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Thread: wideband logging

  1. #31
    RIP EagleMark's Avatar
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    Quote Originally Posted by RobertISaar View Post
    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.

    Code:
     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

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  2. #32
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    Quote Originally Posted by steveo View Post
    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.

    Quote Originally Posted by steveo View Post
    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?
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  3. #33
    LT1 specialist steveo's Avatar
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    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.

  4. #34
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    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?

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  5. #35
    LT1 specialist steveo's Avatar
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    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.

  6. #36
    LT1 specialist steveo's Avatar
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    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!

  7. #37
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    i took a quick look and it appears that the code used for the open loop AFR table is out of the ordinary.....

    however, it looks like the open loop target AFR is stored to byte 195 as X * .1 = AFR.

    pretty quickly after it is stored to, it(or a couple of alternate bytes) is compared against a hardcoded value of $93, which in decimal is 147. i don't think this is a coincidence, but i haven't dug in far enough to be certain.

    almost immediately after, the MAF calc is done.... odd order to do things in.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  8. #38
    LT1 specialist steveo's Avatar
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    i follow you so far, and i get the open loop lookup

    i figured there'd be a more obvious branch between open and closed loop behavior after the maf or speed density calcs are done, but i wasn't thinking the obvious, since i've observed it uses the BLM cells to scale open loop calcs, there's very little difference between closed and open loop procedures.

    the programmer in me thinks there must either:

    - a branch where it either chooses to do an open loop table lookup, or store a constant instead (starting to doubt this)
    - something that does the open loop lookup regardless, then writes over that byte with stoich when it checks the closed loop bit
    - stores stoich, then branches somewhere and replaces it with the open loop lookup if the CL bit is unset.

    i have yet to see any of those things, though

    regardless of this thing, i want to look into PE too to try to understand OL vs. CL a bit better, since in PE it stops using the open loop table and does it's calcs on stoich + blm + pe tables, but this happens even with the CL bit unset.

    might give me more clues or just more fun reading.

  9. #39
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    scenario 2 is what i would expect to find.
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  10. #40
    LT1 specialist steveo's Avatar
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    code in question:

    Code:
    6166	13 2D 04 04     @170	brclr	l_002d_fts_0_stat_byte, #%00000100, @171  ;  1 = ENGINE CLOSED LOOP
    616A	13 34 20 0A     	brclr	l_0034_tts_1, #%00100000, @172
    616E	B1 01 95        @171	cmpA	L0195
    6171	25 0B           	bcs	@173
    6173	B6 01 95        	ldaA	L0195
    6176	20 06           	jr	@173
    ;
    6178	81 93           @172	cmpA	#$93
    617A	25 02           	bcs	@173
    617C	86 93           	ldaA	#$93
    617E	12 25 01 04     @173	brset	L0025, #%00000001, @174
    6182	13 24 80 03     	brclr	L0024, #%10000000, @175
    6186	BD 32 A0        @174	call	L32A0
    6189	13 30 10 03     @175	brclr	l_0030_fts_3_stat_byte, #%00010000, @176
    618D	B6 01 D2        	ldaA	l_01d2_fts_7
    6190	B7 01 96        @176	staA	l_0196_tts_9
    6193	B6 20 28        	ldaA	b_2028_sw_b3vats_b2spddens_b0tcs
    6196	85 02           	bitA	#%00000010                        ; what switch bit
    6198	27 03           	beq	@177
    619A	7E 63 79        	jmp	@199

  11. #41
    LT1 specialist steveo's Avatar
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    i do like how it looks, basically if engine closed loop status byte unset, it doesn't get to @172, and if it does, it does stick 0x93 in that register, but i cant' follow what happens to it after for some reason?

  12. #42
    LT1 specialist steveo's Avatar
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    consdering how quickly i hit a brick wall with this assembly every time i try to examine a routine, i'm going to put my direct research into EE on hold for a bit, and play with this toy:

    http://www.hc11.demon.nl/thrsim11/info.htm

    since i've never developed anything reasonble for 68k, i feel like im learning backwards. going to write myself a fake ecm in this sim, then go back.

    once im done, might be entertaining but probably unsuccessful to try to sim EE on this program, epsecially if i could get two instances going to sim t-side and e-side with comms...

  13. #43
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    i predict that will work well with the code on a P6 unit..... but likely to be completely useless on a P4, due to how different they are from a normal 6811.

    the hardware...... i don't know about that. there are a lot of chips on-board that have no formal documentation and are VERY application-specific. the way the injectors are handled are the first thing that comes to mind.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


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  15. #45
    LT1 specialist steveo's Avatar
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    ok, so.. im thinking that's probably it, after poking around some more.

    it's added/subtracted to a value stored at L0197 via a short subroutine, depending on a status byte. it stores the result in L0196 a bit later on.

    L0197 seems to be calculated earlier on from a large subroutine concerning fueling calculations that i don't quite understand right now; but i betcha it's blm/int/corrcl control input?

    why add/subtract, though? i don't get that. perhaps this is a matter of the base afr being stored in L0196, and scaled up/down a fixed amount according to BLM?

    i assume L0196 is a prime fueling calc, seems a bunch of AFR values end up getting dumped there, and also notice that's the byte that's compared to 0xFF to branch for fuel cut

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