Just playing around with the cool spark bias (default 20 deg), now tunercat says that this is subtracted from the cool compensation sprak table. But after looking at the hack, the bias appears to be added to table.

I changed the cool bias from 20 deg to 3 deg, and went for a spin, the engine pulls way harder now. Could it be that I had way to much advance before? And could tunercat be wrong?

Tunercat now shows my cool spark adder table to all be increased by 17 deg now ( the change in the cool bias I made). If thats true then I would have like 45 wot advance. I think tunercat is wrong.

 

By changing the coolant SA bias to 3 degrees from 20 degrees, you have added 17 degrees of timing across the board. That is everywhere except during crank.

RBob.

 

Ok, but my hac shows that the bias is added ( + sign). So could it be that tunercat just doesn't show a - sign in front of the warm and cold bias's.


These bias's seem useless, I have zero'd them both out, and adjusted my tunercat tdf file to have no bias included in the main and cool spark tables.

 

The bias' are subtracted out after the stored SA is added back in to the double accumulator D (A,B). In the 7747 hack, the 'SUBB LD015' is subtract from accumulator B the contents of the location $D015 in the prom, which is the coolant SA bias.

 

I really don't see the point of these bias's. Anyone have any input on why gm used these, other than is easy to make a global change to the entire table. Anyway I find them confusing, at best.

As a side note, after porting my intake plenum out this winter, the amount of AE I need is huge (like 8X of what it was stock), also I've had to strech it out with the filters.

 

hmmm... Dont really know for sure. I heard it was to allow negative timing to be in the SA table w/o having to use signed bytes.

 

That makes sense...