101 clarification

[Bruce Plecan]

>Bruce Plecan wrote:
>
>> There is a spark adder, called main spark bias, which moves the
>> entire table up or down in value.   So lets say your at 0 degrees
>> advance with a spark bias of 10 degrees.   If you drop the spark
>> bias to 0 then your initial timing of 0 becomes -10.   There are some
>> engines that are fussy about the initial timing, and spark bias.
>> Generally I find alot of engines like 6d initial, a spark bias of 6.
>> Now just to really foul things up/and/or confuse them there is a cold
>> spark bias.  Normally I have a fair amount there (15ish).  Then with
>> the above 16-20d BTDC idle timing.
>>     Whiether this actually pushes the timing to AFTC I don't know,
>> till after I get the bench stuff running.  From test driving it seems to,
>> but I have trouble setting timing by seat of the pants.
>
>So Bruce, do you know where this main and cold spark adder is in the
>PROM map?

Yes, but gotta do some more testing with it.  It's included in the math at
the tables, thou, so it's not a giant thing in my book.  There is
enought major stuff to keep straight, for the moment.
>
>Also, just out of curiosity, the VE table from your tuning notes peaks
>in the 60% range.  That seems low...  Is that table really a measure of
>VE, or is it just values that work?

Goes back to what I said early on that all these numbers exist for
computer reasons.  You can lie to the computer, and all it does is
generate values on the code used.  Remember that in the 747 it
uses a PE, so with those numbers the totals got to about 100.
Also in some of the other type ecms the numbers never exceed
80, and that is so there is available volume of fuel to allow for
accelerator enrichment.  I think using the term VE for the fuel is
about the most misleading term possible, but folks are paid
lots more than me to figure this stuff out.
>
>--steve
>
Cheers
Bruce
>--
>Steve Ravet
>International Meta Systems
>http://www.imes.com
>steve at imes.com
>