rb25det speedo calibration

[250sxGTST]

im sorry if this was answered but i couldnt find anything on this exact topic. I have an r33 rb25 in an s13. my speedo has been off (about half) since i did the swap and i figured it was in the cluster calibration. I recently installed the power fc and watched the speed in km/h on the display and it reads the same as my cluster. i might be missing something here but i have an r33 trans wired to an r33 power fc shouldnt the speed reading km/h be somewhat close to the actual km/h that im actually traveling. the only difference between the s13 and the skyline is rear gear and tire size. does the r33 gtst run some ridiculous gear in it that my speed is no where close. the r33 would have to have a 6 something rear gear to my 4.1 to be off as much as it is. im gonna eventually purchase the calibrated cluster but i was somewhat surprised that the power fc didnt read the correct speed. thanx for any insight into this

[Darius]

The Power FC like your stock ECU gets it's speed reading from the cluster. It goes speed sensor > cluster > ECU. If you wanted to calibrate your speed to your cluster you would have to do so on the input wire to the cluster.

[gawdzilla]

The Power FC like your stock ECU gets it's speed reading from the cluster. It goes speed sensor > cluster > ECU. If you wanted to calibrate your speed to your cluster you would have to do so on the input wire to the cluster.

thats interesting that the 25 does that. the 26 ecu takes the speed sensor reading directly, so it doesn't care what your speedo is showing. i wonder why nissan did it like that.

[David_NISMO]

thats interesting that the 25 does that. the 26 ecu takes the speed sensor reading directly, so it doesn't care what your speedo is showing. i wonder why nissan did it like that.

Don't know why, it doesn't need it, people cut that wire (pin 53 I think?) all the time to prevent speed limiting.

[Darius]

yeah mine is cut already, but I was planning to cut it originally. There's another thread running that I posted a speed signal modifier and tach signal modifier. Tach signal comes from the ECU though (pin #7). Check it out for more details.