<all> home dyno kit??

[Ludis Langens]

"Mike Pitts" <mpitts at emi.net> wrote:
> I should be able to 
> get between 128 and 256 samples per second interrogating just 
> two bytes (RPM and MPH).
>
> The earlier post about poor resolution made a good point (25 RPM 
> and 1.0 MPH), you can however query the raw time between cam 
> sensor pulses and the raw VSS count and do your own math to get 
> as precise as you wish.

At least some of the P4 ECMs compute the vehicle speed as a 16 bit
number - one byte for MPH and one byte for the fractional portion.  If
you peek at both of these bytes, it will give you the vehicle speed in
increments of 0.004 MPH.  This 16 bit value is filtered though, so you
might want to grab the raw VSS count and timestamp data anyway.

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/