730 Spark Advance

[Bob Valentine]

I'm doing some last minute tuning on the spark tables, and need to get a
few things straight.   Base cal is AUJP.

1.  The actual measured timing at the crank is the amount in the table (32
degrees for example), subtracted from the inital advance (6 degrees in
AUJP).   Measured at the crank, this would be 26 degrees?    This is what
the scan tool reports as spark advance. 

2. Is the value for max advance at $026 is the max advance the ECM will
allow to be delivered, or the max value allowed in the table?  Given that
$026 is 39 degrees, the max advance possible measured at the crank would be
39 + 6 = 45 degrees?      If this is correct, a value of 42 degrees in the
table would result in 38 degrees crank advance, right?

3.  What are average highway cruise SA numbers?  I realize this varies
greatly, but what's a ballpark?  Stock AUJP table looks to only put in
about 31 deg. at highway cruise, less than I'd expect.

4.  Is there a good reason to use "Hiway SA mode" instead of just directly
tweaking the spark table?   

-> Bob Valentine
-> bob at tecmark.com

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