '96 s14 with an auto trans for the past three seasons [yes, I know ]. Long story short, I have started to experience random downshifts from 2nd to 1st when entering/exiting slow speed turns on course. The transmission downshifts into 1st under braking and upon exit the car accelerates thru the RPM range, as strong as a KA is able to, upshifts into 2nd, but then randomly kicks back into 1st under full throttle at about 3-4k in 2nd gear [wonderful experience]. When this happens it remains stuck in 1st until I get back to pit and turn off the car.

    At the last event, where this happened on back to back days at the same corner, engine temps were only slightly hotter than normal, but definitely under the mid point on the gauge. The car typically runs 25-40% between cold and hot. Trans fluid was fresh, pink with no odor at operating capacity. All other fluids, etc. good as well. The O/D light began flashing much longer than normal on startup before each remaining run after the excursion.

    At that point I had had a CEL for a while which I assumed was the EVAP canister, from a while back, but was not. I checked the codes and the speed sensor came up. I cleared the code, found where some wonderful mechanic installed the speed sensor with what appeared to be some SAE bolt. I was able to clean up the threads and get a metric bolt to thread nicely. I have since installed a new Nissan speed sensor in the car, but am concerned that I am missing something. It just seems too easy. I have driven it for almost 300 miles since clearing the code with no issues, CEL or O/D light - granted this was not under the same loads as auto-x.

    The car has just a little over 93k original miles and drives, shifts, engages gear and operates with no issues other than the random downshift.

    I have read so many things on the internet that my head is spinning. Has anyone had this issue or have any insight for additional troubleshooting? I have searched through the FSM and cannot seem to find a reasonable path to follow.

    Thanks in advance and yes I have a 5-speed swap collecting dust in the garage
    Do you have a boat? Use the auto as its anchor and put in that 5 speed already!
    Core4 Motorsports
    CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
    S14 VQ AER Endurance Racing Team

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    • #3
      Originally posted by gills View Post
      Do you have a boat? Use the auto as its anchor and put in that 5 speed already!
      This!!

      This is a quick read and interpretation, but it sounds like you have a fluid line pressure issue. I had a similar problem yeeears ago on and old automatic Maxima when I thought it was cool to disconnect the dropping resistor and drive around chirping shifts into 2nd and 3rd. after a while, I started having problems with the thing shifting out of O/D and into 3rd at highway speeds, and the CEL would start to flash, indicating trans line pressures were too high.

      reconnecting the dropping resistor fixed the problem for me..

      BUT.. that was a 3rd/4th gear at 80+mph. your situation sounds similar, except that it's happening in 1/2 at autox speeds.. This could be a line pressure or a dropping resistor problem.
      Originally posted by SoSideways
      I don't care what color they are as long as they are LONG AND HARD.
      '04 G35 Sedan 6MT- The DD
      '96 240SX- The Track Toy

      Comment


      • #4
        No issues so far after the last event and 26 runs + 3.5hr drive each way. Fingers crossed

        We shall see how this plays out.

        I know the auto-box needs to be used as a boat anchor...
        '96 s14 SE - stock format, 90k, two-pedal torture

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