is the bpw hard coded in the pcm at wot ?,or does the pcm adjust them according to the long term /short term fuel memory(blm/int)?or is it up to the programmer of the pcm? tring to figure out if I need bigger injectors ,I am seeing 18 and 19 ms of pw @6000 -6200 rpm

 

Pulse width is a calculated value. Doesn't matter whether its in closed loop or PE mode. PCM looks at the mass air flow, divides it by the target A/F ratio, multiplies by the long terms/128 (whether is uses the long terms in PE mode depends on whether they would add or subtract fuel) and ends up with the required fuel mass flow rate. Then it figures the pulse width (based on injector flow constant and offsets) required to deliver this much fuel in two revs of the crank.

A 19mS pulse width at 6,200RPM is a 98.2% duty cycle. That's too high. The only question I have is whether the "BPW" is the actual pulse width, since I've seen engines not running lean when DataMaster indicates duty cycles above 100%. Possibly the BPW does not include certain correction factors. In any case, your injectors could stand to be larger.

 

Mine reads 18mS at 5050 RPM WOT. This is OK? Spark advance is 36 degrees. o2s in the 930-950 range.

 

I do not have datamaster,yet but I got the #'s from freescan , is this a reliable source? thanks you seem to know it all

 

anyone use freescan? is it known to be correct?

 

At 5,050RPM there is 23.76mSec available for the injectors to fire. 18.0 / 23.76 = 75.8% duty cycle..... that's OK.

I don't know how Freescan compares to DataMaster with regard to duty cycle.