[Diy_efi] Fixed frequency PWM batch mode FI

[Mike]

Theres been some discussion on this thread re selecting the
best injector timing/counter to handle a minimum pulse width at idle
and sufficient timing resolution to handle precision at high
rpm and higher load...

My crank angle sensor has 2 outputs (for straight 6), the first
is a pulse on each 120 deg  and the second a pulse each deg of
rotation. TDC (cyl 1) is handled by an extra wide 120 deg pulse
coinciding with 4 of the single deg pulses (or so it looks) such
that a simple AND gate can deliver a TDC pulse to the CPU.

>From what I see on a number of local vehicles in last 10 years
and this goes from the low cost bog standard sedans to more performance
factory cars they all seem to use very similar devices generating
two signals as described above.

To get around the problem touched on this thread re injectors,
surely one could use the one deg pulse in 'concert' with a best
fit (read higher res) 16 bit timer to provide the best of both worlds.
ie. The 1 deg pulse provides injector start, the number of pulses
from then on relative to rpm provide a coarse timing selected
by AFM and the fine timing provided by compensation factors
such as o2 and engine temperature, WOT transient etc...

This might mean a 24 bit entry for injector time, where 1st byte
refers to number of 1 deg crank pulses and the 16 bit value is
the raw 16 bit injector time period prior to compensation,



Regards

Mike Massen
Hm 08 9444 8961,  Fx 08 9384 0861,  Mb 0438 048961

Some power stuff here: http://www.iinet.net.au/~erazmus

Ancient Sufi saying:
        "Should your God save you from adversity, choose another God"


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