speed sensor

[jhanner]

i got a chance to try it out this morning and it worked great, it shifts right and showing the speed almost dead on. i really apreciate all of your help

[Taz]

Great to hear it worked. Sometimes I get so focused on entering precise data for the PCM to work with, that I forget to use my own brain !

When you mechanically calibrate your cable driven speedometer (drive & driven gears), it should cause the pulse generator to output 8K pulses per mile – if the mechanical calibration is accurate.

The solution ended up being painfully simple – set pulses per mile (H0101) to 8000. This can’t be done directly, so I left your tire diameter at 38 inches (needed to use 37.99), and adjusted the final drive ratio (H0103) until the calculated value of H0101 was 8000 pulses per mile (or 4971 pulses per Km).

On previous tunes, where various gear and tire values had been entered, had caused the software to “calibrate” the speedometer a second time – after you had already done this mechanically.

The current tune values for H0101 through to H0106 should never be changed or updated – for as long as you use the 8K pulse generator. Future changes to gear ratio / tire diameter must be calibrated mechanically by changing the drive and / or driven gears that turn the speedometer cable.

You can still use the Shift Point Correction function (to make global changes to transmission shift values) - but only if you enter a percentage – do not alter tire diameter or diff ratio values as shown.

I still learn something almost every day !!


Regards,
Taz