Min. injector off time

[Scott Shotton]

bruce plecan wrote:
> 
> Please someone help me on this.
> "They" say not to run the injectors over 85% PWM,
> on time.  OK, from what I've read the lag time from
> V on till injector open can range from .0012 sec
> Peak+Hold to .0018 sec for Saturated.  Right?
> But when they say 85% if the injector was on for
> 85 days, and off for 15, then that would be a 85%
> on time, but the injector might be crispy by then.
> So what is a min. off time that would allow an
> injector to "relax"+"cool-off" enough??..
>   If there is this .0018 reaction time, would then
> a .002 sec. be considered a min. off time?????..
> If not what would be????.
>   Would be above be a new consideration for
> a high rpm motor for injector sizing????...
>   TIA  Bruce


This probably doesn't answer your question, but:  the injector probably
wouldn't have a problem if it were on 100% of the time.  If I am not
mistaken, and I could be wrong, the off time allows the driver to cool. 
I know an injector, or bank of injectors, with a low resistance flows
more current and can destroy a driver(s).  I have seen it many a time on
GM 2.8/3.1's.  The plennum design holds heat in and "bakes" the
injectors.  Injector resistance drops.  Drivers shut down.  I see about
8-10 of these engines a year with this problem.

If anyone knows different, please let me know.

Scott