I have just completed an ITA 240sx and I am in need of a temporary fix for the Nissan Nanny speed limiter. I am not worried about the engine rev limiter at this time. The ECU is at JWT but it does not appear that it will be back to me in time for an event on March 14. I have been researching this for the past week and found the following methods so far. None seem to be definitive.

  • Cut pulse wire signal from speedometer to ECU.
  • Disconnect vehicle speed sensor from trans.
  • Disconnect 4th and 5th gear switches.
  • Replace manual trans ECU with auto trans ECU.
  • Install a potentiometer (reportable does not work because VSS sends an AC signal to speedo head that in turn digitizes it before sending to ECU).
  • Change the VSS gear to "lower" speed.

Car does not have a speedometer head. All outputs from trans are disconnected (VSS, 4th gear and 5th gear switches). It will still cutoff in high rev, WOT situations. The cutoff occurs well below the engine speed rev limiter, in the 4000 to 5000 range. I have also found that the ECU is suppose to be fool proof by going into cutoff if it does not see a speed signal for more than 4 sec at over 4000rpms (or some value near that). I have felt the cutoff a little in 3rd but mostly in 4th and 5th.

I am just trying to get some seat time and start sorting the car at a NASA event before going to SCCA drivers school. So I need it to just get around Road Atlanta without falling on it's front bumper. If anyone has any additional information or help, it would be greatly appreciated.
Thanks