TPS voltage and ECM interpretation

[Ludis Langens]

> "James S. Fearn, Jr." wrote:
> 
> The ECM
> then interprets that scale as 0 to 256 bits accordingly, right?

Actually, 0 to 255.

> That leaves me
> asking what does the ECM consider as 0% throttle and 100% throttle?

0% is the lowest TPS reading the ECM has seen in a while.  If the TPS
goes lower than the "lowest seen" value, then the new value becomes the
"lowest seen" number.  Some ECMs have code that tries to pull this value
back up if it never gets that low, but this can't work very well.  This
is why the ECM should be reset whenever the TPS is changed/adjusted.

100% is anything over "lowest seen" plus x where x is a value specified
in the PROM.  It is usually set so that 100% is achieved at quite a bit
less than 5 volts on the TPS.

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