spark advance curve modification

[Dig]

> I have a turbo car (8.7:1 compression, 91 octane required) with a GMP4 
> ECM. I KNOW where the spark curves are on the eeprom, my question is:
> 
> can someone give a description of a baseline tequnique i can use to 
> modify the spark table for "mild/medium" performance increase?

What kind of a powerplant is it? (4-cyl, v6, ?) I do some chip twiddling
on a 4.3 turbo V6... (GMP-4)

> example: increase advance for the lower load lines 1-2 defress, and the 
> upper load lines 3-4 deg,  or increase beginning of all lines 1 degree, 
> middle of lines 2-3 degrees and ends of lines 1-2 degrees..

Let me preface this by saying that the following assumes you have an
increased fuel capacity or better octane or better intercooling (or
all the above)...

Your timing table is set up as an absolute MAP vs. RPM vs. timing, no?
With a turbo, you'll want to add more timing at low MAP (~100 KPA abs.)
and low RPM (600-2000) to get the turbo to spool up a little quicker. 
Avoid big jumps at high load (170-180 KPA abs.), you'll end up getting 
a lot of detonation.

A lot of this tuning is best done by adding timing slowly, and watching
to see what effect this will have on knock retard. Keep in mind that shifts
in ambient temp will effect this dramatically, you'll see much more knock
on a hot day.

I'd try to bump up the ESC attack rate for the testing period, so that if
knock does occur, timing will be taken out quickly. Might also want to 
bump up the max retard parameter to allow more timing to be taken out.

Personally, I'm of the mind that performance increases should be acheived
via increased boost and *decreased* timing. It's tough to determine where
the decreased timing will hurt you more than the increased boost gains you,
however.

 
> engine is MAP controlled, not MAF and HAS ELECTRONIC SPARK CONTROL with 
> knock sensor.. can i rely in knock sensor to protect against possible 
> over-advance on eeprom if i accidently use a "FA" insted of "2A" ?

As long as you keep a close eye on knock retard during your test runs,
you should be ok. You'll hit the max retard limit set in your ECM, which
should tell you that you've got a little too much timing somewhere.

Do you have a 2-bar MAP, or a 3-bar? What's the service # on your ECM?

Dig
dig at syclone.cc.und.nodak.edu