why is above a tuneable parameter?

i did some reading up and i understand there is a time element restriction to fuel at higher rpms with TBI(2). the injector has to be open sufficient time to fuel the required A/F and then close for next opportunity. i see a chart that refers to "PWM time" which appears same as above terminology. thay suggest for low impedence injs that time to open is 1.0 msec. they dont state it a variable but a defined time.

i assume our inj's are low impedance?

the time to open is variable ? i can see voltage changes as one variable but assuming voltage adequate(11.9+) why a tunable parameter? seems the off time before next on would be the determined by command from ECU to achive the A/F? i am about to change the bias for more fuel PE.

 

The opening time characteristics vary by injector. Depending on pintle weight the injector might have a design on the low end of allowable resistance. When they start fudging coil designs to get better opening characteristics, you can count on the opening times being a variable.

If you change injectors and, and injecotr BPW (ie doing the proper math), then a VE table should be correct with no changes. If not then the opening time variable is *off*.

 

Ron,

When you get the chance to look at the EBL code, you'll see that the IB(Injector Correction Offset) is variable on the basis of voltage. I think your question has to do with "why is IB adjustable in the $42def". As Bruce has said, it allows for the use of various injectors. All the stock bins I have seen use an IB of 396msec. RBob however tells me that he has measured the opening time for BBC injectors like ours and its in the 700+msec range.