Injector control

[Espen Hilde]

Hi!
I have the same experiance with Electromotive tec1 unit.I have a idle
injector ms. at 1.35.with 350ccm`s
peak and hold.I can try to finetune my idle putting in small incrediments
in numbers and down load to the 
ecm, but nothing happens ,at a certain point the calibration  jumps,maybe
to 1.45.This results in that I can choose from having 1%co or 3%co.The last
digit on the volumetric tables do`s not work.
The way to get it right is maybe to use fuel pressure , to adjust........if
the ecu tryes to compensate for
temp or sumpin , is the finest compensation to go to 3%co............?
Espen Hilde
 Greg Hermann wrote:
> > 
> > Hi guys--
> > 
> > A new thread. Bought a copy of the latest issue of "SUPER CHEVY" cuzza
it
> > had a four page  article  on the Fel Pro SEFI 8 LO ECU in it. I
know-and I
> > NEVER look at the pictures in "Sleazy Rider" either--!! [DUCKING!! :-)
]
> > 
> > Anywayz--in the article, they mentioned that the FP unit has an
injector
> > pulse width RESOLUTION of 8 MICRO seconds--and bragged on this being
far
> > better than a resolution of 64 mi. s. I kinda assume this to mean that
the
> > smallest change in (adjustment to) injector pulse width which their ecu
is
> > capable of making has a magnitude of 8 mi. s. and that (most likely
their
> > competitors, brand A and brand H) other units can only make adjustments
to
> > pulsewidths 64 mi.s at a time, no smaller.
> > 
> > This raised several questions in my little brain.
> > 
> > First--has anybody figured out how small an incremental adjustment to
> > injector pulse width time the OEM ecm's are capable of making (GM,
Bosch,
> > etc.???)?? If so, is it posted anywhere??
> > 
> > Second, a few months ago, I talked with Lance Ward, the FP tech guy, on
the
> > phone. He said (among other things) that they program their ecu so as
not
> > to allow injector pulse widths shorter than 1 MILLI second. I assume
that
> > this number presumes the use of p&h injectors, and that they have
verified
> > that the p&h injectors work repeatably down to 1 ms. pulse width. But
the
> > light bulb that came on is over the fact that an 8 mi sec adjustment to
a
> > pulse width of 1 ms. would make a 0.8% change in amount of fuel
> > delivered--a reasonably fine adjustment increment when in a search for
a
> > good idle. Whereas a 64 mi sec adjustment to a 1 ms pulse width would
only
> > give a 6.4% change in amount of fuel delivered--way to coarse a
> > change--like, for example, you would have a choice of running 12.4:1;
> > 13.5:1; or  14.3:1 mixture ratio at idle, and nothing in between- a
> > situation which would leave you without a prayer of getting a decent
idle
> > if your injector pulse width needed to be as short as 1 ms at idle.
And,
> > even if your idle (only) needed a 2ms pulse width, a 3.2% increment of
fuel
> > adjustment is still too coarse an increment to do a REALLY good job of
> > adjusting things at idle.
> > 
> > I guess the apparent moral of this story, at least to me, is to temper
any
> > info anybody gives you about how short a pulse width given injectors
will
> > work with by asking how fine an adjustment to pulse width the ecu which
> > they are peddling will make!! And if you are putting together a setup
which
> > is gonna use big injectors, and need a short pulse width to idle, you
> > really need to make sure that you are gonna use an ecu which will make
> > small enough incremental adjustments to injector pulse width too!
> > 
> > BTW--how small an incremental change in injector pulse width can the
332
> > project hardware make, and what level of attention is being paid to
this
> > issue in the 332 project software??
> > 
> > There is a lot of room for comments here, so let's have at it!!
> > 
> > Regards, Greg