Injector Duty Cycle.

[Greg Hermann]

>>I would say that 80 or 85% is a good maximum duty cycle--at ANY engine
>>speed, for the cooling reason, and also just to leave a bit of head room at
>>the top end.
>>
>>2 ms minimum on time and 2 ms minimum off time, again at any engine speed,
>>is a decent rule of thumb to avoid fuel delivery inconsistencies.
>
>I think that's an unreasonable assumption.  I've found that at idle using the
>stock Honda injectors (24lb/hr) that idle on a warm engine uses about 2ms pulse
>width for Stoich.    I found when I tried to use 4ms as my minimum time
>that the
>engine barely ran.  It may be that the injector at that pulse width is not
>opening completely but adding a too large value into the total injector time
>screws up all the other calculations.
>

I think you are reading what I tried to say backwards.

With a minimum on time shroter than 2ms, with saturated injectors, you may
not get consistent amounts of fuel delivered (and you will therefore get
rough, inconsistent running)  because the injectors will not operate
repeatably at a shorter pw. This time restriction shortens to maybe 1.5 ms
with peak and hold injectors.

A similar minimum off time restriction may well also apply. Of course going
from a 2ms to a 4ms pw at idle with an engine that idles well with a 2 ms
pw will make it not run--it would be twice as rich as it needs to be!

Greg