table at 0x26F2 appears to be, unless im misunderstanding it, 5x15 of map vs coolant, which means the fueling routine is probably fairly temperature oriented, and operates only at either really coarse or a specific range of MAP values.

this may point towards this actually being the wall pooling compensations

result stored in 0x00FD, used only once. it appears to make a choice based on rpm,

Code:
6699	CE 00 8A        @262	ldX	#$008A
669C	DC 7A           	ldD	L007A
669E	A3 00           	subD	0, X
66A0	DE A1           	ldX	l_00a1_ref_period_12x
66A2	BC 26 ED        	cmpX	L26ED
66A5	25 0D           	bcs	@263
whether to perform this calc on the result:

Code:
66A7	DF FB           	stX	L00FB
66A9	96 FD           	ldaA	L00FD   ; load mystery value
66AB	C6 52           	ldaB	#$52   ; multiply with dec 82
66AD	3D              	mul	          ; ..
66AE	89 00           	adcA	#$00   ; add carry bit of nil back to register?  i don't understand that
66B0	16              	tAB	  ; result to register b
66B1	4F              	clrA	
66B2	20 0D           	jr	@264
.. or this one

Code:
66B4	DD FB           @263	stD	L00FB
66B6	8F              	xgDX	
66B7	96 FD           	ldaA	L00FD  ; load mystery value
66B9	C6 F6           	ldaB	#$F6  ; multiply with 246 ??
66BB	3D              	mul	   ;
66BC	04              	lsrD	   ; ok im lost
66BD	04              	lsrD	   ; 5 right shifts
66BE	04              	lsrD	   ; need more coffee
66BF	04              	lsrD	   ; 
66C0	04              	lsrD	   ;