How to get injector "on time"?

[rhuish at goldrush.com]

Brian,

I'm setting up my table in 500 rpm steps. Since the use is for 300+ci engines I 
felt the steps could be somewhat "coarse". 

I'm writing the program in Pascal, which I am most familar with, to test the logic 
flow. Planning to compile the code to determine the amount of code space 
needed, then use one of the 68hcxx series. 11,12 or 16??

Here is the these equations for injector pulse width:
	if (RPM <= Cranking_Speed)
	  Air_Fuel_Ratio = Cranking_AF_Ratio
	else if (RPM <= Idle_Speed)
	  Air_Fuel_Ratio = Idle_AF_Ratio
	else
	  Air_Fuel_Ratio = Running_AF_Ratio

	Pulse_Width = Air_Fuel_Ratio * MAP * Efficiency[RPM] * Cold_Engine 
	+ Open_Time

Where:
Cranking_Speed	RPM value below which the engine is "Cranking"
Idle_Speed		RPM value below which the engine is "Idling"
Cranking_AF_Ratio	constant Air/Fuel ratio while cranking 
Idle_AF_Ratio		constant Air/Fuel ratio at idle 
Running_AF_Ratio	constant Air/Fuel ratio running 
Efficiency		Table of efficiency factors based on RPM
Open_Time		time it takes for injector to open
Cold_Engine		constant to increase A/F ratio when cold

Brian Lewis wrote:
> Hi all,
> 
> I am designing a simple FI controller out of an 68hc12 using C. I plan on
> measuring MAP and RPM and using these parameters to lookup a value for how
> long the injectors should be open in a 2-D table. My question is how fine
> must the resolution in the table be for smooth transitions between
> operating conditions and will I have to interpolate between points. Thanks
> in advance.

Bob Cuda-65 - Angels Camp, Calif.
cudabob at workmail.com
http://www.goldrush.com/~rhuish/