Synch vs Asynch fueling

[EagleMark]

That's funny! Your Asnc is set off yet it comes on, my Asnc is set on and it won't come on!

I'll look at your log later and add an Injector Duty Cycle % value. With that and BPW times you should try the stock BPC and calculated BPC to new fuel pressure and see what happens.

FYI the pictures above are a stock engine and stock pressure yest shows 110% duty cycle. All these TBI systems are marginal (short) of fuel to begin with.

Anyone reading this! Every Injector Duty Cycle % value I have found in all ADX files is WRONG! It's only half! $42, $0D etc... 49% = 98%... Static!

[chevmasta]

With that and BPW times you should try the stock BPC and calculated BPC to new fuel pressure and see what happens.

FYI the pictures above are a stock engine and stock pressure yest shows 110% duty cycle. All these TBI systems are marginal (short) of fuel to begin with.

Anyone reading this! Every Injector Duty Cycle % value I have found in all ADX files is WRONG! It's only half! $42, $0D etc... 49% = 98%... Static!

I already tried the calculation with the fuel pressure........we came up with about 120.

I was lean at idle........and lean up top.
150-155BLM values with nothing else touched other than lowering the BPC from 142-120.

[RobertISaar]

the IDC calc being correct depends on if whoever wrote the ADX accounted for the injector firing pattern. my cars are all double-fire MPFI and SFI and their ADXs are setup as such.

[EagleMark]

chevmasta had quoted he found it on FullSizeChevy and I had found it as well, from 2007 IIRC. It was wrong then and it's wrong now for TBI...

[EagleMark]

Back to Async... From what this disassembly says it was never based on time without DRP... the 12.5 is the MAX Async BPW. 80 was divided by firings all based of DRP converted to Duty Cycle.

 ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
; Here to enter asnyc fire, convert sync BPW to async firing time
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
;											
L8507	CLRA				;
	CLRB				;Clear out sync BPW
	STD     L3FCE			;TBI injector driver hardware
	JSR     LF08A			;Short delay
;
;-Convert BPW to a duty cycle
;
	LDD     L3FC0			;DRP
	ASLD				;x2 for quad injector firings
	BCC     L8518			;Bra if no overflow
;											
	LDD     #$FFFF			;Clear overflow
;
L8518	XGDX				;Swap result into X    
	LDD     L0271			;Sync BPW
	FDIV				;BPW/DRP x 65536, now %DC 
;
;-%DC x (1/80 firings), or 12.5 msec per asnyc firing