[Diy_efi] Timing Calculations

[Mark Higgins]

Hey, guys.  I'm new to the list, so I have no idea if this has been 
discussed before.

I'm making my own EFI here.  It's a basic unit that will do 4 cylinder 
sequential injection with direct fire.  Currently I'm working on 
calculating the event timings (ignition and injector on/off) based on 
the trigger inputs.  I'm basing the engine speed calculation off of the 
time between sync/home trigger points.

Since my timing is all based on the previous engine cycle my question 
is, is it worth it to try to anticipate acceleration/deceleration into 
my timing, or is it negligable and not worth it?  Since the timing is 
based on the last engine cycle, if the engine is decelerating very 
quickly, I'm not certain how off the timing can get.  I should really 
try and calculate the effect, but I'm hoping someone has already thought 
through this already.

I was thinking of checking the trend of the last x number of cycles and 
trying to anticipate whether the engine is accelerating or 
decelerating.  It would never be perfect, but it would average the 
timing out better.  Or maybe using the throttle sensor to anticipate 
accelerationg/deceleration, kind of like a throttle pump, but for timing.

I think this anticipation scheme is probably overkill, but this ECU will 
be controlling a road race engine and I was just trying to think of ways 
of improving the timing and maybe transitional response.

Mark Higgins
DirtyLude