Another injector question

[Pat Ford]

 Gonna post schematics and such??

Previously, you (Steve Ruse) wrote:
{ James, thanks a lot for your help!
{ 
{ >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.
{ >
{ >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.
{ 
{ 
{ Heh heh, I need to make some calls......
{ 
{ >> 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.
{ 
{ 
{ Where can I find the C compilers etc. for the 812? I'm not our "software
{ guy", and all of my experience is with the 6811.
{ 
{ >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.
{ 
{ 
{ That is what I am thinking too. Why not use an optical encoder to measure
{ the crank angle? We are going  to do some testing with an optical wheel on
{ an electric motor before too long, just to see what we can do with it. What
{ optical encoder are you using? Also, what are you using the TPS for?
{ Enrichment at higher throttle positions? I was thinking of using a "3D"
{ table with enrichment as a function of MAP for that.
{ 
{ Thanks!
{ Steve Ruse
{ 
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--
Pat Ford                           email: pford at qnx.com
QNX Software Systems, Ltd.           WWW: http://www.qnx.com
(613) 591-0931      (voice)         mail: 175 Terence Matthews          
(613) 591-3579      (fax)                 Kanata, Ontario, Canada K2M 1W8

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