7747 spark control questions.

[Programmer]

>In trying to understand this a little more I have a few questions and
>suppositions. Need you guys to yea, nea or just plain shoot hole thru them
>for me..
>Thanks.
>
>Initial spark advance: Lets the ECM know what the dist is set at
physically,
>but all the bins I've checked seem to be set at 0.. does this mean those
>application(all trucks) dist are set at 0 physical from the factory or have
>I got what this does wrong?

Dissies are set "0" with the EST disconnected. The bins should show main
spark bias at 10 degrees.

>
>Warm Bias (main bias in TC): Just so neg advance can be applied in spark
>table as pos numbers!? Why is this necessary? If the dist is set at 0
>physical why would neg numbers be needed in main table?

Warm bias is 10 degrees. Negative numbers work out when you run
the formula in the tuning docs...I really don't know why the neg numbers in
the tables--If you look at the areas that have the neg numbers, I don't
think
you'd be in those areas for any more than a few milliseconds...90 kpa @
400-600 RPM ?

>Cold Bias: So neg numbers can be applied as pos numbers in coolant(engine
>temp) compensation table. I can see this, but is this table(would think so)
>always active?  Then it would seem both Cold and Warm bias' are active all
>the time!?
The table is always active--cold bias is inactive at "x" temp (20 degrees
advance).

>PE spark: Trying to compare this to a function in a mech dist(I know the
>elect always for more specific spark control) the only reason I can see for
>this is either to use lower numbers in main table for emissions reasons and
>add it back when needed for acceleration or like the PE enrichment to get
>some spark going faster than would happen waiting for a value lookup???

This seems like a "more fuel" spark adder table. The values range from a few
to 5 degrees more advance. Call me crazy, but I set these to "0" and just
tune
the 90 through 100 kpa table differently. May not be the right way, but it
works
for me...

Lyndon.


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