Injector control

[EFISYSTEMS at aol.com]

In a message dated 11/26/98 8:47:26 AM Pacific Standard Time, bearbvd at sni.net
writes:

<< Subj:	 Re: Injector control
 Date:	11/26/98 8:47:26 AM Pacific Standard Time
 From:	bearbvd at sni.net (Greg Hermann)
 Sender:	owner-diy_efi at efi332.eng.ohio-state.edu
 Reply-to:	diy_efi at efi332.eng.ohio-state.edu
 To:	diy_efi at efi332.eng.ohio-state.edu
 
 >-----Original Message-----
 >From: Greg Hermann <bearbvd at sni.net>
 >To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
 >Date: Thursday, November 26, 1998 10:02 AM
 >Subject: Re: Injector control
 >
 >
 >>>Hi Greg,
 >>>A couple of thoughts regarding PW.
 >>>1). The smaller you make the PW (resolution) the more Processing Power
 >>>(MIPS) you need in an ECC or it forces the manufacturer to adds an
 >>>automatic sequencer so as to keep the costs under control.
 >>>2). Those of us who do performance modifications would like to add
 >>>larger injectors.  With the low cost ECC's you wrestle with a large
 >>>minimum PW which complicates idle and emmisions.
 >>>Ron
 >>I thought that was what I was trying to say!! Sure, you need more
 >>processing power and a faster processor to get smaller pw resolution. With
 >>a bigger injector, you need a shorter pw (higher turndown ratio) to get an
 >>idle that works. so you go to p&h injectors, but if you do not have fine
 >>enough pw resolution,  you still do not get decent idle tuning. Like
 >>anything else, you get to spend more money to do it right!!
 >>>> Regards, Greg
 >
 >Wouldn't just using a lower fuel pressure work?.  So as to at least have the
 >injector fully on?.  Do a rising rate device, rather than a
 >1:1..   That one Bosch PWM FPR is beginning to sound better
 >all the time.
 
 >Bruce
 
 Sure--adjusting fuel pressure will get you where you need to go to adjust
 idle properly if you are stuck with big % steps in fuel delivery and pw at
 idle. And this is a perfectly appropriate way to make do if tuning with a
 cheap ecm (GM?).
 My real points are:
 That Hal-tek, Accel, and apparently Electromotive (see Espen's post) are
 selling stuff that is nearly useless for street tuning if their pw
 increment is 64 us!
 That we should do our best to set the 332 project up to give really fine pw
 increments--like 2us--there's certainly enough processore there to do that,
 and this is a damn good reason to do so!!
 That guys should be aware of the nature of the problem when deciding what
 unit to spend their money on, and why they might just maybe want to spend
 more!
 That it is guaranteed that the only reason that GM spent the money to get
 16 us pw increments (if that is really what they get) was idle emissions-if
 they did not HAVE to have done it, they would not have!
 
 I agree completely that mechanical injector (and fuel inertia) behavior
 becomes a big factor at very short pw's, but without small enough pw
 increment capability on the electronic side, we really do not have any kind
 of an accurate idea of exactly HOW short a pulse is possible before that
 factor takes over!
 
 Given the large pw increment that the DFI/Accel ecu is stuck with, I quit
 believing anything that they say about injector limitations!
 
 Did not know that Bosch was making a PWM FPR--tell me more.
 
 And tell Grumpy not to eat too much!!
 
 Regards, Greg
 
Hi All,
    It seems as though we are all arguing about injector control..comparing it
against mechanical and why it doesn't compare......if any of you have seen a
true tuned mechanical fuel injectioned system you would see different sizes of
nozzles per cylinder because of transport delays.....and it only covers up the
transients of acceleration of the engine....it does not even come close to
what happens in steady state conditions.........but this is drag racing.....in
an environment that has to do steady state and transients, a model of what
happens has to be built and learned upon......this is the gummints job to
understand or they cannot meet the up and coming legislation passed by people
that have no clue.......yeah I'd like to sit and bitch about it but it's a
true horror for all of us that like to improve our vehicles....if we can
introduce the technology from the aftermarket to the EPA,,,,,,,,,,,,,,we can
finally show them what true emissions is.........efficiency.....getting it all
from what we put in......I guarantee 99% of the gurus at the big three level
that make decisions have no idea what any of us are even talking about....they
want their numbers...set up by a bunch of people who don't know what it takes
to make the numbers happen...........what's the fix?????make some noise.....
-Carl Summers