94 pcm, 93 T56 3.36 2.07 1.35 1.00 0.80 0.62
3.73 gear, 315/35/17 rear tires
when I set the parameters with Tuner Cat my speedo rides about 6 mph high
just wundering if anybody else has had this issue and what their set would be

 

Deleted this entry about T56 gearing, didn't have my head screwed on when I answered this.. Bob D.

 

The internal gear ratio's wont make one bit of difference with the speedo since the speedo gear is mounted to the output shaft and measures driveshaft revolution.

So, the only thing that might throw that off is if the output shaft ring/sensor combo is different than other years.. I dont know if they are or arent.

Also, I did have a problem with my speedo as well but ut was more like 1/2 actual speed or something like that.. whatever I did in the settings it didnt change it.. I had to revert back to the pre-speedo problem LT1 file then re-apply the speedo settings along with all other engine parameters and since then it's been fine.

There is a warning in LT1 Edit about that in the speedo section.. guess sometimes it just gets messed up.

If you cant figure it out then try switching back to an untouched LT1 file.

 

I was told that the 94 pcm can't or does not understand the lower gear ratio of the 93 T56 that is what I am asking if anybody had to put different parameters in to get the pcm to display speedo readings right

 

The PCM has no way to know the various gear ratios.... and it doesn't care. Its only interested in reading the reluctor gear on the output shaft. You need to find out if the 93 reluctor gear puts out more pulses per output shaft revolution than the 94+ T56 (16 pulses per output shaft revolution).

Is your speedo ALWAYS 6 mph higher than actual speed, no matter what speed you are going? That would indicate a problem with the needle orientation. If there is a "pulse" problem, the difference between the indicated speed and the actual speed would be a fixed percentage of actual speed, not a fixed number of miles per hour.

 

As stated above if your error is a percentage in all speeds then you can check the " TunerCat - Tools - Speedometer Calibration -' Pulses per Driveshaft Rev box ". Since you have the wide ratio T56 it looks like yours should be set to 11. If your error is a fixed MPH at all speeds then this does not apply.

 

thanks you 2,I was not sure were to start on the correction this guide me in the right direction