[Diy_efi] Newbie ? refined

[A6intruder]

Bob,

Your question #2 below suggests that you are mixing "sequential" with duty
cycle.  Sequential means each injector only fires when needed for it's
cylinder.  Duty cycle refers to the time open of one injector versus the max
time available for one cycle of that cylinder.  100% duty cycle is the only
time all injectors would be open at the same time.

I don't see any reason you would want to run 100% duty cycle. If you are
flowing enough air to max your duty cycle you no longer have control over
A/F as your airflow continues to rise.  Once you've hit 100% duty cycle you
can't get more fuel into the engine short of changing fuel pressure (but
then you're into a second control system and greater complexity with less
accuracy).  The factory wouldn't intentionally let 100% duty cycle happen.

If your intent is to add nitrous you will need some "head room" to allow
extra fuel to be added when you inject the nitrous.  I think at least one of
the "dry" kits injects the nitrous ahead of the MAF so that the computer
reads the nitrous as more air and automatically adds fuel.  With the EEC
Tuner you could go this route and then make adjustments to your MAF curve to
actually get that mixture right.  I don't know how much different the A/F
ratio is for Nitrous-fuel versus air-fuel.  After tuning this route for
nitrous it may be a problem if you go WOT without nitrous.

Hope that helps.

Daniel R. Nicoson
Equipment Exchange Company
Phone:  (814) 774-0888
Fax:      (814) 774-0880

-----Original Message-----
From: diy_efi-admin at diy-efi.org [mailto:diy_efi-admin at diy-efi.org]On Behalf
Of bob limo
Sent: Friday, December 13, 2002 9:18 AM
To: diy_efi at diy-efi.org
Subject: [Diy_efi] Newbie ? refined

I originally posted: ">Do you guys know if the wide
open throttle on most
>production sports cars is at the maximum duty cycle
of
>the injectors, or do most manufacturers have some
head
>room in the injectors like 20% more room?"

The reason for the ? was that I was thinking about a
way to just turn on the injectors 100% at wide open
throttle and run a little nitrous oxide as close to
stoichimetric as possible.  Problems are: 1) some on
this list say duty cycles are at max in general and
some say they are not. If there is headroom then in
theory you haev more fuel capacity to prevent a lean
burn. 2) events are happening so fast that are all the
injectors really spraying all the time at WOT anyway?
Things aren't really that sequential so I don't think
it matters if I dump fuel for those short times 100%
thru all injectors? 3)Does wiring up injectors that
way cause any bad feedback to ECU?  It is a real
hassle to figure out how to nitrous a dry manifold,
with minimal effort,  never ment to flow a wet
mixture.  I may end up fining that the headroom left
in stock injectors is so little that Nitrous just does
not work well this way.

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