Duty cycle formula

[Carl Summers]

Hi,
   So in general it's an OK equation but not an absolute???  Does GM use
asynch and synch on port injection as well as TBI? If you are measuring
commanded PW at the injector does the formula work again??? Wait...DUH....
Do all ECU's switch to sssf at some rpm point to reduce stress on the
drivers??? My head hurts...wonder if this would be a good topic at the
tavern :)

Bruce,
   That's pretty much how I came up with the formula.
-Carl Summers
p.s. ever notice when your sick and still have work to do you somehow become
a pharmacist.....Nyquil, Alka seltzer plus, and vivarin.....bzzzzzzzzzzz :)
  (_\_)   (_/_)  shake shake shake.....I am Cornholio....Fire, Fire  ack!

-----Original Message-----
From: owner-gmecm at diy-efi.org [mailto:owner-gmecm at diy-efi.org]On Behalf
Of Walter Sherwin
Sent: Friday, August 25, 2000 4:50 PM
To: gmecm at diy-efi.org
Subject: Re: Duty cycle formula


Your first equation, YES, but only for SSDF operation (fire a bank once per
crank rev).  When SSSF kicks in (fire a bank once per two crank revs), then
NO.

A transition to ASYNCH fuel, from SYNCH, would further mess with this
equation.

Your second equation, YES, but only provided that the injection event is
"allowed" to span the time frame of two crank revs in the logic.  Commonly,
it is not allowed to, and in fact is oft constrained to a variable window of
opportunity based upon operating mode.


Walt.



> Hi all,
>      I am wanting to verify a formula with you guys that I have been using
> for quite some time...I have a terrible cold and must be using a different
> part of my brain today :) Does this seem like a correct formula???
>
> PW x (RPM/60) / 1000 = duty cycle for bank fire
>
> PW x (RPM/120) / 1000 = duty cycle for sequential
>
> Am I sick or is stupid is as stupid does??? :)
> -Carl Summers
>

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