Originally Posted by
WS6FirebirdTA00
I think you lost me even more lol
Where did the 300.5 come from? Is this 300.5 crank degrees after starting the power stroke?
((boundary value +normal value)90)-784 = where in the cam timing the injector is finished firing. if you took the normal value and multiplied it by 90, it would give you exactly where (based on crank rotation) in the total engine cycle it finished. where does a normal 4 cycle engine start? thats the reference point
What is getting me here is that if the injection end is after the inlet valve is already open, changing the values small amounts won't matter as that is the end of the injection. At short pulses for idle it would still keep it injecting when the valve intake valve is open and exhaust is closed.
if you use engineers xls sheet, you will see that you can easily work it to end wherever. chris, i think it was, stated that the end point is simply the point from which the hardware calculates the injector firing point. you say you want it to end there, then the computer determines where it starts. why gm did it this way i dont know. the consesus on the stock settings however is fuel mixture, emissions, and other variables that are based on the cam design.
If the injection ends before the intake valve opens, the small changes that are being made still inject all the fuel before the valve is open. So it would take a big change to get rid of raw fuel going out the exhaust at low engine speeds.
a small change, by a tenth lets say, is still around a few degrees worth of crank rotation
Forgive my ignorance, I thought I had this but read some conflicting posts and it threw me all off.
I want to say all injection is finished at 59.5* BTDC while on the exhaust stroke, which is before the intake valve even starts to open. That would mean that changing the values by .2 or .3 would only delay injection slightly and at low engine speeds should not show a difference, yet people say it is. That makes me think I am totally wrong.