93 Z28 Disassembly - Found TPS voltage limits & default value

[Mike]

>I tackled the Throttle Load Axis Variable (it is used heavily to
>determine TCC lockup).   I still don't understand exactly what
>is is calculating, if someone wants to look at the flowchart,
>it is at http://www.hit.net/~rah/F43B_F4C6.gif .    The 
>part of the code that I don't understand the purpose of is the
>A = A - B part, I don't understand exactly why.  The rest of
>things are pretty clear.  I have the things that confuse me
>marked as such.
>

The first one is where the PCM determines the "low" TPS voltage. What it
does is, if the current TPS A/D counts are less than the stored minimum TPS
voltage ($016B), the logic will use a first-order lag filter routine (at
FB63) and a very, very slow filter constant (at 8681 which is 01h) to "add"
this new minimum TPS reading to the current minimum TPS reading. This way,
the PCM has a "baseline" voltage from which 0% TPS is "started".

The second one is where the PCM determines the difference between the
current TPS A/D counts and this "minimum TPS" voltage - the SBA. The result
is what is used to determine the percent above "closed" (i.e. the minimum
TPS voltage) the current TPS reading is.

As far as I can tell, the approximate (ignoring rounding) translation of the
code between F46F and F48A is:

    % = (CurrentAD - "ClosedAD") * 111 * 4 / 256

or

    % = (CurrentAD - "ClosedAD") / 1.73

where '%' ranges from 00h (0%) to FFh (100%).

If the "closed" TPS is, say, 30h counts (0.94V), the 100% TPS reading should
appear at about:

    255 = Delta / 1.73
    Delta ~= 147 counts

30h + 93h == C3h or about 3.82V 


Any and all corrections welcome.

Hope this helps.

--
Mike