first one!

[Roger Heflin]

On Thu, 4 Feb 1999 jgwynne at mrcday.com wrote:

> 
> Bruce mentioned the 730... I would like something pre-LT1, V8, and
> manual transmission. I'm currently using a 165, but would be willing
> to do a 730 swap if we make progress. I have two goals: (a) to be
> able to tune my current engine and (b) to "flowchart" how one of these
> work.
> 

I think on the tuning side all of them are probably the same.  Ie.
there is a ve table, a wot table, and probably an injector scaler,
where the tables are differs, and exactly how they are indexed
differs.   

I noticed on mine the ecm has about 5-6 different rpm values.  It has
a N*12.5, a N*25, a N*31.25 and a couple of other ones with odd
scaling and offsets.   I am still working on where each is used, but
it appears that the N*12.5 is used below 750 (idle) and the N*31.25 is
used above 4000 rpm.  I don't now if the other ecms are the same, but
my guess would be that they are.   Because of the change over between
rpm data, below 4000 the WOT table goes by 400, above 4000 it goes by
500 rpm per step.   I am also guessing that to stablize a higher rpm
idle (>750) you would really need to raise the area that the
12.5rpm/count is being used in, to above the "new" rpm speed.  I am
going to attempt this to see if it improves my cars idle.   All of the
extra idle numbers are within 2-3 bytes of the idle number that is put
out to the ALDL port.  I have also considered changing the ALDL
output rpm to use the 31.25 value, but right now I don't get above
6375 that much.  If you were reving the engine high, you would
probably want to change that value.


				Roger