Another injector question

[Bruce Plecan]

> I'm far from an expert on the subject, but I can tell you the choices I
made
> regarding my SAE SuperMileage EFI system:
> > Right now, we are still debating MAP vs. MAF
> I went with MAF because I was under the impression a MAF system had a lot
more
> 'play' in it than a speed/density system. That is, a MAF system is more
> adaptable to changes in your EFI hardware than a MAP system, the software
> tables of which are generated for a certain throttle size, engine
displacement,
> etc. only.

??.
The play is what ever you design into it.
Super high mileage, would be done, with just a Aplha N system (effectively).

> Of course, a MAP system might be easier to implement and will probably
give you
> more reliable airflow data due, to the relatively long response time
inherent
> to MAFs.
> Our smallish (42mm dia.) low-flow (3-250 kg/hr) MAF sensors were donated
to us
> by Siemens Automobiltechnik in Germany. They like to sponsor teams like
ours
> and have their stickers gratuitously plastered all over our vehicles.

Corporate money talks LOL.

> > Right now I am leaning towards (mostly) software control, via either a
> > 68 series Motorola processor or through a PC/parallel port.
> I'm using a Motorola 68HC812A4 microcontroller on a board with 128 kb of
> additional memory (which I need for the lookup tables). It's got over 40
> digital I/O ports and 8 A/D channels, which are enough to handle all of
the
> sensors. There are inexpensive C compliers and freeware assemblers for
this
> processor, so programming it is relatively easy. I'm driving the injector
with
> a National Semiconductor LM1949 injector driver.
> Sensor-wise, I'm using a shaft-mounted optical encoder to measure rpm
(there
> are cheaper ways to do this, but we had an encoder sitting around) and
some
> hall-effect sensors to determine crankshaft angle. Engine temp. is being
> measured with a thermocouple, and I've also got a throttle-position sensor
to
> measure throttle angle and rate of change.

> I'm not worried about controlling the spark timing...I've got enough on my
> plate this year :) Next year's team can play with that.

What?.
That's the half the miracle.
Geeesh
Bruce

> james
>
> "God help us. We're in the hands of engineers."
> - from Jurassic Park

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