Another injector question

[Bruce Plecan]

Right now, we are still debating MAP vs. MAF, maybe somebody could give me
some info to help in that area also. What are the benefits of each?

Gets right back to what exactly do you want to accomlipce?.
Steady state anything will work.
Transistions, MAP take an edge over MAF.
MAF has to have some *sense* time in the equation, where MAP is just kinda
looking at waves.
Again, just TPS and RPM, with enough feedback can be a simple functional
setup.
Is this for *day to day* driving, and need to be *emission* conscience?.  Or
just for HP.

 Also, what is a cheap source for MAF sensors, or could we just take a MAS
from a car and use it? How much does the shape & size of the intake ducting
affect the accuracy of a MAS?

Intake ducting for a MAF system can make or break it in a minute.  Reversion
is a very real problem.  Though min with a MAP.

Right now I am leaning towards (mostly) software control, via either a 68
series Motorola processor or through a PC/parallel port. Is there an easy &
accurate way to implement EFI through hardware only?

Using a bunch of comparators, you can do about anything.  Just gets to be
clumbersome.

What kind of feedback could we use other than O2 sensors, and exactly how do
O2s figure into your fuel calculations? I know my car's PCM just uses long
term fuel "trims" to compensate for variances in O2 readings. Are O2 numbers
ever used in immediate fuel calculations?

O2 numbers are meaningless.
It's about recovering heat energy, that is usually the concern.
you want HP, or Fuel Economy.
If going for HP, then you run for an optimime mixture, but you have to
experiment to find what that mixture is for your combination, and then shoot
for that.   you can't forecast what AFR (air fuel ratio) is optimime for
your engine.
Bruce

Steve Ruse

From: Bruce Plecan nacelp at bright.net
Subject: Re: Another injector question
>OK, we got folks working on SAE cars, kewl.
>Just what are you trying to do?.
>Build, a MAF EFI?.
>Might look first and see if you want to do software answers, or hardware.
>Complex, answers, or easy?.
>Tightly controlled feedback might make this real easy.
>
>What are you locked into?.
>Bruce

>From: Steve Ruse
>Subject: Re: Another injector question
>Hi, my name is Steve Ruse, and I am much in the same position as James. I
am
>working on a fuel injection system for a Formula SAE car at LeTourneau
>University. I have a lot to learn, and this list looks like a great place
to
>do that.
>The engine is a 600cc four cyl from a Honda CBR. I also own a '94 Z28 and
do
>custom EEPROM tuning on it, that is basically where I "cut my teeth" on
EFI.
>I am interested in the answer to James's last question, and I have also
have
>some questions of my own.
>First, what are some good sources for injectors? We have some for testing,
>but I don't think they are the ones that we will want to use in the end.
>What is the best way to test the flow rate of our injectors? Is there
>something better than just timing how long it takes them to move a given
>amount of fuel?
>Also, how can we account for the open/close delays of our injectors? Could
>that be accurately determined accurately by varying the duty cycle and
>seeing how the flow rate changes from when the injectors are at 100% duty
>cycle? Is there an easy way to keep our fuel pressure constant while
>performing this test? We were just going to try using an automotive fuel
>pressure regulator.
>Thanks!
>Steve Ruse

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