injector on time calculation

[NickG]

The ECU in my car uses injector on time per cylinder revolution (called Ti)
as one of the axis for the lookup tables. I'm trying to determine how this
calculation is done, and would like to run it through the list to get some
feedback on my results.

I'm certain that the following inputs are used in the calculation:

 air mass meter input (in kg/hr)
RPM
injector size

 From these 3 inputs, 2 can vary (air mass and RPM) and one is constant
(injector size). I'm also assuming the following conditions:

 A/F ratio = 14.7
# of cyl = 6
inj. size per cyl = 35.25 lb/hr

 I'm trying to solve for Ti (in ms/rev/cyl), so the basic formula I've come
up with is:

 Ti = [ (kg/hr) / (RPM X injsize X AFratio X numcyl) ] X k

 where k is a unit conversion factor converting kg/hr, RPM, and lb/hr to
ms/rev and equals 132,000.

 Thus,

 Ti = [ (kg/hr) / (RPM X 35.25 X 14.7 X 6) ] X 132,000

 Ti = [ (kg/hr) / RPM ] X 42.457

 Does this sound reasonable? Am I missing something?

 Nick


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