wideband logging

[RobertISaar]

follow the BPW calc far enough back and it will most certainly be involved..... may be faster to find working forward though, since the airflow calculations are pretty well understood. once airflow is calculated, the ratio of fuel to mix with the air shouldn't be too far after.

[steveo]

makes sense, i'll try!

i'd expect a fairly obvious branch somewhere, where it either does a lookup on the open loop fueling table, or based on (this variable), then scales it with all the closed loop stuff, right? i assume it'd check the closed loop enable bit itself as its sole condition

i think i can chase it based on those assumptions.

[steveo]

also the assumption that 0.10X+0 on one byte seems to be the conversion for most other cals when AFR is specified, including the open loop target table in EE, so it's more than likely i'd be looking for 0x93, right?

[EagleMark]

follow the BPW calc far enough back and it will most certainly be involved.....

Yup... From other masks it is the first thing used in BPW calculation. I believe both injector flow and displacement has been found in $EE, so reversing should find one more number in the calculation.

The value 1461.5 below is the Stoich AFR, where PFI uses 365.375 which is 1/4 of the TBI setting, I'd guess this is to do with firing of injectors per cycle difference.

 TBI 
					;   Val = 1461.5  * (VOL/RATE)
					;           VOL  = Vol of 1 Cylinder in liters, (0.7125l)
					;           RATE = Injector flow in gms/sec
					; 				   5.7l = 7.71 gms/sec (61.2#/HR)
					;				   (VOL/RATE) = 0.0924	l/gm/sec
PFI 
					;    Val = 365.375 * (VOL/RATE)
					;           VOL  = Vol of 1 Cylinder in liters, (0.7125l)
					;           RATE = Injector flow in gms/sec
					; 				   5.7l = 1.92751 gms/sec (#/HR)
					;				   (VOL/RATE) = 0.3696 l/gm/sec

[RobertISaar]

makes sense, i'll try!

i'd expect a fairly obvious branch somewhere, where it either does a lookup on the open loop fueling table, or based on (this variable), then scales it with all the closed loop stuff, right? i assume it'd check the closed loop enable bit itself as its sole condition

i think i can chase it based on those assumptions.

could be done a few different ways, but that is a good way to start searching for.

also the assumption that 0.10X+0 on one byte seems to be the conversion for most other cals when AFR is specified, including the open loop target table in EE, so it's more than likely i'd be looking for 0x93, right?

MIGHT.... but IIRC, 8D and probably DA did it in 16-bit?

[steveo]

good point! all other afr specs in ee being 8 bit 0.1N, never would have thought

I didnt have a ton of time today, im at work, but i tried to cheat and dredged through the areas in e-side where all the other tables/constants relating to afr are stored; didnt find any unknown 8 bit values of signifigance that were referenced by the calculations in question.

[EagleMark]

There's so many notes in the partial $EE disassembly that refer back to being same as AHNT that maybe looking at that would give a clue?

[steveo]

i think i've just brickwalled for today; never read the ee fueling calcs in such detail and it's a lot to try and understand for a noob.

also i got a bit sidetracked reading the t-side code for unrelated matters, finally got around to figuring out why the auto/manual flag in my xdf never worked. it was a drunken typo i think.

[steveo]

I've followed beginning to end of both maf and sd open loop closed loop fueling calcs, and understood the majority of what's going on, but it still isn't jumping out at me, that's for sure.

its a fun read anyway!